The Reference Frame

Kenneth Wilson, RIP

2013-06-19T08:59:00.001+02:00

Kenneth Wilson died from complications of lymphoma (a blood cancer) in Saco, Maine (where he and his wife were previously brought due to their love for kayaking) on Saturday, aged 77 years and 1 week. He received his Nobel Prize in 1982. His adviser was Murray Gell-Mann and students included Jackiw, Shenker, Peskin, and Ginsparg.

See also: WSJ, WaPo, Yahoo, NECN, Newsday, Google News, Physics World, Cornell, Press Herald, John Preskill, Clifford Johnson, a Shmoit

More importantly, he taught us about the concepts of effective field theories and the renormalization group that have explained why the renormalization works – and many other things. Many folks – a set that includes my PhD ex-adviser Tom Banks – classify Wilson's insights as the deepest advance of theoretical physics since the 1970s. Despite these experts' opinions, Wilson remained largely unknown to the public throughout his life.

The first talk of my life presented at a university different than my own that I ever gave was a 1998 talk at the Ohio State. Wilson has been there since 1988 and he could have arrived to the talk but (even though I was immensely interested in his presence) I have completely forgotten whether he actually has arrived. ;-)

I first met Wilson and talked to him during a lunch in the Society of Fellows overlapping with the 2005 Sidneyfest. He was smiling and satisfied and he was still thinking about physics although his most beloved newest theories seemed self-evidently silly – not only according to me but also according to some fellow Nobel prize winners – and he wasn't quite following the ongoing cutting-edge theoretical research. I also knew a younger Slovak lady (Martina M. Brisudova) who was his recent collaborator.

Kenneth Wilson is the father of the Wilson loop, the path-ordered exponential over a closed loop that counts the trace of the monodromy,\[

W_C := \mathrm{Tr}\,(\, \mathcal{P}\exp i \oint_C A_\mu dx^\mu \,)\,.

\] Such quantities are mundane for us today (and useful every day) but there used to be times when no one would eve dare to do such things with the gauge fields. Look at his impressive publication and citation record.

But more importantly, he became the main guy behind the Renormalization Group (RG). Physicists had learned the playful and clever tricks of renormalization but they didn't quite understand where it came from and some of them had doubts whether it should have been trusted at all.

Remotely related: On Thursday, 5 pm Prague Summer Time i.e. 11 am Boston Daylight Time, there will be a Google Hangout with top HEP phenomenologist John Ellis about SUSY on youtube.com/CERNTV. Use @CERN #askcern on Twitter to ask questions.

The Renormalization Group with its related machinery and terminology including effective field theories, relevant and irrelevant interactions, fixed points, and so on has eliminated all the doubts, unmasked the power that makes the renormalization procedures consistent and successful with a remarkable clarity, and gave us a modern understanding of what quantum field theory actually means (some people say that we are still waiting for analogous insights about the "true nature" of string theory). Wilson achieved these things in 1971-1974, building on the shoulders of Freeman Dyson's systematic theory of the old renormalization methodology from 1949 and Leo Kadanoff's 1966 ideas about the "block spin renormalization group".

What does this Wilsonian theory (some people could call it "Wilsonian philosophy" but this label doesn't reduce its robustness and importance in physics at all) say?

It says that quantum field theories (and similarly models in statistical physics that are mathematically analogous) should not be viewed as the final theories of everything but just as approximate theories that describe all objects and phenomena whose characteristic length scales are (much) longer than some $L$ or, equivalently, whose energies are (much) lower than $E$.

An important fact is that such a "restriction of the original theory", possibly a final theory, is possible at all. Why is it possible? Because we can explicitly construct it. Assuming that your "more complete" theory admits a formulation in terms of Feynman's path integral, we may define\[

\exp\left(-S_{\Lambda'}[\phi]\right)\ \stackrel{\mathrm{def}}{=}\ \int_{\Lambda' \leq p \leq \Lambda} \mathcal{D}\phi \exp\left[-S_\Lambda[\phi]\right].

\] On the right hand side, we are using a theory with the action $S_\Lambda$ and this theory is supposed to work for all energies/momenta up to $\Lambda$ which is very high. You may imagine this parameter to be infinite if you haven't thought about theories with a restricted domain of validity before.

All the calculable probability amplitudes are given by the Feynman path integral which is an infinite-dimensional integral over all field modes with various momenta. The key observation is that this integral may be reorganized in such a way that we first integrate it over the higher-energy modes, e.g. – in the formula above – modes with $\Lambda' \leq p \leq \Lambda$. In this way, we obtain a function that only depends on the low-energy field modes, $p\leq \Lambda'$, and the integral over these field modes can be done at the end.

A funny thing is that the function we integrate at the end only depends on the low-energy field modes – because the higher-energy field modes have been "integrated out" which means that they have been "integrated over" which excluded them "out of the list of variables upon which our favorite/remaining action on the left hand side $S_{\Lambda'}$ depends"). Still, this simplified function is totally sufficient to calculate arbitrary correlators etc. of the low-energy field modes (and scattering amplitudes for particles at low energies, among related things) as long as we "integrated out" the high-energy quanta properly and accurately.

The function that only depends on the low-energy quanta defines what we call the "effective field theory". Because its action doesn't depend on the high-energy quanta at all, this "effective field theory" will also generally become independent of any particles, fields, interactions, and laws of physics that only influence the very-short-distance or very-high-energy physical phenomena. We don't need to know the quarks to study atomic physics (or chemistry) and the Wilsonian "integrating things out" quantitatively realizes the same general idea in the technical framework of quantum field theories.

(You should bring your mind to the right mood by checking one of the interactive Flash animations showing the Universe at various length scales. Wilson effectively tells us to study the scales independently.)

So different theories valid for all distance scales, including the very short ones, may produce the same - or nearly the same – effective field theories for the low-energy modes. They may just imply the same spectrum of particles or fields at low energies and because their interactions are rather constrained (the space of effective field theories obeying certain extra conditions is rather small or exclusive), the interactions may agree, too.

Celebrations of the 1982 Nobel prize at Cornell. He looks very young among his colleagues – we're used to young people celebrating old men's Nobel prize – but he was already 46 on the picture above.

This was the first, more general part of the Wilsonian ideas: it's a good idea to separate physics to the physics at various scales. Short-distance physics affects long-distance physics that is derived from it; but the relationship doesn't hold in the opposite direction because short-distance physics is often left undetermined if we only know its long-distance manifestations.

The second part of Wilson's important contributions is a whole industry of methods that tell us how the effective field theories differ from the original ones in the case that the original ones are also quantum field theories, and we could even say that they are effective field theories as well but ones with a higher $\Lambda$ and how the space of possible effective field theories may be parameterized.

When I wrote the only big displayed equation above, I encouraged you to imagine that $\Lambda$, the highest scale at which the original theory was valid, was infinite while $\Lambda'$, the highest scale where the effective (derived) theory is applicable, is much smaller. However, the real technical power of the Renormalization Group shows up when the scales $\Lambda$ and $\Lambda'$ are actually very close to each other:\[

\Lambda' = \Lambda (1-\varepsilon)

\] Here, $\varepsilon$ is an infinitesimal positive number. In this case, the partial integration in the Feynman path integral is the integration over a thin shell of field modes $\phi(p)$ whose momenta (their magnitude) belong to a very narrow interval\[

\Lambda(1-\varepsilon) \leq p \leq \Lambda.

\] In other words, we are just trying to lower the scale $\Lambda$ by an infinitesimal amount. This changes the original quantum field theory to something else but because the change we have made is apparently "infinitesimal", the change of the quantum field theory should be infinitely small, too.

In fact, the derived effective field theory will be a theory of the very same kind as the original one but the values of the parameters – masses of particles and coupling constants – will be changed by an infinitesimal amount. We may always interpret the lowering of the value of $\Lambda$ as a "transformation" and these transformations may be composed associatively. There is also an identity transformation (keep $\Lambda$ and therefore the quantum field theory intact) so we may say that these transformations that lower the values of $\Lambda$ form a group.

Well, more precisely, we have said that the transition from a more complete theory with a higher $\Lambda$ to an effective field theory with a lower $\Lambda'$ is irreversible because this procedure is "forgetting" some particles and interactions that only mattered at high energies. Because of this irreversibility, the transformations lowering the values of $\Lambda$ don't admit any inverse transformations. An almost group without the condition that the inverse elements exist is called a semigroup but because physicists would think that the term Renormalization Semigroup is awkward, hard to pronounce, and dominated by mathematicians' nitpickiness, they use the term Renormalization Group. The (not quite) group elements are still the (associative) transformations reducing the value of the $\Lambda$, the maximum energy scale at which the effective theory works.

The procedure of lowering $\Lambda'$ has some impact on the parameters of the effective field theory. This effect may be calculated by Feynman diagrams (at least perturbatively) in which the internal lines are only integrated over a small interval or shell of allowed momenta and energies. When you do such a thing, you will find out that the couplings "run". They depend on $\Lambda$. (When you discuss the same kind of changes of all the parameters and perhaps even more qualitative changes of the whole theory that make the theory "run", the right verb is that we are "flowing the theory to the infrared".) The most important and perhaps the most typical functional dependence that appears in this running is the logarithmic running, something like (approximately, up to 1-loop diagrams)\[

\frac{1}{g^2(\Lambda)} - \frac{1}{g^2(\Lambda')} = B\cdot \ln\zav{ \frac{\Lambda}{\Lambda'} }

\] where the constant prefactor $B$ is related to the so-called $\beta$-function, the "rate" by which the coupling constant changes with $\Lambda$. Similar and perhaps more complicated "RG equations" are used to study how the parameters evolve from the high-energy scale to a low-energy scale. In particular, these "running coupling" calculations are totally essential to discuss the gauge coupling unification (convergence of the "fine-structure constants" of the three factors of the Standard Model gauge group to a common value at a high energy scale) in grand unified theories and for many similar applications. It's important to realize that as long as we identify the couplings with finite numbers that really correspond to some processes at a given energy, they are allowed to run.

If you want to use the RG methods to understand why the old renormalization methods – already used since the 1940s – work, it is a good idea to "map" the space of possible effective theories with a given spectrum and with some fixed value of $\Lambda$. If these theories form an $n$-dimensional space, it must be possible to deform each of them to get to a nearby effective field theory. These deformations may in turn be realized by adding a term (operator) to their Lagrangian.

For an effective field theory, you want to classify all possible deformations. They may be divided to relevant ones, marginal ones (the "unlikely", generically measure-zero border case), and irrelevant ones according to their influence on the very low-energy physics. In general, the relevant deformations are those whose effect is increasingly important as you move from high energies to low energies; the rule is reverted for the irrelevant ones and the effect remains equally strong at all scales for the marginal ones.

The most reductionist treatment of the perturbatively known quantum field theories such as QED or the Standard Model presents all of them as deformations of a "Gaussian fixed point". The adjective "Gaussian" means that the integrand of the path integral is Gaussian i.e. that the action is free (at most bilinear); there also exist non-Gaussian (interacting) fixed points but they're harder to be found. The deformations are all the interactions we are adding. The term "fixed point" refers to the theory's being unchanged under the renormalization group flows i.e. its being independent of $\Lambda$: fixed points are nothing else than scale-invariant theories – the most important lighthouses in the landscape of effective field theories according to the RG methods to map this landscape.

The deformations may be roughly identified with the extra terms in the Lagrangian that you might add. You will find out that the relevant ones are those whose coefficients have units of ${\rm mass}^n$, positive powers of mass, while the irrelevant ones have negative powers of mass. You will only find a finite number of relevant deformations but an infinite number of irrelevant ones – the latter are the "non-renormalizable interactions" (also essentially equivalent to what physicists call "higher-dimension operators"), such as \[

\delta S = L^4\cdot (F_{\mu\nu}F^{\mu\nu})^2

\] in quantum electrodynamics where $L$ is some parameter with the units of length.

Before Wilson, non-renormalizable interactions could have been interpreted as the ultimate blasphemies, extra terms that immediately throw us to a hell of inconsistencies (an infinite hell because there are infinitely many such terms we may add), something that we shouldn't even think about. Wilson's appraisal of their status is different. They're OK, you may actually add them, but they're "irrelevant" because their effect on the effective field theory below the scale $\Lambda'$ becomes negligible if this scale is much smaller than the original one, $\Lambda'\ll \Lambda$.

If you generate an irrelevant interaction in an effective field theory from the "integrating out" of some field modes, the typical magnitude of the parameter $L$ above will be of order $1/\Lambda$, i.e. linked to the very high-energy scale where the source of the interaction resides. This is why the effect of such a higher-dimension operator will be negligible around the low energy scale $\Lambda'$ because the coefficient\[

L^4 \sim \frac{1}{\Lambda^4} \ll \frac{1}{\Lambda^{\prime 4}}

\] is much smaller, by the factor of $(\Lambda'/\Lambda)^n$ with some positive exponent $n$, in this case $n=4$, than the typical size of the coefficient that you would have to expect (by dimensional analysis) if this interaction were as important as some relevant or marginal ones at the energy scale close to $\Lambda'$.

Once again, instead of being "immediate superstrong devils and killers of consistency", irrelevant interactions were reclassified as effectively harmless bugs. The higher the gap is between the low energy that you experimentally probe and the high energy scale where the irrelevant term originates, the more negligible they will be. Despite the small coefficient, they may still sometimes be important, especially if they generate rare processes that can't be caused by any relevant, marginal or otherwise "normally strong" interactions.

The marginal interactions are in between. For example, the fine-structure constant $\alpha\sim 1/137.036$ is dimensionless which means that the characteristic strength of the electromagnetic interactions is linked to a marginal deformation. Well, because this fine-structure logarithmically runs, it's actually not exactly marginal. These couplings have "anomalous dimensions" – the exponents have corrections proportional to $\alpha$ themselves. So the fine-structure constant only looks dimensionless classically; quantum mechanically, the corresponding coefficients have the units of a fractional power of the energy that is just close but not equal to the power derived classically.

(If you want exactly marginal deformations, you demand the quantum correction to the classical dimension – the anomalous dimension – to vanish exactly as well. This rarely occurs by chance and almost all important examples we know, at least for $d\gt 2$, are supersymmetric theories. Supersymmetry likes to guarantee similar cancellations. We also know important interacting supersymmetric theories that are nevertheless fixed points, i.e. exactly scale invariant. The $\NNN=4$, $d=4$ gauge theory is the most celebrated example while a non-Lagrangian six-dimensional $(2,0)$ theory is its much less well-known cousin.)

Ascania: Supersymmetry.

Such RG methods may also convince you that it doesn't matter which kind of a regularization – brute cutoffs, Pauli-Villars, dimensional regularization etc. – you use. The Wilsonian idea is that you focus on the space of effective theories i.e. those that are directly useful for the predictions of doable low-energy experiments. This space of theories – defined to be "almost directly relevant for the observations" – may be shown to exist and to have a certain dimensionality or allowed deformations and there may be many ways how this space is described or parameterized. These methods must ultimately differ by a redefinition of variables only. Whatever you can do with one regularization technique or renormalization scheme, must be translatable to another.

The "integrating out" is the key technique that allows us to translate the properties of the high-energy quantum field theory – something that may be rather directly linked to a more fundamental theory that doesn't have to be a local quantum field theory, especially to string theory – into the properties of the low-energy effective field theories that is almost immediately usable to describe the doable observations.

It's important that this translation – and the running of the couplings or flowing of the theories etc. – exists at all and it is not an identity transformation. It's important that the low-energy effective field theory is independent of many or most details of the high-energy physics. The previous sentence is pretty much equivalent to an observation from a different angle, namely that the behavior of quantum field theories (and even other high-energy starting points such as string theory) at low energies tends to be "universal". These possible low-energy behaviors may be discussed separately from the dynamics at high energies or short distances.

So what about the infinities that the old renormalization uses (and has to cancel) all the time? In the renormalization group philosophy, you may imagine that these are finite numbers that depend on a high energy scale $\Lambda$. These terms have to cancel by definition if our task is to study effective field theories i.e. descriptions that are independent of the physics above the high energy scale $\Lambda$. In particular, the effective field theory has to be independent of $\Lambda$ itself.

The cancellation of the divergences is no magic or blasphemy anymore. Wilson has shown that this cancellation pretty much tautologically follows from the very task we outlined for ourselves – the task is to study the observable low-energy phenomena which effectively means to study the effective field theory for a physical system (or the possible effective field theories for a class of systems). Because of this independence, one may also get rid of some contrived artifacts linked to a particular finite value of $\Lambda$ and study the limit $\Lambda\to\infty$ in which the cancelled terms are "strictly" infinite. It's just a natural limit that makes the unimportance of the physics at the high energy scale more self-evident.

The Wilsonian approach leads to a revision of many ideas about naturalness, the real problems with non-renormalizable theories, and more. Whether a theory is natural or not should be decided according to the values of the parameters at the high, fundamental energy scale; the values at low energies are their consequence. However, it may often be hard for a high-energy theory to "flow" to a realistic or semirealistic theory at low energies, e.g. to preserve any light particles that survive at all (if there are no particles lighter than $\Lambda'$, the "integrating out" may leave us with no degrees of freedom at all; the path integral becomes a boring constant because there are no variables left). The infinities themselves aren't a problem because you may always imagine that those numbers are finite; the real problem of the non-renormalizable interactions is that there are infinitely many of them whose coefficients have to be adjusted which makes the theory unpredictive for the phenomena near $\Lambda$.

All these insights were found independently of string theory and, effectively ;-), before string theory. And Ken Wilson wasn't even a string theorist at any point of his life (sorry, I don't count his strings on a lattice). Still, pretty much all the people who talk about nonsensical things such as "competing theories", "loop quantum gravity", and so on misunderstand most of the insights about the renormalization group – even the general comments above. Their beliefs about the character and right interpretation of renormalization techniques are stuck somewhere in the 1940s (especially because of the patently obsolete opinion that the real challenge when it comes to UV divergences is to get rid of divergent integrals). In this sense, these "anti-string-theorists" misunderstand not only the physics of the last 40 years but also the physics of the last 70 years. They're just hopeless.

The name of Ken Wilson in this very form has appeared in more than 20 older TRF blog entries. RIP.

Hooper: XENON100 may have seen DM candidates, too

2013-06-19T08:27:00.000+02:00

...if it's so, LUX will observe 1-6 DM particles a week...

Update 6/19: This astro-ph preprint says that LUX is already doing science and the results of a 60-day run will be out by the end of 2013, promising to brutally beat any competitor in their reach. Except for this short paragraph, this blog entry was posted on 6/10.

Dan Hooper of Fermilab released an interesting new salvo in the dark matter's war on existence,

Revisiting XENON100's Constraints (and Signals?) For Low-Mass Dark Matter.

Recall that the set of underground experiments that are trying to directly catch the particles of dark matter is divided to two violently competing subsets: one of them, the axis, vigorously claims that there can't be any signal in the other experiments. The leader of this axis is the XENON100 experiment whose claimed constraints are far more powerful than the upper bounds on the cross section published by the XENON100's allies.

© XENON100 Collaboration

On the other hand, the alliance of experiments that have already claimed to observe a rather strong signal of a dark matter particle, one whose mass seems to be 7-10 GeV (significantly lighter particles than those in the models that dominate in the phenomenological literature but in no way impossible), is apparently getting stronger every month. It seems that we're somewhere around 1943 in this particular war.

At least since 2010, the traditional leader of this alliance has been the CoGeNT experiment that also claimed to have observed the seasons, sort of confirming previous similar claims by DAMA, another paleomember of the coalition.

Juan Collar and N.E. Fields of the CoGeNT Collaboration have previously claimed that CDMS, formerly a member of the "dark matter is not seen" axis, was actually observing a dark matter signal as well, one that may have reached 5.7 standard deviations, high enough to claim a discovery.

This general claim that CDMS was going to join the "dark matter is seen" alliance was confirmed in April 2013 when CDMS announced that the CDMS was seeing three events that looked like a pretty clear 8.6 GeV or so dark matter particle. It means that we have had almost two months to get used to the notion that CDMS is among those who effectively claim that "something seems to be there", a coalition that also included CRESST-II since 2011, which leaves XENON100 alone as a proponent of the thesis that all the dark matter hints claimed by others have to be bogus. This situation makes it natural to think about air raids on Berlin.

Now, Dan Hooper claims that XENON100, the cornerstone of the dark-matter non-existence claims, is seeing two tantalizing hints of a light dark matter particle, too. The key image looks way too familiar from the recent CDMS charts, especially this one.

On the picture above, once again, you should notice two events that are significantly lower than the bulk of the background events although, for various technical reasons, the XENON100 papers have included them in the background as well. These events seem to be separated by a gap from the group of "clearly background-like events" and they seem to suggest the same mass of a dark-matter particle which would be unlikely if they were parts of some noise. And the mass is compatible with the 7-10 GeV interval indicated by the other experiments.

Based on common estimates, one could have expected up to 50 dark matter particles (which is much more than 2) to have been observed by XENON100. That's why the XENON100 folks are so self-confident in their claim that the dark matter particle with the parameters suggested by others can't exist. Hooper exploits conservative "what if" adjustments of various efficiencies and other boring and mundane parameters of the XENON100 experiment to claim that just 2 events of the sort could still be conceivable.

If this "yes, a particle is there" interpretation is right, then – according to Hooper – the emerging LUX experiment in South Dakota (which is also based on xenon and may be viewed as a superior sibling of XENON100) should see something between 3 and 24 events a month. If the answer is "Yes", then LUX could settle the argument about the existence of the particle rather quickly. Needless to say, dozens of dots near a curve which are sharply separated from the rest would be rather spectacular.

Superman is looking for a glitch in LUX.

The LUX website hasn't been updated for two months but it may be due to the webmaster's laziness or the experimental physicists' having something more exciting to work on these days. L.A. Times ran a fun story about the state of the experiment two months ago.

Incidentally, I must ask you: does any reader who is not Czech use the word "lux" for the vacuum cleaner? If she doesn't, where did we get this word from? Oh, I see, it's the brand called Lux, later Electrolux, founded around 1919. Before that, Lux was producing kerosene lamps, therefore the currently incomprehensible link of the vacuum cleaners to a word for light. ;-)

There was a videochat with the LUX (and Majorana Demonstrator) experimenters today.

Most species originate in the tropics

2013-06-18T17:05:00.001+02:00

Yesterday was the first really good day of 2013 to swim in a pond – two months later than in 2012 – and today is the first supertropical day of the otherwise cloudy year 2013 with temperatures reaching 35 °C in Pilsen where the warmth has its headquarters. Prague was colder but 33.5 °C was still enough (by 0.3 °C) to beat the record for this day which didn't occur in 2012 but in... 1934. ;-) A tropical topic may therefore be appropriate.

Because Slovak geologist Mr Adam Tomášových is among the 8 authors of the paper, the science section of the Slovak daily Sme.sk reviewed the article

Out of the tropics, but how? Fossils, bridge species, and thermal ranges in the dynamics of the marine latitudinal diversity gradient

written by David Jablonski et al. and published in PNAS. See also futurity.org.

They looked at three slices of Cenozoic (from 66 million AD through now) and decided that most marine genera originated in the tropics. You may view the paper as a followup to the "out of the tropics" mechanism coined by Jablonski and others in 2006.

They were also interested in the way how these tropics-born species migrate into the moderate zone. A heat wave is probably necessary for such a migration while intraspecies adaptation and the diversification rate of a species is helpful to allow a new species to migrate out of the tropics.

I think that most of us will find these statements somewhat uncontroversial and plausible. Tropics is where the concentration of life is maximized. Moreover, the Sun and heat probably tends to increase the mutation rates over there which is why the percentage of the species originated in the tropics is likely to be even greater, probably much greater, than the percentage of the individual organisms that actually live there today.

Tropics are the place with the highest biodiversity and it's no coincidence. Their research shows that this has been the case at many distant moments in the past, too.

An interesting concept promoted by the paper are the bridge species. A seemingly sensible yet naive assumption known as "niche conservatism" is that species tend to live in similar habitats as their relatives. However, according to this paper, many jumps (in some analogy, jumps over the river) have occurred and they were extremely important. For these jumps to be possible, one needed one of the rare special species, the bridge species, that allowed life to spread to less hospitable (essentially cooler) places. Just to be sure, "niche conservatism" will be obeyed in most cases if you look at random animals and their ancestors. However, this "niche conservatism" assumption prevents you from explaining the origin of the bulk of biodiversity on Earth.

There are only one or two bridge species per evolutionary lineage – a small percentage of all species – and all these bridge species seem to have originated in the tropics themselves. The paper also finds something you may view as counterintuitive: the most widespread species are not those that tolerate the largest temperature swings. In fact, those that tolerate a narrow interval are (at least in the case of bivalves) the most widespread ones. But it's not so illogical as you might think because the narrow tolerated interval may be adjusted by evolution, too. Moreover, the tropics represent a significant part of the Earth and the temperature over there is rather constant so too much tolerance isn't needed.

The global warming alarmist censors must have misunderstood the paper completely because they couldn't stop the publication of this paper despite the fact that according to these loons, liars, and demagogues, a warmer weather is hurting (and is probably going to destroy) life on Earth. ;-)

More seriously, if the tropics offer the best temperature for life on Earth, we may calculate how much the temperature should rise (uniformly over the globe: an assumption) for the life's well-being to be optimized over the globe. Clearly, it would be better for the optimum temperature to be found in the moderate zone – which has a greater area and which is currently about 20 °C cooler than the optimum tropics. It follows that the optimum global temperature rise for life is at least 20 °C. I say "at least" because there are no available data that would directly or indirectly imply that the optimum temperature for life isn't even higher than the current temperature of the tropics. Compare this scientific fact – that a 20 °C temperature rise would be beneficial for life – with the insane fearmongering about a 2 °C warming (from which only 0.7 °C or so was realized in the last 100 years).

All proofs in natural and social sciences ultimately depend on probabilities

2013-06-17T09:20:00.000+02:00

Mel B. has sent me a link pointing to a rather incredible attack by an economics professor on the statistical methods in science that was published in the Financial Post:

Junk Science Week: Unsignificant statistics

Stephen Ziliak doesn't want to believe the existence of the Higgs boson – or any other "proof" in science that is based on the notion of statistical significance. In fact, we learn – in big fonts – that

Statistical significance is junk science, and its big piles of nonsense are spoiling the research of more than particle physicists.

Wow. It's remarkable because with this deep misunderstanding of the very key part of any rational thinking, this Gentleman can't possibly understand anything about the proper verification of theories in economics, his field, either. I would argue that because of this lethal flaw in the author's approach to rational reasoning, it is guaranteed at 5 sigma that your humble correspondent and many other physicists and scientists simply have to be better economists than Mr Ziliak, too. He just can't have a clue about the scientific approach to anything.

Statistical significance is absolutely paramount in the verification of hypotheses in all natural sciences as well as all social sciences that more or less successfully try to emulate the scientific character and success of the natural sciences.

Only in mathematics, we may construct rigorous proofs that don't need to mention any probabilities because in principle, the probability that a mathematical proof is right may be verified to be 100 percent. There's no noise and no uncertainty in a rigorous mathematical proof.

However, this "optimistic observation" has two major limitations. One of them is that mathematics doesn't directly apply to the real world. As long as mathematical concepts, theorems, and their proofs are considered rigorous, they can't be reliably and accurately identified with anything in the real world. So they tell us nothing about Nature, humans, or the society. Claims about Nature, humans, or the society simply don't belong to mathematics. They can't be absolutely certain. They can't be rigorous in the truly mathematical sense.

The second limitation is that people aren't infallible so for various reasons, even a mathematical proof has a nonzero probability to be wrong. Even if a proof is carefully verified etc., there's always a nonzero probability that the brain or the computer performed an invalid operation that led to the confirmation of a proof that is actually erroneous. The embedding of mathematicians' brains in Nature guarantees that these brains can't quite share the perfectly clean, infallible features of the idealized world of mathematics.

In natural sciences, the verification and falsification of hypotheses – and falsification in particular is the basic methodology that makes observations relevant (and observations have to be relevant for anything that we call science) – always involves measurements that have some uncertainty, a nonzero error margin, or a risk that a phenomenon is caused by different causes than those we want to search for. This is a fact: the world is simply messy and complicated. It is partly unpredictable. It is not a clean and transparent celestial sphere with perfectly spherical angels.

We may develop mathematical models and theories that are meant to match the observations and they may be free of any remarks about error margins, backgrounds, or false positives. But as soon as we do anything that remotely involves the theories' verification – and in sciences, the verification ultimately boils down to empirical verification – we simply have to acknowledge that each measured quantity has a nonzero error margin because it can't be measured quite accurately. We must acknowledge that an event that looks like a proof of some new phenomenon predicted by a theory was actually caused by a more mundane – while perhaps more rare and less likely – effect that combines the known mechanisms.

We must not only acknowledge it but we must also quantify all these things. We must know whether the error margin of a measurement is small enough so that the measurement is useful and trustworthy concerning the validity of a proposition. In the same way, we must know whether it's conceivable that the event apparently proving a new effect is actually caused by a combination of an older, less extraordinary theory combined with some reasonable amount of good luck.

For all these things, we have to quantify the probabilities.

The Higgs boson was officially discovered once the probability that the pairs of photons or Z-bosons with the right energies that really look like coming from a new, 125-126 GeV heavy particle, were so numerous that such a spike in the number of these events was very unlikely to appear without a new particle. By "very unlikely", particle physicists mean the chance "1 in 3 million", also known as "5 sigma", that the excess was a fluke that appeared in a world without a new particle.

Some disciplines of science try to be as hard and reliable as particle physics so they adopted the same 5-sigma (1 in 3 million) standard for discovery; most other disciplines, especially soft sciences such as medical research, climate science, psychology, and others, are often satisfied with 3-sigma (1 in 300) or even 2-sigma (1 in 20) evidence.

The number of sigmas determine the deviations from the null hypothesis. A null hypothesis is some simple enough explanation "without new players" that admits some controllable noise according to some calculable statistical treatment. If it predicts that a quantity $X$ has the value $X_0\pm \Delta X$ where the distribution is normal (and it is very often almost exactly normal, and even if it is not normal, we usually know what it looks like and we can calculate the probabilities for other distributions as well), i.e. $C\times \exp[-(X-X_0)^2/2\Delta X^2]$ where $C$ is chosen so that the "total probability of any possibility" equals one, then it is possible to calculate that the probability that $X$ doesn't belong to the interval $(X_0-5\Delta,X_0+5\Delta X)$ is approximately 1 over 3 million which is so tiny that physicists are willing to take the risk and announce the discovery.

The total significance of the deviation from the Higgs-less null hypothesis is now around 10 sigma or so which makes us really sure that the Higgs-like excess isn't just a fluke. The probability that the excess is just a fluke – a collection of coincidences – is much smaller than 1 in a quadrillion. These numbers are so large because $\exp(-x^2)$ decreases really quickly with $x$, more quickly than exponentially, in fact.

When the discrepancy between a theory and the observation becomes this high, we may eliminate the null hypothesis (in this case, a crippled Standard Model where the Higgs is amputated). This is the process of falsification and it's the key empirically rooted procedure by which any science makes some progress in its ability to distinguish viable hypotheses from the disproved ones. To disprove a (null) hypothesis is this straightforward. On the other hand, we can never "quite prove" any detailed theory because there's always a possibility (and, with an exception of the truly final theory, pretty much certainty) that more extensive and accurate experiments in the future will falsify the latest best theory, too. Equivalently, the absence of a statistically significant (e.g. 2-sigma or 5-sigma) deviation in the latest data doesn't mean that the null hypothesis is right and will be right forever. It just means that the deviations as displayed in the performed experiments are smaller than a certain bound which implies that the current theory is "practically" correct. In the future, a discrepancy may be found in more accurate, refined, or extensive experiments that may see tinier or subtler effects than what we can see today.

One simply can't ever deduce any conclusions from the empirical data with absolute certainty. It's always important to acknowledge that an uncertainty is there. And because such an uncertainty may compromise the conclusions, it's always important (sometimes more important, sometimes less important, but never quite forgettable) to quantify the uncertainty, i.e. to know how large it is. The most invariant way of quantification is ultimately one in terms of the probability that a conclusion is invalid because an anomalous observation or a "smoking gun" wasn't really caused by the new effect whose existence we wanted to prove but rather by some good luck (or bad luck) – an amount of luck that can't be quite small (because, as we assume, the observation doesn't look like the most typical prediction of the null hypothesis) but it can't be too large (because it may still realistically happen).

All this methodology is absolutely essential for any controlled, reliable enough empirical tests of any theory or any hypothesis in any natural or social science. We may only discuss how high our certainty should be for us to authoritatively claim that our experiments or observations have established something (the requirements may depend on the context a little bit). 5-sigma is the usual standard of the hardest sciences (led by particle physics) for the discovery. It wouldn't hurt if other sciences adopted the same standards. When a dataset produces 2-sigma excesses, which still has a substantial, "1 in 20" risk of a false positive, you only need a 2.5 squared i.e. 6.25 times larger dataset to achieve a 5-sigma excess where the risk of a false positive is just "1 in 3 million". I am confident that science would be much clearer if surveys with mere 2-sigma excesses were summarized as inconclusive ones. Lots of bad and questionable results in soft sciences are caused by their low standards on how many sigmas we need. These bad apples have far-reaching consequences because many other papers try to build on these bad apples, and so on.

But if someone wants to abandon the null hypothesis testing and the notion of statistical significance in general, he is surely throwing out the baby with the bath water. He can't possibly understand how proper science is done; he couldn't have possibly done any empirical research that could be uncontroversially considered scientific. In fact, as we have often emphasized on this blog, all predictions of fundamental theories of physics ultimately have to be probabilistic (even if you remove all the technological limitations of measurement devices etc.) because quantum mechanical postulates have to be universally valid in the whole Universe and every small or large corner of it.

Mr Ziliak tries to excuse his silly remarks by some confusing assertions about the nature of particle physicists' claims about the Higgs boson. The 5-sigma excess doesn't prove the Higgs boson, he says: it could be a Prometheus particle, too. But if he's serious, he misunderstands what terminology means in physics – and science. You are free to use the name "Prometheus" for the Higgs boson; after all, many of us use many other names at various points, such as the God particle or the BEH boson (only Peter Higgs really noticed the extra bosonic excitation named after him). But while the people are free to choose their language and terminology, physics isn't about terminology. Physics is about the observable phenomena. So even if the source of the bump were Prometheus according to your terminology and your belief system, it's still empirically demonstrated that this Prometheus behaves as the Higgs boson. If it looks like a God particle, walks like a God particle, and barks like a Dog particle, then it is a God particle (if you change one Dog to God). It doesn't matter whether someone says it's a Prometheus, too.

At the beginning, the new particle was given uncertain names and it was Higgs-like because there was clearly a new particle-like effect and its properties were compatible with the properties of a Higgs boson. Later, as we were more certain and knew more accurate values of the properties, we became able to falsify the theory that the bump is caused by something that differs too much from the Standard Model Higgs boson. At this point, we have everything we need to call it the Standard Model Higgs boson. By this claim, we don't mean that the Standard Model will forever be the right and complete theory for all observations. It almost certainly won't be. But the observed properties of the Higgs boson falsify so many competing hypotheses and are so nontrivially close to the predictions of the Standard Model Higgs boson that there's no reason not to use this name for the object. So the new particle may be a Prometheus but according to the physical definition of "being a Higgs boson", it is clearly a Higgs boson, too. Physics determines whether something is a Higgs boson by its decays, rates of production, mass, and other interactions, and if those things agree with the Higgs boson's property, then the particle – whether it is God or Prometheus or anyone else – simply is a Higgs boson and attempts to claim otherwise are just artifacts of a distorted terminology, mistakes, and demagogy.

When I talked about the certainty that the LHC has observed a new particle; a new Higgs-like particle; or a Standard-Model-like Higgs boson (these phrases are increasingly accurate and increasingly strong), I only took the (almost) purely experimental data into account. Aside from these nearly direct observations, we have nearly rock-solid theoretical arguments – that I won't offer to Mr Ziliak because he isn't smart enough to understand them as even the very rudimentary concept of statistical significance is already too hard and abstract for him – that there has to be a Higgs boson with the mass or other properties that can't differ from the observed ones by more than a relatively small amount. The Standard Model (or any theory with particles including the W- and Z-bosons and others we have known for 30 years) would simply produce inconsistent predictions (such as probabilities of some high-energy collisions exceeding 100 percent) if the Higgs boson weren't there. While an experimenter may view all these arguments as biases and he should perhaps only build on what he has seen with his own eyes, other physicists are more than free (in fact, nearly obliged) to use all the available evidence to decide about the existence of the Higgs boson (as well as any other scientific question). With this additional, mathematically sophisticated evidence added to the mix, there's really no doubt that Nature contains a Standard-Model-like Higgs boson. There's no sensible doubt about millions of other scientific claims, either. But the probability that these insights are right is never quite 100 percent although it has gotten insanely close to 100 percent in very many cases.

Mike Duff vs an anti-string layman

2013-06-16T12:35:00.000+02:00

Giotis has pointed out an argument published in the Guardian:

A theory of everything ... has physics gone too far?

Mike Duff of the Imperial College tries to teach something about the foundations of physics to a self-confident layman called Jim Baggott (yes, I had to press backspace when I instinctively started his surname with an F) who is obsessed with irrational critiques of the state-of-the-art physics and who has even written a book based on all these fallacies (see the link below).

The title of the article asserting that "physics that has gone too far" is a rather accurate picture of the basic nature of the string theory's critics – their proximity to the Inquisition that wants to dictate which boundaries science isn't allowed to surpass. Science is "allowed" to surpass any boundaries. Any question where a sufficient body of evidence and relationships between the known and hypothesized facts may be developed is likely to become a fruitful subdiscipline of science. String theory undoubtedly belongs to this list.

Baggott effectively claims that string theory was completed 40 years ago and by this time, everything should have been settled. Duff explains to him that string theory was actually born 40 (well, 45 if one includes the years in which it wasn't called string theory but it was already the same subject) years ago and the insights have been accumulating during the subsequent years and they're still being accumulated which is really why the ongoing research makes sense.

Duff can't resist to point out an important example of such a development that occurred much less than 40 years ago – the discovery of 11D M-theory and the role of membranes in M-theory. It was important, indeed, and Duff himself has made important contributions to this advance years before M-theory got its name. My estimate is that a dozen of advances are as important as the discovery of M-theory and its connections to string theory.

Baggott, like many laymen, believes that science is supposed to talk about things that have already been measured only. Duff corrects him and explains that an important, nearly defining part of science is about predictions and analyses of things that have not been observed, even things that are not gonna be observed soon according to any plan.

So there's some debate in the British daily on whether or not the atomic theory or Einstein's papers about entanglement were physics or metaphysics or speculation. It's a matter of terminology but it seems totally obvious to me that this activity is an important part of what physicists do, have always been doing, and have to do for the progress in physics to be balanced. Einstein was clearly doing physics when he was writing EPR-style papers. We cite him (and them) for those insights and questions. Some of the physics was wrong, some of it may be classified as speculations about alternative theories that can't exist, but in some of it he just followed the proper laws of quantum mechanics to derive certain interesting phenomena (whose validity and whose character in Nature Einstein often misinterpreted and mispredicted).

It was right or wrong but it was surely physics and we cite Einstein for these things, too. What string theorists are doing is much more robust and rooted in the empirical data than Einstein's work about entanglement. String theorists are arguably much more right about string theory and questions it addresses than Albert Einstein when he talked about entanglement. Duff also has to point out that string theory is as rooted in the known empirical facts as the Standard Model.

There are other topics – I endorse every word by Duff – and at the end, Duff tries to clarify a common laymen's (and Baggott's) fallacy. They love to confuse implications derived from a theory and theory's assumptions. In particular, Duff explains that supersymmetry, extra dimensions, the existence of string or membranes (at energies smaller than or equal to the Planck scale), and various other types of physics aren't assumptions of the theory we have but its predictions, something we have derived from a more coherent and fundamental starting point.

Even if you're confused about these matters, you should be able to understand that it's important to distinguish assumptions from derived predictions – the difference is as important as the difference between positive and negative numbers, between credit and debit. They're really standing on the opposite sides of a seesaw so if you're confused which side, it is likely to dramatically invalidate your conclusions. ;-)

String theory allows us to derive known aspects of physics such as general relativity, gauge theories, chiral fermionic matter, but also new aspects such as supersymmetry, grand unification, exotic heavy states – and more theoretical insights such as the nontrivial mechanisms that preserve the information when black holes evaporate, and so on, and so on – from a more unified and fundamental starting point. Only the starting point which is extremely robust or rigid is "adjusted"; all the other claims are implications of them.

Update: There was another exchange in the Guardian on Sunday between John Butterworth and Mike Duff (e.g. first comment), among others. Butterworth isn't a layman. He is an experimenter but it seems he completely misunderstands the work of theoretical physicists. Among experimenters, he isn't the only one. I won't spend more time with Butterworth's musings because they're just a softly formulated form of the very same delusions that the deeply misguided anti-theoretical-physics mob writes everywhere. I sort of believe in the renaissance man so even if someone like Butterworth is an OK experimenter, his Fachidiocy and a complete misunderstanding of a closely adjacent discipline to his – theoretical physics – is just stunning. If he could at least keep his mouth shut instead of boasting his delusions.

Valentina Tereshkova: 50 years ago

2013-06-16T07:52:00.000+02:00

Exactly 50 years ago, on June 16th, 1963, the first woman went to outer space.

The story of Valentina Tereshkova is also a story of the remarkable similarity between the propaganda tools of the Soviet Union and those employed by feminism and other pathological ideologies of the contemporary Western society.

Gagarin, Popovich, Tereshkova, Khruschchev...

For some time, the Soviet Union appeared to be ahead of the U.S. in the space race. Sending a female cosmonaut to the orbit was a natural next argument designed to support the (preposterous) claims that communism was technologically superior to capitalism.

To make the message really strong and ideologically convenient, many details of the selection had to be social-engineered and many facts about the spaceflight had to be censored for decades.

Not everyone was eligible to participate in that Vostok 6 spaceflight. She had to be female. But any female wouldn't be good enough. It had to be a female from the "right" class, the working class. (I suppose that the PC folks in the U.S. would prefer a female "minority" these days – structurally speaking, those biases are the same.) So they were searching through factory workers and textile factory assembly worker Tereshkova who was an amateur parachutist looked great, especially because her father was a war hero of the Soviet Union, a tank leader sergeant who died in the Finnish Winter War. She was extraordinarily more-than-loyal to the party ideals and became a member of the communist party later, too.

I don't have to explain you how dramatically you weaken the pool of candidates if your cosmonaut has to satisfy not only the sexuological criteria but also the political ones. But the creation of the right "role models" was primary; meritocratic considerations were secondary.

The spaceflight itself was a 48-orbits-long sequence of mistakes, glitches, whining, violations of the plans, and a permanent existential threat.

Only in the late 1980s, people started to learn that she was crying throughout the spaceflight and begging to return to the blue planet as soon as possible. This article is among those that summarize all the incompetency and physical inadequacy that determined the character of Tereshkova's spaceflight. A much longer article about the fiasco launched by intrigues and plots was automatically translated from Czech (1st part; 2nd part about her near-cutting of her head etc.; 3rd part about bruises and censorship).

In the beginning of the first day, things looked sort of OK. She was communicating with Vostok 5 that already out there and even sang songs to Valery Bykovsky over there. It was also the first day of glitches. The spaceship was erroneously programmed not for landing but for taking the ship into a higher orbit. The error was fixed and everyone was obliged to remain silent about it. When I say silent, I mean for 44 years: only in 2007, Tereshkova admitted that the speculations were true and the potentially lethal programming glitch did occur.

In the official report, she complained that she had to vomit. Her helmet was too heavy on her shoulders and scratched her head while the spacesuit hurt her leg. She couldn't feel comfortable enough in the weightless state. The limited size of the spaceship was frightening, too. Needless to say, this official report of hers was censored as well.

More seriously, she had trouble to guide the spaceship. For example, her invalid maneuvers interrupted the communications just before descent began. General Nikolai Kamanin, the boss of the spaceflight sector at that time, revealed those things many years later and admitted that the selection of Tereshkova was a mistake. In the 1960s, he was behaving differently, however. For political reasons, he continued to sing odes to Tereshkova and criticized two arguably more prepared candidates, physically and by their skills, namely Valentina Ponomaryova (who had a husband, kids, love for cigarettes, and self-confidence, imagine that!) and Irina Solovyeva (who was not sufficiently socially active!).

Tereshkova couldn't follow the eating schedule – ate only 1/3 of what she was supposed to eat (she partly decided in this way because she was shocked that she should use the spacesuit to remove the feces, as prescribed) which is why she fainted at the end – and took her shoes off, for the sake of convenience, like a diva and in a conflict with the regulations.

After Tereshkova catapulted out of her capsule and parachuted to Southern Siberia – as expected – her location wasn't known for two hours because she landed about 6 miles from the right place. While landing, she bruised her nose by smashing it against the visor. The bruise was covered up by make up during ceremonies. We often tend to agree with Steven Weinberg that manned flights don't bring any real added value – except for a highly increased price. Sometimes we have doubts about that but I have no doubts that similar womanned flights bring no added values except for lots of extra hassle and unnecessary problems.

Tereshkova remains the only female solo astronaut in the history and the number of female astronauts is still limited. Someone tried to design an all-female mission but certain experienced professionals who are sometimes called "male chauvinists" have vetoed such plans. While Tereshkova's spaceflight was painted – and mostly is still painted – as a great success in the mass culture, the space program professionals evaluated the "success" so that they didn't send any new woman to space for 19 long years after her. When the world's second woman, Svetlana Savitskaya went to space in 1982, your humble correspondent was already watching, and so were most of you. ;-) Savitskaya had actually been not only a parachuter but also a trained (and employed) aircraft construction engineer, a world champion in some propeller aircraft disciplines etc., a really competent cosmonaut (she had no trouble with spacewalk, the first woman to do it) and at least her male colleagues' real peer (although another communist). But back to 1963.

Khrushchev arguably knew about all the fiascos surrounding Tereshkova's flight but he had the chutzpah to boast about the flight that "demonstrated the equality of men and women in our country [USSR]". Imagine how preposterous such a claim is given the fact that she did almost nothing well. The event was an achievement of several top men in the space program who faced no barriers when they put at risk the life of a nearly unprepared woman in the very same way in which they previously risked the life of Laika the Dog – to boost their own pride.

Sergei Koroliov, a big shot in the Soviet space program, wasn't a supporter of female astronauts as a concept but he at least insisted that the serious candidates would have to give up plans to have children etc. Most of the candidates at the beginning failed in tests of withstanding 80 Celsius degrees and up to 10 g of acceleration. The shortlist was composed of 18 women that were further reduced to 5 at some point.

Totalitarian ideologies and ideologies attempting to brainwash whole nations simply depend on certain "nice assumptions" and the claim that women are statistically equally good in similarly extremely physical and technical situations has always been one of the most favorite "nice assumptions" of this sort. They're really "not so nice lies", not "nice assumptions", but they're popular exactly because many other people know that they're not true. This fact has the effect of unifying those who are willing – or who were forced – to accept and defend the non-truth.

Tereshkova was a textbook example of a product of a spoiled ideology and a politically deformed job contest. But there were many personal deformations, too. Tereshkova was running around the offices, spreading insulting gossip about her competitors. Despite the de facto complete failure of her flight (except that she managed to return at all), she later became very prideful, convinced that she can do everything. So she was constantly deciding who should be the next one to get the orders of the Soviet Union etc. She was repeatedly drunk and fought against cops etc. but she was always freed and cleaned.

It may be nice to have role models but as soon as it becomes clear that the production of role models has become the primary obsession, and probably much earlier than that, sensible people should realize that the truth, meritocracy, and actual goals of the industries and programs are much more important than the good feelings created by the virtual reality. Propaganda sucks and so do the spoiled brats created along with it.

And that's the memo.

There is no classical world

2013-06-15T09:00:00.000+02:00

...even Sean Carroll may say true things about the foundations of physics...

How is it possible? Well, quantum mechanics implies that if a process isn't prohibited by some absolute laws such as symmetries and conservation laws, it may happen even though the probability may be very tiny (like in quantum tunneling; or in Carroll's authorship of valid sentences about quantum or statistical physics).

Sean Carroll decided to promote an animated cartoon film on quantum mechanics, previously embedded in John Preskill's blog – it's nicely done but you may ultimately think that it's missing a Wow factor – and he said some correct things.

The most important one appears in the title: there is no classical world. Carroll correctly states a self-evident fact – that is nevertheless underappreciated by many – that classical physics is just an approximation for certain phenomena. It becomes increasingly more relevant or accurate when objects and processes become more classical (which usually means bigger) but it never becomes exactly true.

Let me admit that whenever Carroll writes such a thing, one that contradicts Carroll's hardwired emotions and sentiments, I can't get rid of the impression that he was just persuaded by John Preskill to do so. It seems somewhat implausible to me that after all these passionate posts he wrote about the need for realism and the extensive space he has given to "philosophers" i.e. crackpots who try to interpret quantum mechanics as an illusion ultimately boiling down to a classical model, he would voluntarily write what he wrote now. But good that he did it, anyway.

It was sort of courageous because a vast majority of the readers of similar blogs – probably including this one – is controlled by uncontrollable anti-quantum instincts. Carroll's comment section shows it's the case. Let's look at it.

In the first comment, Ted J. Vlamis writes

I notice your careful choice of words that “there is no classical world”, as opposed to “the entire universe is quantum mechanical”. Any thoughts on reconciling the contradictions between Quantum Mechanics and Relativity.

Carroll said that "there is no classical world" but according to a somewhat intimidating body of evidence, the proposition "the entire universe is quantum mechanical" is a valid and important proposition, too.

Moreover, there is no contradiction between quantum mechanics and relativity. Their union is even more constraining than each of these two foundations of modern physics separately but the constraints admit solutions, anyway, and they're beautifully consistent. In fact, the full-fledged quantum (probabilistic, non-realist, and so on) character of the laws of physics is the only way how to reconcile the empirically verified violations of Bell-like inequalities with the principles of relativity. The principles of (special) relativity, which were extracted from many experimental situations, along with several additional very specific experimental facts (about entanglement etc.), may be used to directly prove some postulates of quantum mechanics.

In the second comment, Carroll replies to Vlamis as follows:

There are no contradictions between quantum mechanics and relativity; quantum field theory reconciles them beautifully. We’re still looking for a complete quantum theory of gravity (whose classical theory is general relativity), but that’s another issue.

Right, there are no contradictions between (special) relativity and quantum mechanics and quantum field theories (and string theory) are explicit proofs of that.

Carroll doesn't directly say whether quantum mechanics is compatible with general relativity although he mentions it. So this question deserves a few sentences. General relativity can't be used as a starting point to construct a quantum theory of gravity following any straightforward standardized process of "quantization". So general relativity may be said to be incompatible with the procedures of "quantization" that work for other theories.

However, in contrast with claims in the popular literature, it's really misleading to say that the principles of a relativistic description of gravity (which boil down to general relativity in the classical limit) are incompatible with quantum mechanics. They're surely not incompatible. After all, we know that the string theory vacua flawlessly reconcile the principles from both pillars.

The correct statement is that classical general relativity and general quantum mechanics don't immediately tell us what phenomena occur in extreme conditions, such as the Planckian distance scales, where both quantum mechanics and strong gravitational fields become relevant. When it comes to the principles themselves, those of quantum mechanics and those of general relativity aren't incompatible. Their union is just subtle enough so that we can't immediately derive their implications for the world in which the quantum phenomena and strong-gravity GR phenomena overlap. But that's it. The overlapping region ultimately is described by a consistent theory; and the regimes controlled by GR only or QM only can even be described by a theory that was understood before people started to reconcile GR and QM.

The third comment by Joe focuses on the experiment from the animated film that I decided to embed above this very sentence:

The video shows how there is only a red shift of the reflected laser light when the mirror is in its ground state, because no energy can be extracted from zero-point energy of the ground state. At first I thought this was amazing but then I wondered how this differed from the classical prediction. In a classical picture, the mirror in its ground state would be completely motionless. The laser still cannot be blue shifted because the mirror is motionless but red shift is possible because the laser can impart energy to the mirror. Can someone explain how this experiment demonstrates a quantum phenomenon? (BTW, I’m not a quantum denier, I just can’t wrap my head around the experimental results.)

The movie starts with a few general comments on particles and waves and the uncertainty principle. Then it discusses the experiment with a small but not atomic-scale mirror that contains billions of atoms (30 microns times 30 microns or something like that). Laser light is sent to the mirror and reflected. Using helium, the mirror is cooled down almost to the absolute zero and they're ready to measure the blue shift or the red shift.

Classically, the mirror sits at $x=0$ with $p=0$. The red shift would have to be zero. Quantum mechanically, this is not allowed as it would violate the uncertainty principle. In quantum mechanics, one may derive that this ground state implies $\Delta x$ of order one femtometer. The reflected light can't carry a higher frequency/energy because it would have to steal some energy from the mirror but there's no lower-energy state than the ground state. So only red shift is possible.

In the real-world experiment, one doesn't have $T=0$ exactly so the blue shift won't be absent completely. But quantum mechanics still predicts a different behavior than classical physics. Classical physics predicts that when the mirror is slightly moving before the collision, and at $T\neq 0$, it is indeed moving, blue and red shift are equally likely because the mirror is equally likely to move against the laser beam as it is to move away from the laser beam.

I suspect that unusually enough, Joe misidentified the reason for the red shift or blue shift in classical physics. The right (Compton-like) description in classical physics is in terms of a photon-mirror collision that simply gives the reflected photon an extra positive or negative momentum depending on the previous motion of the mirror. You won't be able to say much if you only look at the energy of the mirror because the energy conservation law isn't enough to determine the momenta of the mirror and the photon after the collision. However, if you add the momentum conservation law, you may watch the whole collision e.g. from the center-of-mass inertial system and in this frame, the final photon's energy is clearly the same as the initial one. The blue shift or red shift in the lab frame is then derived from the Doppler shift – from the relative motion of the lab frame with respect to the center-of-mass frame. This Doppler shift depends on the initial velocity of the mirror and both signs are clearly equally likely. (We don't have to talk about individual photons; an analysis of classical electromagnetic waves reflected from a moving mirror will lead to the same prediction for the blue shift and red shift.)

OK, so classical physics makes blue shift and red shift pretty much equally likely. However, what they observed is that the blue shifted photons start to disappear much more quickly than the red shifted ones, thus confirming a prediction of quantum mechanics and clashing with the prediction of classical physics.

In the fourth comment, Vlamis thanks Carroll for a clarification concerning the compatibility of QM and SR. However, look at this fifth comment by Doc C:

That’s like saying a grain of salt is sodium and chloride. It’s not, it’s sodium chloride. Quantum behavior describes the foundations of our world, but our world is not its quantum foundations. Perhaps there are constraints on the classical manifestations of the quantum foundations, but the classical world emerges from its quantum foundations. The quantum foundations are not isomorphic with our classical world.

Well, this is the kind of a completely incoherent babbling by a layman who thinks he's very smart and philosophical but the babbling really makes no sense whatsoever.

The relationship between quantum mechanics and classical physics has nothing to do with sodium, chlorine (the element is not called chloride!), or sodium chloride – except that quantum mechanics is clearly needed for a realistic understanding of the reason why sodium and chlorine bind to produce salt.

I won't accuse Doc C of thinking that the quantum-classical relationship is equivalent to the appearance of a molecule of salt. He clearly wanted to say that the "whole is different from the union or the sum of the components". Well, in some aspects it is different, in some aspects it is the same thing. However, the slogan "the whole is different from the sum of the components" has nothing to do with the classical-quantum relationship, either. The sentences by Doc C are just memorized slogans that have nothing to do with each other.

The sentence "Perhaps there are constraints on the classical manifestations of the quantum foundations, but the classical world emerges from its quantum foundations." proves, I believe, that Doc C doesn't understand that quantum mechanics isn't just a "constrained classical physics". It's a totally different theory. The predictions of the right theory, quantum mechanics, aren't a special case of predictions of a classical theory. Instead, they're often predicting things that no classical theory could ever predict. The violation of Bell's inequalities is an example.

His final sentence "The quantum foundations are not isomorphic with our classical world." makes it even more clear that he misses the whole point – starting from Carroll's title "There is no classical world". It is true that quantum mechanics isn't isomorphic to classical physics but what's totally wrong is the word "our". Our world is simply not classical so every sentence about the foundations using the sequence of words "our classical world" proves that the author of the sentence is a moron.

Moreover, while we may distinguish the real world from its description, it is true that the real world is isomorphic to quantum mechanics (or a particular quantum mechanical theory) in the sense that every question about the real world is isomorphic to a question about the quantum mechanical theory and the answers agree.

In the sixth comment, Bob wrote:

How does the ground state survive the laser? And, like Joe above, why isn't the energy lost by the red-shifted light enough to allow the blue-shift in both the quantum and classical cases?

Well, the ground state doesn't necessarily remain the state of the mirror at all times. The mirror can get excited. But just like an atom, it will eventually (quickly) fall back to the ground state unless any conservation law forbids such a process. At zero absolute temperature, everything wants to be in the ground state. At a higher temperature, the vibrations of all the degrees of freedom yield some kind of a thermal equilibrium and a nonzero probability of non-ground states, too.

The mirror is mechanically attached to a structure. In classical physics, its position therefore oscillates back and forth as a harmonic oscillator, spending the same time in the motion against the photons and away from the photons. I have already discussed it. In quantum mechanics, the position of the mirror is a position in a quantum harmonic oscillator and the energy carried by this quantum harmonic oscillator is quantized. Only certain transitions are possible. Transitions between discrete energy levels (like in atoms) is what quantum mechanics gives us instead of the mirror-photon classical collision. (The classical limit emerges from the interference between many energy levels when they become dense enough.)

The cooler the system is, the more correct it is to assume that everything sits in the ground state most of the time. When a degree of freedom is excited so that the system is no longer in the ground state, the excess energy is going to be communicated to a random (probably different) place or places, and the system (the mirror) will return to the ground state.

Concerning the second question, the probability (calculated in quantum mechanics, i.e. one in the real world) that the mirror finds itself in a particular (e.g. the first) excited state and delivers the extra energy to the incoming photon that would become blueshifted is very tiny. It's much more likely that the extra energy is thrown away by a separate photon (which has a much lower frequency than the incoming photon).

In the seventh comment, mlilom replies to some sentences in Carroll's article

“Nevertheless, you can still meet people (the wrong-minded ones) who are willing to believe that electrons and photons are governed by quantum mechanics, but not that they are governed by quantum mechanics.”

Hopefully, their temperature is not around 0 Kelvin.

Just saying.

Well, nice, but the human beings – and all other objects – are governed by quantum mechanics even when the temperature is higher than 0 kelvins. It is not true that quantum mechanics – the correct theory – modifies the predictions at very low temperatures only. Quantum mechanics modifies everything. For example, it eliminates the Maxwell-Boltzmann distribution for a temperature and replaces it with the Bose-Einstein or Fermi-Dirac distribution. This is a phenomenon at a nonzero temperature.

While a low temperature is good to preserve some coherence which is a good condition for some of the quantum effects to be easily visible (and yes, the quantum distributions materially deviate from the classical ones especially at low temperatures, too), the quantum mechanical theory doesn't cease to hold for higher temperatures, either. And the deviations from classical physics may be manifest at room or higher temperatures, too. For example, the white dwarfs have a high density which means that even at very high temperatures, the Maxwell-Boltzmann (classical) distribution is inapplicable.

And needless to say, at any temperature, we still need quantum mechanics to understand the atomic and molecular composition of the matter around us. Even at the room temperature, the atoms in everything we see are governed by the laws of quantum mechanics.

The eighth comment by Brett:

Good videos. Cool experiment. I don’t want to be banished, but maybe Laurent Nottale deserves a little more attention. I’m honestly all-in on the idea that everything can be described by an increasingly chaotic wave function with increasing scale and vice verse. That’s how every system in nature seems to work.

Doc C,
I would be so pleased to find out you are a professional physicist. My ego would go through the roof.

[Addition in the 9th comment]
By that, I mean I would be pleased that I understood the video and you didn’t. aw snap grrrl.

Brett is right that the comment by Doc C wasn't exactly high-brow but Laurent Nottale's concepts are preposterous, too. You really can't derive quantum mechanics from a classical theory, not even a fractal one. Fractals may be "cool in some sense" but it is not enough to be "cool in some sense" if you want to solve a particular problem, e.g. a problem of classical physics in its efforts to describe some microscopic experiments. Fractals aren't cool enough for that; their coolness has really nothing to do with the paradigm shift that the quantum revolution imposed upon us.

Finally, the tenth comment was authored by Bill Bunting:

I was wondering about the electron, which in my imaginings is an energy surplus consequence of the overlap of the proton and the neutron which pops out upon union and rotates around the cleavage of the nucleus. The fact that it stays in proximity of the PN pair suggests that it is being both repelled and attracted, and the fact that it is rotating around the nucleus (if indeed it does) suggests further that the forces working on the electron are changing position at a speed sufficient to cause the electron to reposition very rapidly as it moves through the Higgs field (which will act to limit that speed).

I plan to collect every PhDComic that is put out and I am hoping that some of them will work backwards to explain how all of this serves to drive chemistry.

I am making sure that our local high schools are aware of this wonderful adventure.

An electron isn't an energy surplus of a nucleus. It is as independent a particle as a proton or a neutron and virtually all aspects of its motion are independent from the mass or energy of the nuclei or the nucleons. This is really the point of atomic physics that governs all of chemistry (and therefore biology and most of the engineering): the nuclei don't participate in the quantum motion that decides about the birth of atoms and molecules. Only electrons do – because they are the lightest ones.

The forces between the electron and the nuclei may be approximated just as the ordinary electrostatic Coulomb force. In particular, the mass of the nuclei (the number of neutrons) doesn't really matter for chemistry (and biology); that's why the different isotopes of an element are virtually equivalent for chemistry (and biology) while they may still be employed as useful markers to trace the fate of atoms (using the methods of nuclear physics). The agreement between such a theory and experiments shows that pretty much everything else may be neglected. We also know lots of corrections that modify the energy of the states by small amounts etc. but since the mid 1920s, physicists could unequivocally exclude any theory that would try to deny that the main force governing the motion of electrons in atoms and molecules is the $Q_1Q_2/4\pi\epsilon_0r^2$ Coulomb force.

The existence and good behavior of atoms does in no way depend on the pairing between protons and neutrons (PN?). After all, most of the hydrogen atoms only possess a proton. Everything else that Bill Bunting says about physics is rubbish as well but at least it's good that he will try to redirect high school students towards animated cartoons on physics. Hopefully not his movies, however. ;-)

New Iranian president

Off-topic but I don't want to dedicate a special article to this comment. There are presidential elections in Iran and they seem to be genuine. If you asked me yesterday, I would have answered that Jalili was likely to win because his image was carefully nurtured by the official Iranian media as I followed them over the years.

But holy cow, Hassan Rouhani seems to have grabbed over 50% (52.5% of valid votes, 50.8% of all votes – big inefficiencies, it seems) right now so that he could win right away, well above the 15% of the runnerup. If he drops below 50%, there will be a second round involving the two top candidates. Needless to say, Rouhani's "conservative" competitor would probably accumulate a greater support in the second round as he would collect most of the votes from other "conservative" candidates' supporters.

This is rather incredible. While he's been Khamenei's voice in certain institutions, he's the opposition-backed candidate and I would say that this trained lawyer, diversely certified theologian, and a former nuclear negotiator is a pro-peace-with-West, free-market advocate who wants to free up the Persian Internet, radio, and newspapers which, he believes, could suppress the corruption. He's probably more libertarian than many politicians we have in the West! ;-) Given these comparisons, and assuming that his behavior in the office would match this rosy picture, I can't imagine how someone justifies continuing sanctions against Persia.

If this guy is allowed to win, I think that claims could be made that Iran is becoming a democracy as we know it. His current frontrunner status is even more amazing for Czechs because we spell/transliterate his last name as "Rouhání". Do you know what's the Czech word for a blasphemy? It's "rouhání" – the words agree including the diacritical marks! ;-)

Czech police raid on lobbyists and politicians

2013-06-14T12:26:00.000+02:00

Trained plasma physicist and Czech prime minister Petr Nečas' government named some prosecutors and created the environment in which they may investigate and efficiently combat corruption and other economic crime on the interface of the public and commercial sectors.

Ms Jana Bradáčová is the "Czech Cattanni" who has energized these efforts and caught David Rath, a prince of the socialist democratic party, with $350,000 in a box from wine.

Mr Petr Nečas with his wife Radka Nečasová, the brunette, and his chief of staff Ms Jana Nagyová who is also his rumored lover. There's a general 2-sigma signal indicating that Czech prime ministers often prefer to abandon their marriage in favor of a blondier woman.

Yesterday, police made a raid on some lobbyists and politicians (mostly nominally center-right politicians) in Prague that some global media consider the greatest scandal in the Czech history. Well, perhaps. Perhaps not.

Some of the numbers are impressive. In the apartments or offices of the suspect folks, they found $7 million or so plus dozens of kilograms of gold (1 kg of gold is worth $50,000 or so). I would bet that most of this wealth has been acquired illegally or, at least, manifestly immorally so that it should be illegal.

It's great that the police works and corruption and other economic crimes aren't easy anymore. On the other hand, it would be great if we weren't becoming a police state and the presumption of innocence were taken seriously. The people who enthusiastically scream "Great! Arrest all of them" simply scare me. In Rath's case, the criminal was caught red-handed and we were told details about the procedure by which he acquired the money. But in this case, at least so far, we haven't been told what the crimes are supposed to be. So at least so far, the situations are simply not analogous.

Ms Jana Nagyová, the director of secretaries of the prime minister – who is rumored to be Nečas' bed partner as well, especially after he divorced his wife in recent weeks (they have 4 children) – is a suspect, too. It was found out (or at least claimed) that she made some military (!) intelligence units spy on the prime minister's ex-wife, too. ;-) She was trying to destroy Nečas' marriage and some discrediting materials were something she was looking for. More seriously, she seems to be connected to the criminal ring in some way. This can be bogus, too.

I think that even if Nečas sleeps with that woman, which is just a rumor, it's not a crime and Nečas himself is innocent. There are clearly many politicians in every party who have been involved in the criminal activity. That doesn't mean all politicians would have to be removed.

Because of all the facts and principles above and others, I find it inappropriate to seriously discuss the resignation of the current prime minister or his government. Needless to say, the social democratic party (and, of course, their closest soulmates in the communist party as well) would use any opportunity and would-be opportunity to try to destroy the government but it's obviously right that the government should struggle to survive because there isn't enough reason to wrap it up – and also because a new social democratic era could be less acceptable than the previous ones.

I am supporting the survival of the current government despite the fact that I am no enthusiastic fan of it or its members or its policies. I don't like that they have raised the value-added tax, that they've been selling some of these left-wing policies as a "pension reform", something that has clearly nothing to do with the taxes and that doesn't have any meaningful "broad vision" either, and so on. But despite these disagreements, one should respect some sensible principles and one of them is that a wrongdoing by a secretary in her private life isn't a fatal wrongdoing of the prime minister himself – unless he is shown to be involved.

There is a lot of irrationality here. The police raid was actually composed of several cases that probably have nothing to do with each other (except for some links to Ms Nagyová). These things are beyond the resolution of a typical angry citizen.

Update: In the afternoon, I was really alerted by the information that an investigator thinks it was a "bribery" for the prime minister to appoint three people to some state-controlled firms or whatever it was (something that he is supposed to do according to the law) in exchange for some political support he needed, probably for the very survival of the government. This is how politicians in any democracy get things through – they have to search for political support and do things that those who support them will appreciate and count as concessions. This is how every compromise is born even though the nature of the concession may have many flavors – but at the end, they're the same thing because one has to do something that the party whose support we need will like (and they will always like it partially because it benefits them or their voters, how it could not be so?).

As Nečas said, when he was constructing the government, he had to offer jobs of the ministers to lots of people to get the support of their parties, too, and so on. They resigned as lawmakers to eliminate the disunity in the party; and they were given some jobs (lower salary than the lawmaker's salary) in some state-controlled companies. The government survived. Was that a corruption? A regime in which a politician wouldn't have to make concessions or "bribe" others in this sense is called a dictatorship because in such a regime, the politician would have to have a complete power. I am scared that over 90 percent of the participants of the discussions on the Internet don't get these simple points. They just don't understand democracy. Or they understand it but they hate it, too. They're waiting for a new Hitler who will save them and eliminate all these "messy things".

Amazon: 3D printers below $1,200

2013-06-13T17:56:00.001+02:00

When Howard Wolowitz bought a 3D printer to print figures of himself, Rajesh Koothrappali, Bernadette Rostenkowski-Wolowitz, and other heroes of The Big Bang Theory, he had to be chastised by Bernadette because it was her money and it was $5,000 of them.

(Incidentally, I made some research of the 1200 XT 3D modeler PRO device that appeared in the CBS sitcom and I am pretty confident that it's a renamed 3D Systems InVision XT 3D Printer.)

But an ex-president of the Harvard Funds and the famous Pirate of Prague, Viktor Kožený, a technological enthusiast who has just gotten access to $22 million of dollars from his (mother's) cottage in Aspen, Colorado but who became a target of a new execution in Czechia at the same moment (he once offered me to become a shadow minister of education which I kindly refused), recommended me to check the rather new 3D Printers Category at amazon.com and I was kind of impressed how accessible those things have become.

The FlashForge 3D printer is available for $1,199. This price can't be approximated by infinity too well. It's an accessible price, I would say. And the reviews look really encouraging, averaging at 4.7/5.0 stars.

The Afinia printer for $1,599 is often claimed to be used by professionals who say that it works perfectly - and it's a professional quality printer. Top software included. Alternatively, you may check some free software right now.

Afinia 3D printer is printing a Klein bottle, a closed non-orientable manifold with Euler characteristic $\chi=0$. Sped up to 1 minute. See a 3-minute presentation of a bigger 3D printer.

Does any TRF reader have real-world experience with 3D printing? If you do, what have you used the gadget for? If you don't, what are your dreams what you could print if you had one? Has someone studied the details of the technology, how it actually works?

International Linear Collider: Technical Design Report out

2013-06-13T10:49:00.000+02:00

Yesterday, as I learned from the CERN website and a CERN press release, the Linear Collider Collaboration (obtained by merging the officials behind ILC and CLIC) has released the ILC Technical Design Report, including a free and colorful 60-page PDF booklet.

It may be meaningful to mention Table 2.1 of that PDF file that describes the planned experiments with their center-of-mass energy.

At $91 \GeV$, the plan is to study $e^+e^-\to Z$, ultraprecision electroweak, and at $160 \GeV$, one may study ultra-precision $W$ mass via $e^+e^-\to WW$. A big part of the early experiments would be $e^+e^-\to Zh$ at $250\GeV$ where this process peaks. This would be good for a precise measurement of the Higgs boson's interactions.

Center-of-mass energies $350$-$400 \GeV$ would reveal top quark couplings from the $t\bar t$ final state, precision $W$ couplings from the $WW$ final state, and precision Higgs coupling from the $\nu\bar\nu h$ final state.

At $500 \GeV$ and $700$-$1000\GeV$, there would be various channels that would search for a $Z'$ boson, Higgs compositeness, Higgs self-coupling, extended Higgs states; and the search for SUSY via the $\tilde \chi\tilde\chi$ pair production of the Majorana particles (e.g. those of the dark matter) and from the pair production of scalar top quarks (stops) $\tilde t \tilde t^*$.

The PDF booklet may tell you a lot about the electric fields, radio frequencies, two detectors that the collider should boast, not to mention a huge list of roughly 100 contributing institutes that harbor 1,000 scientists and engineers who have worked on the report.

There should be 7,000 collisions a second at $500 \GeV$; 16,000 superconducting cavities guiding the beams. The booklet was ceremonially delivered to some VIPs in Europe, Asia, and the Americas. The tunnels are 31 kilometers long and the facility should be very cheap, just $7.8 billion or so, below the LHC costs.

Unrelated, two fun papers.

Don Bennett and Holger Bech Nielsen are trying to fudge a tender for the best gauge group in the Universe, with a pre-decided winner who should be the Standard Model. I agree with the general spirit that Nature may have declared such a job contest (a vacuum selection mechanism) but I think that its criteria were probably less contrived than the functions-of-Casimirs-based criteria in this paper. I also think that the job contest organized by Nature chose not only the gauge group but all other properties (matter spectrum and the parameters following from the right stringy compactification) of the Universe around us at the same moment which means that I tend to believe that any job contest that only chooses the gauge group is probably unnatural, contrived, and ultimately invalid.

Two Indian authors are trying to claim that the light, $5$-$10\GeV$ particle of dark matter, may have already been near-discovered from the 1970s and 1980s due to eight of the so-called Kolář events in India (I couldn't resist to put the Czech diacritical signs because it's a rather standard Czech name).

Murry Salby: CO2 is the integral of temperature

2013-06-12T08:29:00.001+02:00

...in the past, on short timescales, it has therefore fluctuated rapidly...

Honza [=Jan] U. sent me the following one-hour April 2013 talk by Prof Murry Salby of Australia's Macquarie University:

This astrophysicist and atmospheric scientist has a rather impressive publication record. At the beginning, I was a bit discouraged by Pierre Gosselin's summary that suggested that Salby was making some widespread elementary errors about the direct attribution of CO₂ emissions according to their isotopic composition (the extra CO₂ we see in the atmosphere generally has a very different composition than the CO₂ when we emitted it, because the carbon is being quickly recycled all the time while chemistry doesn't care about the differences between isotopes but it's still true that our additions of CO₂ have increased the CO₂ concentration).

But I was wrong, Salby isn't doing these particular trivial mistakes and when I ultimately listened to the talk, it looked rather impressive.

He employs various types of statistical models, Fourier transformations, and other things to decode the relationships between CO₂ and the temperature. Of course, the temperature is mainly the driver of CO₂ and CO₂ follows – to say the least, that's the dominant relationship during the glaciation cycles (the time scales from tens to hundreds of thousands of years).

Those things wouldn't be new and I wouldn't listen to another 1-hour talk that just discusses whether CO₂ was the cause or the consequence during glaciation cycles. Of course it was the consequence. Whoever still acts as if he were misunderstanding these basic issues is either a hopelessly brainwashed moron or an amazingly dishonest demagogue or both.

But Salby said much more than that.

He argued that the anomalous CO₂ concentration may be approximated as the integral of the anomalous temperature, \[

\Delta\,{\rm conc}(CO_2) = \alpha \int \dd t\,\Delta T

\] which sort of explains why it seems to be rising so smoothly (if we ignore the nearly periodic seasonal variations). But Salby has also presented some evidence that the ice record heavily underestimates the fluctuations of the CO₂ concentration, especially the high-frequency (short-period) oscillations that occurred a long time ago. If that's true, it's pretty likely that concentrations above 400 ppm may have been rather mundane even before the industrial activity.

Using the Fourier methods, he argues that there is a phase shift of 90 degrees between the temperature and CO₂ pretty much at all frequencies. I am not quite seeing how this may be true because at least in the glaciation cycles, i.e. at the 10,000-year time scale, these two quantities are pretty much in sync. How does the phase shift move to 90 degrees for shorter time scales?

And his discussion of the different isotopic composition (C12 vs C13) of the fossil fuels and the present plant life is sophisticated, not the kind of silly caricature I was led to expect. At any rate, Salby concludes that the excess CO₂ is caused by the integrated or accumulated positive temperature anomaly in 1920-1940 and 1980-2000 or so and these positive anomalies may be interpreted as noise, not results of any trends.

That sounds nice except that I think it's obvious that the CO₂ we have added to the atmosphere has led to some increased CO₂ concentrations and the latter increase is comparable to 50% of the former (airborne fraction etc.) – it's not negligible. It doesn't matter that there are 50 times more important contributions to the CO₂ atmospheric budget as well. Despite these dominant contributions, a small surplus simply can't become completely invisible.

If you were thinking whether you should listen to that talk, my recommendation is probably Yes. Despite the fact that he is trying to deny some obvious facts – if I understand the discussion about the attribution of an elevated CO₂ well and if I am right about its imperfections – he is also saying lots of new things and offering many sophisticated methods that you may want to know about.

At the end, Salby offers some criticisms of the climate models that I only partly agree with. Concerning the agreeable conclusions, he says that the prevailing climate models show CO₂ and the temperature essentially as the same thing; in the real world, they're not the same thing at all. These two claims – and their paramount contrast – are self-evidently true.

To mention the propositions I don't quite share, he says that theories can't ever be tested against the past data; tests of predictions of the future are always needed. I disagree with that. It's a historical coincidence whether some data were collected before a theory was written down or after that. A theory is always constructed or chosen according to the data in the past and then it gives predictions for other phenomena as well. Those phenomena may be data to be collected in the future but also additional data that may be collected about the past. Regardless of the timing, such data may be used to strengthen or weaken our confidence in the theory (or rule it out).

See also replies by MeteoLCD (more detailed review than mine!), Anthony Watts' 100+ commenters, The Hockey Schtick, Climate Depot, Tall Bloke, and – from the crazy side of the aisle – John Cook (I agree with some of the criticism) and Deltoid who calls Salby "unhelpful" (for "the cause") LOL. ;-)

Finding and abandoning incorrect general relativity lore

2013-06-11T19:51:00.000+02:00

While I was buying and installing my new fridge, I kept on burning my brain by analyzing various refinements and implications of the paper by Maldacena and Susskind.

Some business with the M2-brane topology change and entanglement looked too obvious to me so I returned to the question how do the black hole exterior and interior really interact. The burning of the brain is composed of various steps that combine and recombine analytic continuation, diverse choices of coordinates, unusual ways to redefine the connectedness of the spacetime, and connections between previously disconnected regions through the complexified spacetime.

At each step, I try to ask not only HOW does it work but also WHY a particular trick that looks clever at a given moment should be picked and WHETHER it is inevitable or unique. Some of the partial conclusions are more convincing than others but I don't want to waste your time with an incomplete picture.

Instead, let me mention that we're probably victims of some bad habits and ultimately invalid lore related to the way how we think about certain issues in general relativity.

What do I mean?

General relativity is composed of the equations that are locally valid, Einstein's equations, and one may derive them from the equivalence principle and/or the diffemorphism symmetry that is needed for a consistent, ghost-free theory of spin-2 fields. We know that Einstein's original equations include the leading terms in a derivative expansion but there may be higher-order operators, too. All this stuff seems obvious and undeformable.

But we're also making some conceptual and "global" assumptions which may be wrong – and this wrongness may be especially harmful when one considers the black hole information puzzle and related topics.

General relativity is capable of producing spacetimes of nontrivial topology and the topology is a classical property of a spacetime. Therefore, it's been implicitly assumed that the discrete data defining the spacetime or space topology are observables that are represented by linear operators in the quantum theory.

Maldacena and Susskind have pretty much completely convinced me that this can't be the case, however. A spin-up electron here and a spin-down electron there, $\ket{\uparrow\downarrow}$, that propagate on a flat spacetime seem to be eigenstates of the "topology" operator with the "trivial topology" eigenvalue. The same seems to hold for $\ket{\downarrow\uparrow}$. If the "space topology" operator were linear, it would also obey\[

(\hat{\text{space topology}})\cdot (\ket{\uparrow\downarrow} - \ket{\downarrow\uparrow}) = (\text{trivial topology}) \cdot (\ket{\uparrow\downarrow} - \ket{\downarrow\uparrow}) \text{ NOT!}

\] However, the correct eigenvalue is different, Maldacena and Susskind argue:\[

(\hat{\text{space topology}})\cdot (\ket{\uparrow\downarrow} - \ket{\downarrow\uparrow}) = (\text{topology with an ER bridge}) \cdot (\ket{\uparrow\downarrow} - \ket{\downarrow\uparrow}).

\] (Please, open the mobile version of this page to see the whole equations; I don't want to change them or divide them to several lines.)

After all, this singlet state is the simplest quantum state that lives on the background with a single Einstein-Rosen bridge. So there's no linear operator that would count the Einstein-Rosen bridges. It's not a good observable. You can't use the number of ER bridges as a quantity that defines coarse-grained histories, e.g. in the Consistent Histories approach to quantum mechanics. In other words, the state $\ket{\uparrow\downarrow}$ isn't orthogonal to the singlet state above: they're not mutually excluding although the former seems to be living on a bridge-free spacetime while the latter is living in a spacetime with a bridge.

Note that there's nothing wrong about the non-existence of an operator – observable – that would count the Einstein-Rosen bridges in a simple way. The bridges may be very thin and thin bridges are examples of those that are strongly affected by the "Planckian" details of a theory of quantum gravity. More generally, there isn't any clear operational method to determine the spacetime topology. A strategy to "see" a wormhole is to look for clumps of information and patterns that are repeated in two regions – but that's the same thing that defines correlations or entanglement. Entanglement of a state isn't associated with an observable, either.

You should notice that all the childish proposals to construct a theory of quantum gravity such as loop quantum gravity, causal dynamical triangulations, and so on are incompatible with the Maldacena+Susskind insight (not that it is the first lethal disease that has killed these stupidities, far from that). Why? Because they construct a spacetime (dreaming about its being large and nearly smooth) that clearly has some combinatorial properties and some topological invariants may be clearly extracted from their preferred basis of spin networks and other silly animals they use. So they have linear operators of "space topology".

It's easy to see why these approaches to quantum gravity have this property – which we now believe to be a pathological one. They have it because they belong among the naive models of quantum mechanics that start with a preferred basis and observables for which all the basis vectors are eigenvectors. But such theories are extremely unnatural as quantum theories because quantum theories don't come with any preferred bases or preferred operators. Viable quantum theories always offer us many different operators that don't commute with each other – which also implies that bases constructed from the eigenvectors of one set or another set are different bases.

We have to jettison this excess baggage. In quantum gravity, there aren't any linear operators that would honestly count the number of Einstein-Rosen bridges in the spacetime or other things. We must be careful about this incorrect assumption. It's a trap.

Bridges that invite you to count them with a linear operator are probably not the only trap. I became convinced that there is something wrong about the way how we think of black hole singularities.

The smart contemporary relativist – smart according to the "mainstream" – knows that black holes are defined by their event horizons. The event horizons is what separates the black hole interior from which nothing can escape – and that's why the black holes are black. And it's true. But...

The singularity plays a secondary role. That's where the infalling observer is finally killed. Things get sick around the singularity, the low-energy or low-curvature effective theory breaks down. One needs the full theory of quantum gravity but it's generally believed that it can't help us to eliminate the singularity as a violent and irregular end of the spacetime, anyway. The existence of the singularities is a robust conclusion of the low-curvature effective equations of motion that more accurate dynamical laws can't change because the singularity is too localized, after all. And it's true as well. But...

Let me say what is the problem. Singularities are hard to be avoided but we generally assume that they don't spoil the dynamics elsewhere in the spacetime. After all, all singularities are covered by event horizons so they can't spread the illness outside these black holes etc. Penrose strengthened this ideology – and yes, it's an ideology, not robust science supported by evidence – by the Cosmic Censorship Conjecture which we now kind of know to be wrong even in the most weakened versions you may think of. Classical general relativity can't save us from the singularities whose impact has the potential to be harmful. So we have to deal with them, after all.

My impression is that we're doing something wrong with the singularities and this error may be shown to be responsible – at least in one scheme of attribution – for some of the confusion we're still seeing when it comes to the black hole information puzzle.

So I was comparing how we imagine a well-defined problem in semiclassical (or more accurate) general relativity with quantized fields on a background with a computational framework that has much higher standards of physics rigor, namely with calculations on the string theory world sheet. The semiclassical gravity on the background of an evaporating black hole has a singularity and fields become crazy at that point but we don't care. Because of causality – something we believe to be "inherited" from the special relativistic core of the classical general relativity – the Armageddon near the Schwarzschild singularity won't spoil anything else.

Except that we have sort of known for quite some time that this strict version of locality doesn't exactly hold in quantum gravity. Can't the required non-local behavior be blamed upon the singularity? I guess it can.

Beginners who learn string theory are also told about the possible boundary conditions at the stringy endpoints. The requirement is that the boundary terms in $\delta S$, the variation of the action, have to cancel. Otherwise we would just not get a consistent theory. What the boundary conditions are always matters. So we learn that there may be open strings – with Neumann and/or (as Polchinski and others taught us later) Dirichlet boundary conditions – or closed strings with some kind of periodic boundary conditions (the periodic conditions may also be twisted because closed string states may exist in the twisted sectors, too).

But we never ignore this problem in string theory. We don't sweep it under the rug.

Our habits in general relativity are different. Replace the world sheet with a spacetime – a background spacetime with an evaporating black hole. It has some boundaries, the null infinities (SCRIs), the $r=0$ "line" (an artifact of the spherical coordinates), and the black hole singularity. If these boundaries of the Penrose diagram were boundaries of a world sheet, we would insist that consistent boundary conditions cancelling the boundary terms of $\delta S$ are picked. In general relativity, we seem to be more sloppy. After all, we're not afraid of any singularity because of the causal protection, are we?

So I began to think that we're simply obliged to solve these problems. We're solving them sort of correctly – analogously to the open strings – in the case of the null infinities and the $r=0$ line (well, lines – before and after the black hole evaporates). The problematic boundary of the Penrose diagram (essentially the spacetime) is the singularity.

In their 2003 paper called Black Hole Final State, Maldacena and Horowitz proposed some "final boundary conditions" at the Schwarzschild singularity. Effectively, the singularity would behave as yet another open-string-like boundary, a mirror of a kind. It led to lots of puzzling threats for causality and at least some complicated transformation had to be inserted next to this "mirror" for the behavior of the object not to be self-evidently acausal or teleological.

Today, I started to think that the right boundary conditions are different than those in the black hole final state: one must define sort of closed-string-like boundary conditions for the spacetime. Most likely, the region near the singularity has to be analytically continued to the complex values of coordinates and connected to... the future null infinity where the Hawking radiation appears. That's a more accurate Ansatz for the "bridge" by which the early Hawking radiation may be connected to the black hole interior.

I started to believe that a physicist who wants to properly define quantum field theory or a form of quantum gravity on a spacetime background (and I mean in the Hamiltonian form, using spacelike slices) is obliged to fix the problems with the boundary conditions in some way. This way is perhaps not unique but it's a part of his definition of the "consistent histories" and quantum field theory (or its extension) on a curved spacetime gives him the tools to calculate the probability amplitudes. In some broader sense, all the frameworks are physically equivalent even if they assume a different background spacetime topology: we know that perturbations of the background spacetime may not only change the detailed metric but even the topology (at least, they may add Einstein-Rosen bridges if they're entangled).

So the future null infinity probably has to be connected to the singularity through the complexified spacetime in some way, to cancel the boundary terms in a way that is remotely analogous to the cancellation in the case of the closed string – periodic boundary conditions. When it's done, the radiation that reaches the null infinity may probably influence the behavior inside the black hole – and possibly also outside the black hole but close $O(R)$ enough to the horizon.

Maybe we're allowed to connect a black hole interior's to any other black hole's interior to create a consistent background. We shouldn't be afraid of starting with complicated spacetimes with wormholes etc. because – in a striking contrast with another myth – wormholes may be undone by excitations added upon them, too. In particular, the ER bridge may be twisted by an angle before it's connected and the superposition over all angles produces an unentangled configuration - two isolated pure-state qubits, in our example. So the wormholes may be undone by excitations (they may be created and destroyed, like any object in a QFT-like theory) which means that we're probably not losing any generality by assuming that two black holes' interiors are connected.

This is a preliminary conclusion that may mutate later but at least once, I wanted to provide you with a snapshot of the partly crazy, partly trivial thoughts running through my biowires. And now I am going to restart the PC to install the June 2013 batch of Windows patches. ;-) This text will be proofread later, perhaps after a crime film on TV (done, but not too carefully because I don't expect the serious readership of this blog entry to be too numerous).

Bohr model: 100 years ago

2013-06-09T07:24:00.000+02:00

One hundred years ago, in July 1913, when the author was 28 years old, Philosophical Magazine received Niels Bohr's manuscript on his model of the atom. Happy birthday. Both 25-page papers are available in English here:

On the Constitution of Atoms and Molecules I
On the Constitution of Atoms and Molecules II

Bohr's model was wrong in details – and he should have been able to see it – but the papers clarified many aspects of nuclear and atomic physics. Bohr referred to Rutherford, Thomson, and others. But only after Bohr's paper, nuclear physics started to be carefully distinguished from atomic physics. For example, Rutherford received the 1908 Nobel prize in chemistry. These days, we would surely not think that nuclear physics is chemistry.

Bohr's model was essentially classical physics with the ad hoc assumption that the periodic orbits were restricted: $\oint p\,dq$ had to be in $2\pi\hbar\ZZ$. Quite accidentally, this assumption implied that the allowed total energy of the electron in an otherwise Keplerian orbit around the nucleus agrees with the energy extracted from the hydrogen emission and absorption spectrum (or from quantum mechanics that wasn't born yet).

Today, we know it was a coincidence. The correct spectrum must be extracted from quantum mechanics that was developed more than 10 years later (perhaps, they should have seen it faster?). The hydrogen atom happens to be sufficiently simple and solvable and its energy levels $E_0/n^2$ just happen to agree with the levels that you obtain by the classical model restricted with a simple additional constraint.

The second Bohr's paper is dedicated to more complicated applications of Bohr's theory to other atoms and molecules. He should have seen that those things couldn't really work. Already the helium atom is a messy object and the classical three-body problem – with a nucleus and two electrons – is in some sense even messier than the quantum mechanical problem because the trajectories really don't want to be periodic.

We should also notice that Bohr had to overcome some additional steps towards quantum mechanics that was born in the mid 1920s. These steps went beyond the quantization of the orbital parameters. In particular, he had to realize that the transitions during which photons are emitted are governed by a nearly quantum logic. The electron that is changing its state of motion must be guaranteed that the new orbit will be allowed – it will obey the quantization rule for the orbital parameters. This requirement is almost directly extracted from the experimental data on spectroscopy but because it contradicts the classical logic so much (in classical physics, you would need an electron that plans the future, a mechanism that is sort of acausal, while the transition is perfectly causal in quantum mechanics), Bohr had to be courageous to propose it.

After some time, the correct theory was found and the reason why Bohr's theory looked good was understood. Some patience was needed. We should learn a lesson or two from these historical episodes.

Of course, many questions remained open even after 1925. For example, what is the glue that holds the nucleus together?

No, it has nothing to do with QCD or Gross or Wilczek or Politzer. Check the video above about the newest research which finally told us what is the answer. ;-) Via Honza U.

Toshiba's Westinghouse claims to be the Czech nuclear frontrunner

2013-06-08T18:56:00.001+02:00

While the Czech media discuss politicians' opinions on whether we need an expansion of the Temelín nuclear power plant at all – because of the expected drop in coal and gas prices (due to shale oil) – the Japanese investigative journalists claim that they already know that we need it and the Japanese industrial group is likely to win.

Shinzo Abe, center-right Japanese PM

The leading Czech power utility, ČEZ, will decide whether Temelín will be expanded and who will get the $10 billion contract in Fall 2013. The French state-owned Areva was eliminated in a previous round because it was claimed that some basic conditions weren't fulfilled – Areva is trying to appeal but the chances are slim – which leaves us with two candidate projects: American and Russian. Being right in the middle of American and Russian interests (or, in some contexts, German-Austrian and Russian) is something that a genuinely central European country like ours is intimately used to.

Well, more precisely, they're a Czech-Russian plan and a Japanese-American one. The Czech-Russian group is composed of Gidropress (RU), Atomstroiexport (RU), and Škoda JS (CZ), while the Japanese-American project is proposed by Westinghouse (US) which belongs to the Toshiba Group (JP).

Nikkei.com, a leading Japanese newspapers, claimed that "Toshiba Group [Is] Closing In On Czech Nuclear Order". The project got the highest evaluation in a pre-screening process, AFP tells us.

It's suggested – although I don't quite understand the evidence etc. – that Toshiba Group will be closer to victory also because a group of Central European countries will welcome a new participant at the V4 summit (the Visegrad Group, composed of Czechia, Slovakia, Hungary, and Poland). Who is it? Is it Slovenia who is trying to join but it may become an outfit for its being so uncritically pro-EU (even more so than Slovakia)? ;-)

No, the new Central European country is called Japan.

On June 16th, while going to the G8 summit in Northern Ireland, Shinzo Abe will stop in Poland to strengthen the Japanese nuclear exports. According to the Japanese sources – not confirmed by the Czech diplomats at all – Abe should sign a treaty about some nuclear cooperation with the new Czech president Miloš Zeman. This would be sort of incompatible with claims by a correctly self-described fa9g0t and, shamefully enough, newly appointed professor Mr Putna (not by Zeman, though) who caricatured both Zeman and his predecessor Klaus as Putin's puppets. Zeman apparently has no trouble with a Russian defeat in this contest.

Any group of high school kids in Japan can easily perform Antonín Dvořák's New World Symphony. ;-) Another part, one more. Holst's Planets, Rachmaninov, and other things from them.

I have no robust knowledge about the projects and their advantages or disadvantages. There are obvious reasons why we could think that the Japanese-American project is technologically better and/or safer although I surely don't think that the Russians are losers when it comes to nuclear energy. The Westinghouse option is worse for the Czech economy, too. If we will talk about Westinghouse as the only candidate at some time, I find it natural for the Japanese and their American employees ;-) to build nuclear power plants in other countries rather than Japan. Japan is overfilled with people which makes it necessary to eliminate even very tiny risks and the frequent earthquake under their soil create the risks very often, too. Despite widespread misconceptions, there hasn't been any nuclear catastrophe in Fukushima at all but perception is everything and most people are too stupid to distinguish an earthquake or tsunami from an explosion of a power plant; only the former, not the latter, produced casualties in Japan.

In Czechia, we don't have any earthquakes to mention, the population density is lower, and the public perception of nuclear energy is good enough so that a nuclear power plant could be rather easily built beneath the Prague Castle, if needed. ;-) The question whether two new reactors are really needed it the toughest one, I am afraid. But one thing is almost certain: Nature wasn't generous enough to allow Czechia to participate in the shale gas boom if there's gonna be one.

Maldacena, Susskind: any entanglement is a wormhole of a sort

2013-06-08T06:49:00.000+02:00

...more precisely, EPR is equivalent to ER...

Juan Maldacena and Leonard Susskind wrote a cool paper attacking the horizons of our current understanding of quantum gravity which may look convoluted if not entangled to many readers, which may swallow your attention like a black hole, and which is called

Cool horizons for entangled black holes.

I suppose that the paper was created after Juan Maldacena explained to Lenny Susskind why his recent pro-firewall paper was wrong. Both Maldacena and Susskind have thought about similar things for quite some time but there are many reasons – including my knowledge of the genesis of this modest paper – why I think that the active claims and "choices of the right answers" are Juan's, not Lenny's. ;-)

Update: See also John Preskill's enthusiastic review of the paper.

Just very recently, Lenny was very confused about the firewalls and thought that the AMPS arguments have made firewalls inevitable. The new Maldacena-Susskind paper is clearly an anti-firewall paper. Well, they actually conclude that the firewalls don't have to be there but there may, depending on the decision of a female overlord whose identity will be partially clarified below...

Healfix finds the paper controversial, either wrong or the first salvo of a completely new revolution. I don't. The paper is cool but it's a totally natural continuation of the state of the affairs as we have known it for quite some time. It builds on Werner Israel's thermofields (Werner Israel is an ex-collaborator of our Gordon Wilson), Maldacena's 2001 comments about the "pair of CFTs" description of the eternal AdS black hole, and some ideas about "entanglement as a topology change" that I recently associated with Mark Van Raamsdonk although many people, including your humble correspondent, have been thinking about the same paradigm for many years. Ryu and Takayanagi have contributed an influential 2006 paper about the entanglement in the black hole context.

The ideas linked to thermofields and the doubling of degrees of freedom were recently mentioned and exploited by the Raju-Papadodimas paper but again, it's true that a dozen of credible researchers or so has thought about these matters in this way.

I need to mention that Juan Maldacena's image among those who have a clue about theoretical physics is so stellar partly because he has never written a paper – and perhaps a sentence in a paper – that wouldn't be supported by rock-solid evidence. (Well, Horowitz-Maldacena's intriguing yet speculative "black hole final state" may be an exception to the rule but the logic of that paper may get revived due to this Maldacena+Susskind development, too.) And this paper is no different. Comments by folks like Sean Carroll that these authors may afford to write rubbish because they have tenure has nothing to do with the actual reality. These is completely false and sort of disrespectful.

These folks have way too much to lose – their top status in theoretical physics, acquired by having written systematically valid and important contributions to physics. Carroll has never cared about the validity or quality of his papers and claims which is why he's respected as a physicist by the know-nothing popular bullshitters only but Maldacena (in particular) is a genuine scientist, the ultimate cautious researcher who is, despite these tough constraints, still able to ignite revolutions at some points and it's no coincidence that he was among the inaugural recipients of the $3 million Milner Prize.

Both authors are giants of dualities and equivalences so the main idea of the paper may be expressed as a new kind of duality – the existence of two seemingly different but ultimately exactly equivalent descriptions – which may be expressed by their formula\[

ER = EPR.

\] This equation says that the Einstein-Podolsky-Rosen entanglement is the same thing as the Einstein-Rosen bridge. You may be tempted to cancel ER and disrespectfully deduce that Podolsky is equal to zero. However, you shouldn't forget that the equation above is one of a multiplicative rather than additive sort so the right conclusion is that Podolsky is the number one. ;-)

The new paper starts with some comments you have seen on this blog many times: EPR-style entanglement doesn't represent any genuine non-locality. It doesn't allow you to send any genuine information to spacelike-separated regions of the spacetime i.e. faster than light. Correlation isn't causation; quantum mechanics predicts correlation for EPR-style experiments but the correlation/entanglement is a consequence of the objects' mutual contact in the past when the state of the whole system was prepared, not a consequence of any action at a distance in the moment of the measurement.

There is another concept that doesn't allow you to send the information superluminally although you could naively think that it can: the Einstein-Rosen bridge. This is a technical name for a special wormhole, one that is constructed by gluing and/or maximally extending the vacuum solutions of Einstein's equations of general relativity i.e. things similar to Schwarzschild's solution for an empty and neutral black hole.

Off-topic: Lisa Randall's 19-year-old lookalike, Ms Sabina Křováková of the Northern Bohemian town of Děčín [Dyeh-cheen] won the 2013 Czech and Slovak Superstar.

A reason why this sort of a "non-traversable" wormhole doesn't allow any standard faster-than-light communication (at least not a permanent one) is simply the black-hole-like appearance of the exterior of the wormhole (on both sides): you may only catch the would-be information that has propagated through the wormhole if you actually jump into the black hole but in that case, you de facto commit suicide and give up the right to exchange the information forever. Once you jump to the black hole, you may say that your position with respect to the exterior asymptotic region of the spacetime is "confusing". You are somewhere in between the original two widely separated places, not in the vicinity of either of them, so your perceptions shouldn't affect the question whether the two separated places may exchange the information. They cannot and you don't belong to those places anymore!

So both ER and EPR are concepts that could naively allow you to send the information faster than light; but both of them actually refuse to do so. They share these two properties so they could be the same thing. Of course, it's not a proof that they're the same thing which is why Maldacena's and Susskind's claim that they are actually the same thing both non-obvious and non-vacuous contribution to physics if it is true. And they have some more detailed evidence that it actually is true.

Whenever there are two objects that are entangled, one may view this entanglement as the existence of a wormhole of some kind. However, in most cases, such a wormhole is Planckian, so to say, and it requires the full theory of quantum gravity – going well beyond the effective long-distance theory similar to general relativity – to be properly studied. (I can't resist to think about the thin handles that may be added to M2-branes modeled by Matrix theory without changing the state described by the noncommutative geometry; their spacetime wormholes must be analogous to these "world volume wormholes".) They admit so: they reinterpretation of the entanglement as an Einstein-Rosen wormhole may often be just an academic formality that doesn't allow you to exploit the useful properties we like to associate with large and thick wormholes.

On the other hand, they accumulate quite some evidence that a greater number of examples of entanglement than what you might think may be described in terms of the Einstein-Rosen wormhole that is really large and classical and unquestionably deserves the title.

In particular, they suggest that once a black hole evaporates one-half of the original entropy, i.e. after the Page time when we know the early radiation to be almost maximally entangled with the remaining black hole, one automatically gets the "thermofield-like" doubling of the degrees of freedom – doubling of the number of black holes. The early Hawking radiation may be interpreted as one of the two black holes that is connected (after some transformation of its degrees of freedom) to the remaining, self-evident black hole by the Einstein-Rosen bridge.

The authors claim that this has consequences for the perceptions felt by an observer who jumps into the remaining black hole: his perceptions – which may include the firewall-like death near the horizon – are actually affected by the decision what some other observers do with the early Hawking radiation! After all, manipulating with the early Hawking radiation should be interpreted as processes "somewhere inside the wormhole" so these processes may be thought of as appearing "geometrically close to the black hole interior" because this is where the second exit from the wormhole resides!

Whether or not such an influence of the "experimenter measuring the early Hawking radiation" on the "infalling observer" violates any notion of locality and how strongly is a subtle question that requires you to be careful. Clearly, some locality as defined strictly by classical general relativity (and assuming the non-wormhole relationships between events in spacetime!) has to be violated because the measurements of the early Hawking radiation can't be connected by any time-like trajectory with the events in the remaining black hole interior. However, they are connected in more general ways.

Even if the infalling observer is able to miraculously find out something about the activities done by very distant, seemingly spacelike-separated experimenters who measure the early Hawking radiation, it doesn't imply any real paradox that we may derive from faster-than-light communication simply because the infalling observer has no way of communicating his perceptions to the folks outside the nearby event horizon.

We shouldn't overstate the reasons why we believe principles such as locality. We believe them because in combination with the Lorentz invariance, faster-than-light communication would be equivalent to the changes of the past and closed time-like curves that would lead to contradictions. However, if we consider more general situations with "doomed infalling observers" whose doomed fate allows us to avoid the paradoxes, the original evidence in favor of the strict locality really evaporates.

The observer on one side of the Einstein-Rosen bridge may control the perceptions of the other if she acts quickly enough; a section of the paper is dedicated to the question what this condition means. It seems that they want to apply these considerations to the experimenter who manipulates with the early Hawking radiation, too. She has some power over the poor observer who falls into the remaining black hole after the Page time. Don't forget that while feminism empowers women (yes, all the observers who control others are female in the paper), it comes with a responsibility, too. ;-)

A nice thing about the paper is that it passes all tests of "absence of basic misunderstandings". The authors don't seem to suffer from any confusion such as a misunderstanding of the foundations of quantum mechanics. I have already suggested that this virtue results from Juan Maldacena's genes incorporated into the paper. (Lenny, despite his being so utterly sensible, has already written some papers boiling down to a misinterpretation of the postulates of quantum mechanics.) In fact, I believe that Juan Maldacena is flawless in this respect – he would never write a paper that makes an error in the foundations or interpretation of quantum mechanics or any other topic that one could include among the "standard undergraduate or graduate course material". I believe he suffers from no confusions that are so widespread in the "popular science literature".

To say something stronger, much of the paper seems obviously right. Quantum mechanics is used fully up to the limits and they struggle to interpret any dynamics – including any sort of entanglement – geometrically, as a bridge of a sort. That's right because after all, string theory unifies all forces and matter with gravity so everything may be viewed as a generalized gravity or generalized geometry.

At the same moment, there's quite some potential for this line of reasoning to run much deeper than that. Various folks including Edward Witten and Cumrun Vafa have explicitly said that while they didn't expect any true deformation to be ever made to quantum mechanics, they could imagine a future revolution that will unify the postulates of quantum mechanics with all kinds of geometry that appears in physics (especially the spacetime geometry) in a new, more intimate way. The geometrization (conversion to a bridge) of any entanglement in physics could lead us to a very tangible realizations of those ambitious visions.

And that's the memo.

Pros and cons of the U.S. surveillance program

2013-06-07T17:15:00.000+02:00

It has been revealed that the FBI and NSA are using the Patriot Act to monitor pretty much all telephone calls and media files drifting through 9 major Internet companies including Apple, Google, and Microsoft. Obama says that those things are in the context of the fight against terrorism. Some key officials responsible for these formerly secret programs have criticized the... leak.

I was sort of pleasantly surprised by the New York Times editorial

President Obama’s Dragnet (via NewsMax)

which sort of concludes that the Obama administration has lost all credibility on this issue. The surprise is nice not because I am sure that I agree with the Grey Lady – my feelings are mixed – but because I would agree that the newspaper's approach to similar questions has been consistent throughout the Bush and Obama administrations.

Some partisans who have criticized Bush for certain things suddenly get unbelievably silent when the same things are being done by Obama but the New York Times doesn't seem to belong to this hypocritical club. I know that many fellow rightwingers really despise the Grey Lady but for me, it still represents the kind of healthy and manageable (nearly) centrist America that I first met in the late 1990s. Well, mostly.

Needless to say, some people find it creepy and unacceptable whenever their personal data are accessible to some third parties – even if the third parties are just Silicon Americans (I mean computers and similar creatures who use transistors to think). Well, I personally don't share these emotions but I agree that even if the reason for concern is purely psychological, those who find it creepy have the right to use the mechanisms of democracy to promote their opinion that these things shouldn't be happening.

I have said that a similar monitoring, as long as it is guaranteed that it's illegal to abuse it, doesn't scare me. Imagine that you have some private data or habits on the Internet or photographs etc. that you don't want to publish. Why do you really want to avoid it? Are you scared when an employee – usually one in a distant city, one whom you're not meeting – knows some intimate details about you but he or she is acting exactly in the same way as if he or she knew nothing?

My pragmatic viewpoint is that the only rational reason to be concerned is the possibility that someone will blackmail you or humiliate you or create other kinds of disadvantages for you by using the data that should have remained confidential. If we may be sufficiently confident that such things won't happen, e.g. because they're illegal and someone who would abuse the data would be sufficiently punished to discourage others, we shouldn't be worried about the surveillance too much.

Needless to say, this pragmatic attitude of mine partly boils down to the fact that in my life, I have experienced a sufficient numbers of problems that were caused by real people and people who were geometrically or socially close to me so that I didn't find it helpful or necessary to invent fictitious problems, conspiracy theories, or dragons or to worry about some distant people I have never interacted with.

There is always some risk that something unpleasant will happen to you but these programs also have a virtue that may be much more important: they may actually help to catch many or almost all terrorists and other people who are planning to hurt you or other decent people. And that may be a decisive factor. I am not primarily talking about two or three minor attacks that may be thwarted thanks to similar programs. I am primarily talking about the possible big attacks that may be stopped.

The question whether the government should be trying to protect or otherwise help its citizens in ways that are not transparent at all is very subtle. Again, there are arguments on both sides. The virtue of the transparency is that policies that are found truly unacceptable by most citizens may be identified and stopped – in other words, the feedbacks work and allow the people to improve the system; the vice of the transparency is that it helps the villains to adapt or change their behavior – in other words, there is again a feedback but in these cases, feedbacks are negative things.

Because of the latter reason, I tend to understand the worries of those whose task is to protect the safety of the U.S. citizens. The leak just makes their work harder. The fact may have been leaked simply because someone was honestly stunned by the arguably creepy policy. I can't answer the question whether these people had the right to leak it; I am no lawyer. And the question whether they had the moral right is a complicated one. At any rate, it's understandable that some people sometimes leak such things because they think it's the right thing to do. When policies become sufficiently creepy, you may bet that in a sufficiently large collective of employees that works on them, there will be someone who will leak what is going on. This may be bad for a particular program but it is good, too. It is good because in the long run and when it comes to really big conspiracy theories, you may just dismiss these conspiracy theories.

For example, 9/11 almost certainly couldn't have been an inside job because you would need too many people to cooperate and none of them has leaked it which makes the conspiracy theory unlikely. We don't even have to rely on the belief that no one in the U.S. establishment could have possibly had a sufficient incentive to organize such a monstrous event.

This monitoring is clearly a less ambitious theory than what the truthers believe and it turns out that it is true. The leak will have some consequences and many people may fight to completely abolish similar programs. But I think that such programs are ultimately helpful as well because they help to make the protection of the U.S. citizens more efficient or cheaper or both.

The citizens may think whatever they want but I do think that it would be rational for them to accept a certain layer of surveillance they don't understand as long as there seems to be sufficient evidence that the data obtained in this way aren't being used to harass innocent citizens by the methods mentioned above; and that they're not used selectively against certain groups of citizens in the case that these groups aren't quite innocent but they're doing something that is sufficiently widespread and that would almost certainly remain unknown to the external world if the surveillance didn't exist. (The latter concern – double standards – is a reason why the IRS' harassment of the Tea Party charities may be less creepy but it is more self-evidently immoral.)

It's hard to say whether the mechanisms that already exist – or mechanisms that may be adopted – guarantee that the negative impact of similar policies is minimized and whether there exists a conceptual reason (probably a mechanism) to think that the negative impact will be minimized. People should think about this general framework – how to make sure that the government agencies are working for their interests (because a government that isn't controlled by the people ultimately doesn't have any reason to behave in ways that are optimal for the electorate!) – but I think it's rational for them to leave certain technicalities to the professionals and allow them to maintain a certain opacity because this opacity may work in their interests and for the interests of justice in general.

Trade war: Chinese solar panels vs EU wine

2013-06-06T13:51:00.001+02:00

Business Week and many other news outlets tell us about another worrisome development in a possibly looming trade war between the EU and China (or EU and the rest of the world).

Some EU apparatchiks have decided that China is selling solar panels below cost so they imposed 11.8% tariffs on them – but this fee is meant to grow to 67.9% within two months. Holy cow. China is clearly going to revenge. At this point, they are preparing actions against the European wine. The French who believe that they produce some of the best wines in the world aren't happy but it's their own fault, to a very large extent. And of course that the Chinese investigation of possible subsidies for the European agricultural products should naturally end up with the "guilty" verdict: the European agriculture is subsidized and manipulated with from A to Z. Needless to say, the wines were only picked for symbolic reasons; things would become tougher if China began to target Airbus aircraft, for example.

It's truly concerning to see that among the Chinese communists and the European Union officials, it's the latter who are much more fanatical, unhinged anti-market Mujahideen who don't hesitate to put our continent's and the world economy's health (and perhaps the global peace) at risk whenever they decide to pursue their sick anti-market policies. China says that now, during these trade conflicts, Europe must recognize its decline. It may sound tough but I completely agree with that. If Europe is becoming uncompetitive etc., and there are probably good reasons for that (to a large extent, it's someone's fault, the fault of some very bad policies), it is just completely wrong to try to mask this fact by spitting on others.

The EU "leaders" have already distorted the market conditions so brutally that it may be hard to decide what is actually "normal" and "fair" in the business relationships between Europe and the rest of the world. Incidentally, India and others are still not paying the ransom that the EU imposed upon the foreign airlines operating in Europe and India and probably others are readying reprisals. Not too good.

But let's return to the topic of the tariffs for solar panels.

First, under normal market conditions, there should be no tariffs. If China is helping its products by dumping prices, it's good for the consumers – most of us. Every company – and China is a very large company if you view it in the right way (and some communist policies are its inner issue – every company has the right to organize itself in a way it prefers) – has the right to run campaigns and offer discounts in order to promote its products. It's a completely normal part of the competition. Such a dumping isn't for free; it costs something. The possible benefits include an advantage over competition (especially if the competition can't afford to generate losses or debt, not even temporarily) but this outcome isn't guaranteed. It makes no sense to regulate such things. Dumping and similar things help the consumers to test products they wouldn't otherwise try – and all these things help to make the markets more efficient and consumers more satisfied.

We may find it problematic if a very large "company" such as China, with giant cash reserves, is using dumping prices to prevail in the long run. But whether you like it or not, this extra power does come with the cash reserves. The Chinese have behaved more responsibly in fiscal matters and their greater ability to test the resilience of their competition by dumping prices is one of the prizes you win if you manage to produce savings instead of debt. The converse holds for Europe and its debt-creating policies, of course. So don't whine about it, EU commies and populists: this comparative disadvantage of Europe is your fault.

The tariffs on solar panels are even more insane if you realize that the EU apparatchiks have claimed that "renewable" energy sources were a good thing; they even introduced a huge system of subsidies for these economically unfeasible energy sources themselves. If they were a good thing, they should enthusiastically thank China for sending us solar panels – especially cheap enough solar panels. But quite suddenly, the desire of these officials to irrationally promote excessively expensive "renewable" energy sources is beaten by another hardwired far left-wing instinct, protectionism, and this explosive mixture can't lead to anything good.

China has the unquestionable right to revenge for the disgusting, anti-market harassment launched by the EU officials and start to harass exporters who are sending stuff to China by comparable policies. Europe is the side that started these annoying steps; the EU is the Adolf Hitler of this new war if one is getting started. But do we really want such a thing? Do we want to lose the right to buy cheap foreign products? Do we want our producers to lose the option to export their products to whole and very important parts of the world or to any foreign country?

Do we understand and do the EU apparatchiks understand what this kind of protectionism does to the continental and world economy?

In Europe, the market for many things has been distorted by many illogical and pathological interventions so that sometimes you no longer know what is the actual price of many things. (These things – multiple prices that have nothing to do with each other – are even worse in countries like Argentina, a Latin American visitor recently assured me.) Some imported products are twisted by heavy tariffs. Some products are made cheaper if they agree with some pseudoscientific, ideologically driven criteria of "fighting against the global warming". Others have already been made more expensive with the same excuse, because their production or consumption "contributes to the global warming".

Couldn't we just eliminate all this mess? All this stuff is a road to hell. Every billion dollar that you redirect using these ad hoc regulations is potentially a billion that has been stolen or used for criminal activity according to someone else. You just shouldn't behave that these things can be done routinely.

A trade war may start because of any product but it's no coincidence that products whose prices have been manipulated with – using tariffs, carbon taxes, carbon credits, and similar things – are the most likely products to lead to a trade war because people (and nations) simply can't possibly agree about the right extent to which the prices should be manipulated, subsidized, increased by tariffs and carbon taxes, and so on. And even the same people – in this case the shameful EU apparatchiks – aren't ethical enough to stay consistent in their principles, in their methods to manipulate all these prices, as their sudden opposition to cheap solar panels proves.

Let me tell you once again what is the right extent to which prices or air tickets, solar panels, and hundreds of similar products and services should be manipulated with by tariffs, carbon fees, carbon taxes, carbon credits, and similar fudge factors. The right extent is zero. Everything else is a crime and if the ongoing row will result in a full-fledged trade war with China (or a greater bloc of countries), all the EU apparatchiks and global warming alarmists and protectionists and similar left-wing garbage people deserve a heavy punishment, at least a life in prison. The Old Continent can't afford to let such people escape unpunished.

And that's the memo.

Competing Japanese regions shoot videos to win the ILC

2013-06-05T22:21:00.001+02:00

...a poll...

Japan is clearly getting serious about hosting the International Linear Collider, a planned 250+250 GeV (or later 500+500 GeV) electron-positron collider which could measure properties of the Higgs boson and perhaps other new things much more accurately than the LHC.

As the Symmetry Magazine informs us, two main candidate places in Japan recently released promotional video to defend their candidacies. It looks like the construction is a hot topic although it's expected to begin between 2015 and 2016 and collisions won't start before 2026.

This 4-minute music, choreography-based video featuring some famous actors and cartoons, among other real and virtual artists, is a reason why you should vote for the Sefuri mountains, Kyushu, Southern Japan [Facebook]. Big Ben's music and a short excerpt from Beethoven's fifth symphony – Japan has been crazy about Beethoven since the First World War – can't be absent in the video, either. Can you find it? You must have previously heard Asagohan (Breakfast), an amazing Japanese rendition of the symphony.

I will refer to this place as the "South". The competitors' promotional video couldn't be more different.

The Kitakami mountains in Tohoku, Northeastern Honshu [Facebook], have shot this 21-minute video featuring, among others, Hitoshi Murayama, a top Japanese particle phenomenologist from Berkeley (whom I met a few times).

It's a very serious, 21-minute educational video that isn't trying to be the coolest thing in the world. It's conceivable that only a small portion of the readers will watch the whole film.

I agree with you that it's unwise to choose the place according to some silly promotional videos only. Nevertheless, you're going to vote in a poll, anyway. Based on the films above and no other information:

Sea temperature trend: 1.35 ± 0.15 °C per century

2013-06-05T20:20:00.001+02:00

I made the following easy-to-understand calculation of the warming trend, including an error margin, of the global sea surface temperatures since the late 1970s, as seen by the UAH AMSU satellite dataset.

First, I loaded the file of the monthly data, isolated the third temperature-like column, the global ocean temperature anomaly, and calculated the linear regressions.

It's straightforward to use one simple Mathematica command to compute the slope of the linear regression but the non-trivial addition I made was an estimate of the error margin of the resulting slope. My logic is that for different initial months and final months of the interval, you get different slopes. Then you draw the histogram and the width of this histogram approximately informs you about the error margin of the slope.

So I picked the interval from the $i$-th month of the dataset through the $j$-th month from the end of the dataset and allowed $i,j$ to be integers between one and fifty. One gets 2,500 different slopes from the linear regression. When the month-on-month average slope is multiplied by 1,200 to get the warming per century, those 2,500 slopes are distributed along the following histogram:

One may easily compute the mean value 1.33 °C per century while the root-mean-square width of the curve is 0.12 °C.\[

\ddfrac{T}{t}\sim (1.33\pm 0.12)^\circ {\rm C} / {\rm century}

\] It's also possible to replace the number 50 by another number of months, like 60, and the qualitative conclusions are unchanged.

This really means that the data from the last 33 years – when the observed warming trend was faster than in longer intervals or previous intervals, so we're likely to get an overestimate – the warming trend was just 1.35 °C per century with a relatively small error margin. In particular, we can't exclude that the "right" warming trend is below 1 °C per century. However, we can rather reliably exclude the hypothesis that the centennial trend exceeds 2 °C per century.

If you need some very simple Mathematica code I used:

a = Import["http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt",
"Table"];
aaa = a[[2 ;; -12]][[All, 3]];
more = a[[2 ;; -12]][[All, 5]];
laaa = Length[aaa]

ListLinePlot[more]

trends = {};
For[i = 1, i <= 50, i++,
For[j = 1, j <= 50, j++,
morekus = more[[i ;; -j]];
trend = D[Normal[LinearModelFit[morekus, x, x]], x]*1200;
trends = trends~Join~{trend};
]
]

Histogram[trends]
avtrend = Total[trends]/2500
Sqrt[Total[trends^2 - avtrend^2]/2500]

I chose the sea temperatures because they seem to be less variable in the short run; the nearly white noise apparently contributing to the temperatures has a smaller prefactor. The latest, May 2013 temperature anomaly which sits at –0.01 °C, wasn't incorporated to the calculation yet. It would reduce the trends but just by a very tiny amount.

Needless to say, nothing guarantees that the underlying trend implicitly assumed above to be linear will remain constant in the future. Climatologists are often naively describing the temperatures as a combination of a superfast, nearly white noise (very high frequencies of the randomness) and a superslow, nearly linear and permanent, increase of the temperature (very low frequencies). In reality, there are contributions from many characteristic intermediate timescales, including one or two years or so from El Niño cycles, decades from PDO and AMO and all these things, and probably many other sub-centennial and near-centennial and multi-centennial cycles, some of which are more regular or periodic or predictable than others while others are chaotic.

Even the assumption that the cherry-picked high trend is going to continue doesn't look worrisome in any sense and the underlying trends are safely lower than the lower end point of the IPCC interval.

Note that the IPCC should publish the fifth report, AR5, later in 2013. I am not too curious what will happen but I am still approximately infinitesimally curious how the usual talking points by these mostly dishonest hired guns will change or not change relatively to AR4. ;-)

David Gross on youth, revolutions, conservatives, QM, QFT, QCD, ST, multiverse etc.

2013-06-05T08:35:00.000+02:00

Wired has reprinted an interview of Simons Science News with David Gross:

Nobel Laureate Says Physics Is in Need of a Revolution

Well, I don't think that the title accurately summarizes what Gross said.

He mentioned that he was attracted to physics as a kid, partly by Einstein's and Infeld's book when he was 13. He gives some clues to the interviewer about the meaning of quantum mechanics, fields, quantum fields, asymptotic freedom, and so on.

His adviser Geoffrey Chew has ordered Gross to spark a new revolution by showing that quantum field theory is fundamentally wrong and one needs some revolutionary self-determining theory based on no special "elementary" particles, one satisfying the bootstrap paradigm. Instead, Gross ended up showing that quantum field theory works very well. Thank you.

The younger big shots understood his or their discoveries quickly; the old chaps didn't know quantum field theory well enough so they needed some easily understandable experiments to grasp the idea of the seemingly "unphysical" quarks.

At any rate, this story about an old revolutionary who hires a young gun but the young gun ends up being conservative is presented as something that is rather standard in science. Heisenberg, Dirac, and Bohr were already old chaps who were expecting a new revolution but the Standard Model that ultimately explained the data did nothing of the sort. Instead, it provided us with a conservative accurate reductionist theory based on the well-established concepts and postulates that have passed the tests of time.

You may see that the usual stereotype that the young people are rebels and old people are conservatives doesn't always work in physics – its converse arguably works more often.

Gross interprets string theory as a part and parcel of quantum field theory and in his conventions, it's therefore another continuation of this evolutionary process, not a revolution. In later paragraphs, he makes it clear, however, that the whole portion of quantum field theory that wants to describe quantum gravity well does need string theory and not just the "old things" about quantum field theory.

He says that the landscape of googol-to-the-fifth vacua makes no sense to him. Although I agree with most things he says about the multiverse story, he seems a bit irrational to me when he assaults the very *landscape*. The landscape is just the set of solutions and it is as large as Nature and mathematics decide, not caring whether or not the set and its size "makes sense" to a Gross.

Laymen misinterpret any uncertainty as a "wild guess". In science, uncertainty may be put under control and its existence is actually essential for a proper scientific understanding of anything. In the absence of experiments directly settling questions, we must rely on other scientific methods and we may arguably get very far with them. Philosophy isn't one of them; if a philosopher can offer musings that contribute to physics, he or she is actually doing physics.

The interview ends by not so controversial statements that science describes objective laws and patterns because even the human mind is a physical object. Maybe the author of the question wanted Gross to talk about the interpretations of quantum mechanics but he didn't understand it that way.

Asymmetric fates of rivers of Pilsen

2013-06-04T15:41:00.001+02:00

There were only two rivers, Euphrates and Tigris, in a defunct multicultural city surrounding Saddam Hussein's summer palace 50 miles South of Baghdad but the number "two" was apparently sufficient to earn a famous song by the German band Boney M.

Rivers of Babylon. The description "German band" is a bit subtle if not amusing not only because of the racial laws of the 1930s but also because of the simple fact that only the producer was German while the singers were Britons from three Caribbean islands.

The rivers of Pilsen, my hometown, haven't generated any famous song yet despite the fact that Pilsen was cleverly established in 1295 near the confluence of a whopping number of four rivers. (A confluence of five rivers, an even larger number, was outsourced somewhere to India.)

I don't want to make your life harder by forcing you to pronounce four Czech names of the rivers (Mže, Radbuza, Úhlava, Úslava) which English speakers often consider a hard job. And even the German names may be hard and incomplete (only their name "Angel" for Úhlava is acceptable in English) so let me call the rivers Drizzle, Lovefaggot, Byhead, and Byfame which are lumoesque ad hoc translations of the Czech names that were created for the convenience of readers like you.

All these four rivers flow for about 100 kilometers before they reach the confluences in Pilsen. Drizzle, Lovefaggot, Byhead, and Byfame arrive from West, Southwest, South, and Southeast, respectively. They merge to the Berounka River (named after the town of Beroun near Prague) which continues to Northeast where it contributes to the Moldau (Vltava) river in Prague, also after 100 kilometers or so. All the four springs are located in Bohemia except for Drizzle which originates in Germany but just a mile behind the border.

In the recent year or so, I reorganized my understanding of the local geography. I would previously use man-made structures, usually at elevated places, as the main points of reference. These days, I partly think about the locations relatively to very different benchmarks, the one-dimensional rivers, whose altitude is naturally rather low.

One of the great realizations ;-) that have led to this paradigm shift was the idea that if you ride your bike near a river, you don't have to pedal uphill too much – because the rivers themselves don't like to do such things due to the bureaucratic constraints imposed upon them by the force of gravity (it sounds like a triviality but I needed experiments to be forced to realize or "discover" such a thing). And because most suburbs and villages in the Greater Pilsen sit at one of the rivers, one gets quite a nice grid that may be exploited to estimate the distances and quantify the coordinates.

In recent days, the Czech Republic and parts of Austria and Bavaria have experienced some mild inundations – which you've probably seen on your TV screen under the trademark "Armageddon" (even though the very throughflow is just 3/5 of what it was e.g. in August 2002). Four days ago, they would begin on the Gossip River (Czech: Klabava), the first non-Pilsner river that will become the fifth Pilsner (Berounka) tributary sometime in the future and where I spent lots of time during trips in April and May. Today in the morning, the weather turned partly sunny so I simply couldn't resist and had to inspect about 30 places near rivers in Pilsen.

Some of the changes made me excited; others made me impressed by the absence of any effect.

By the latter, I mean the Drizzle River coming from the West. It doesn't seem flooded at all. This is particularly ironic because those of us who have studied the industrial and agricultural history of the Pilsner region must know that the Drizzle River has been by far the most flooding one. Large areas near the Drizzle used to be inundated quite often which may look like an annoyance but these events were actually helping to improve the quality of the soil. The village of Křimice, now an administrative part of Pilsen, is a major example of a place that became famous for some of its agricultural products – cabbage, fruits, and so on. Byfame is often considered the least important one among the rivers of Pilsen and you may also see that the towns and villages on Byfame had to rely on some industrial (and not agricultural) production for more than a century.

(Oops, only in the evening I realized that the calmness of the Drizzle River has a simple reason: they decided to accumulate all the water – and there probably has been excess precipitation above Drizzle as well – in the Pealegumes (Hracholusky) Dam.)

Lovefaggot near the American Avenue is approaching the confluence with Drizzle. In the middle of the background: the Western Bohemian museum and the (green) Pilsen tower, i.e. the St Bartholomew Cathedral. The changing names of the American Avenue, the largest commercial street in Pilsen, represent a nearly self-satirizing testimony to the frequent changes of the political arrangement and the Czech opportunism. The avenue began as the Imperial Avenue in the 19th century to celebrate the Austrian Empire. In the early 20th century, it would be called the Jungmann Avenue to celebrate a 100-year-old patriot and a leader of the national revival. It would quickly be renamed as the Joseph I Avenue after a (then) 200-year-old emperor. After Czechoslovakia was created in 1918, it would be renamed the Wilson Avenue for 20 years to thank Woodrow Wilson for his contributions to the birth of Czechoslovakia. When the Nazis took over, the avenue would become the Charles IV Avenue, after a non-problematic and beloved 14th century Czech king and Holy Roman Emperor. In 1943, the Nazis optimistically renamed it as the Victorious Avenue but after the true victory in 1945, it became the Stalin Avenue. In the early 1960s, the Soviet leader became a bit unpopular so it was renamed the Moscow Avenue, before it turned the General Ludvík Svoboda Avenue after a war hero and a moderate communist president. In 1970, it was again the Moscow Avenue. In 1991, two years after the fall of communism, we had the American Avenue, with a short-lived confusion because some people wanted to call it the Prešov Avenue after a rather small East Slovak town (but a smaller street near the city center was ultimately named after Prešov). ;-) Just try to count the number of names! I must say that we have lived in the age of an unusual stability since the early 1990s.

It's helpful to know that Lovefaggot devours the Byhead river in South Pilsen (the Slovany=Slavs suburb) before it (Lovefaggot) reaches the most important confluence in Pilsen which is just 100 meters from the stadium of the Victoria Pilsen soccer team, the fresh Czech champion (the buildings in the right half of the map belong to the brewery). At this point, Lovefaggot joins Drizzle. Drizzle is the larger tributary so by the usual conventions, the resulting river should be called Drizzle. In fact, some Pilsner historians wanted to ban the name "Berounka" for the river between Pilsen and Prague and rename it to Drizzle again, while quoting some vague historical documents indicating that someone was calling it the Drizzle River even in places between Pilsen and Prague. They would even claim that Berounka was a nearly communist construct because the name only began to be used in the 17th century. ;-) Needless to say, their efforts to rename 100 km of a well-known river used by canoeists etc. had no chance to succeed.

When the river is already called Berounka – the major tributary of the Moldau River in Prague – it is going to devour the Byfame River in the Oakforest (Czech: Doubravka) suburb where I currently live. 10 km later, out of Pilsen, Berounka also devours the Gossip River.

So the most impressive negative surprise was the complete lack of a flood on the traditional flooding river of Pilsen, the Drizzle River. In fact, the confluence of Drizzle and Lovefaggot offered an unusually asymmetric perspective. Lovefaggot was boasting lots of excess water from the South. The water level was elevated by more than a meter and weirs became nearly invisible. The speed of the water may have been 3 meters per second and it was about 5 meters per second when I saw it yesterday.

On the contrary, Drizzle was nearly static near the confluence. I believe it was moving at 10 centimeters per second – and slower than normally because I believe that the normal speed is half a meter per second or so. How is it possible? Well, the confluence guarantees that the water level in Drizzle is elevated as well, due to the extra water in Lovefaggot, which increases the average cross section of Drizzle. Because the throughflow (volume of water per second) isn't really changed, a greater cross section of Drizzle translates to a much lower speed.

However, as soon as the Berounka River is created at this confluence, one may observe something I was already impressed by as a kid during the floods in the early 1980s - the Super Berounka River. Just imagine that most of the fields in the middle of this map became a part of the Berounka River.

At the end of the field, there is a bridge named after the nearby butchery which was closed due to some stability concerns; I knew it from the media. I also knew that the St George Church and Cemetery (center, just meters from the Berounka-Byfame confluence) became an island. But it isn't just an island in a peaceful sea. The water is flowing several meters per second on both sides.

I was sort of surprised that this pedestrian bridge at the center of the map was "naturally closed": about 50 meters of a vigorous Berounka River prevents pedestrians and cyclists from crossing this footbridge.

These are some exciting experiences just from several – or a dozen – of miles on four rivers. The inundations have affected hundreds if not a thousand of kilometers on dozens of rivers or so which means that what I have seen should be multiplied by 100 or so to get a realistic idea about the "geographic changes" that the inundations have brought us.

Let me mention that I described some factoids about the inundations in the box at the top of an article I wrote yesterday. The precipitation is pretty much over and places like Pilsen are already well after the peak; even Prague peaked around 6 am today. The excess water is moving to the lower portions of major rivers, especially Elbe (which has the Moldau as the most important tributary) and Danube. I don't expect any additional catastrophes. The damages are just a few billion crowns - multiples of $50 million. Six casualties – not necessarily people who were behaving safely. Lots of black humor about sharks and swimming races in the subway stations, a drunk president Zeman rafting near the Sri Chinmoy's statue to save the country, and many other things.

Mountain climbing in Antarctica etc.

Tonight, I attended a presentation by Mr Rudolf Švaříček (51), an adventurer, mountaineer, writer and publisher of travelogues, and owner of a travel agency called Livingstone that sells vacations in highly exotic destinations. It was an evening similar to one with Jakub Vágner more than a year ago.

He was a member of a small group – I didn't quite catch who did it and who didn't – of men who managed to walk from a sea shelf right to the highest peak of the Antarctica, Vinson Massif. (He has also been to most other countries in the world, especially those with high mountains.) Lots of amazing stories where they almost sacrificed their lives, extreme frostbite, lost toes, teeth, and so on.

I am not really following the world of the best alpinists and mountaineers so I don't know the names well. But of course I knew some of the people whom Mr Švaříček is really close to – the legendary old Czech traveler Mr Zikmund (his companion Mr Hanzelka died a decade ago), some top Czech mountaineers I don't remember, Dalai Lama who opened some exhibitions by Mr Švaříček, Karel Schwarzenberg, the unsuccessful #2 presidential candidate from the first elections a few months ago, and especially Dr Pavel Bém, the ex-mayor of Prague.

You may want to hear your humble correspondent as he boasts that he answered the highest number of quiz questions during the talk although it's not really my field. ;-) First, we were asked about the primacies of Antarctica. It's the coldest one. He wanted to hear it was the driest one, but I also added it was the most Southern one, and had to get some mysterious holy stone with some sacred scripture of some African tribes or whatever it is.

More seriously, we were asked how many Czechs have climbed Mount Everest from the Southern side. He previously mentioned many names of Czechs to confuse the audience. So for a minute, I was listening as the 100 folks in the audience were saying or screaming all kinds of integers you may think of. Six. Ten. Seventeen. Three. Eleven. Two. Twenty. I was thinking: Ladies and Gentlemen, please keep on talking all your gibberish, you have no chance. When the noise subsided a little bit, I loudly and authoritatively said: ONE. :-) So I won a plastic bag of Konyagi, a Tanzanian alcoholic beverage that Mr Švaříček was holding in his hands on a picture from the Antarctica's highest mountain (at least he claimed it was the same one) in order for the beverage to save his life whenever needed.

Of course, this ONE man is Dr Pavel Bém himself, the ex-mayor of Prague (now he is the ex-ex-mayor because his successor was made resigned a week ago, too, after a coalition in Prague broke down). In fact, it's plausible that this answer may be found somewhere on this blog. When he asked how many Czech people have conquered both Mt Everest and K2, I was listening to a very similar minute filled with random numbers. But I was already feeling painful to shout the right answer which is again ONE, of course, namely Pavel Bém again.

There was a different quiz how to find "six other months" in a calendar that apparently only shows 6 months out of 12. Ten people on the left side from me have been playing with the calendar for about 5 minutes, nearly destroying it. Of course I knew what to do. You may open it on both sides, including the edge where it seems to be bound. It's hard to say why one knows most of these things. I had to see a wallet using the same trick some decades ago or whatever it was. I am sure that some readers know what mechanism of the magic (flip) wallet I am talking about.

But back to more important things. The adventures that these people undergo are amazing and relatively speaking, I would say that these things aren't really too publicized, either. Although it's not exactly my cup of tea, I think that these extraordinary achievements or examples of courage don't get enough attention from the mainstream media and other resources most directly communicating with the public. It's a pity.

Mr Švaříček also talked about the importance of friendship in these trips and his love for the native tribes who can sometimes achieve more amazing things than the white tourists, without all the fanfare. We were also told that a mafia of gangster millionaires and mountaineers who de facto own the Antarctica and want to have a monopoly over flights going there was working hard to make the tourist achievement – walking from the sea to the highest peak – impossible by fudging the schedule of the flights. They failed, anyway.

LARES: a discoball for eurocents that supersedes Gravity Probe B

2013-06-03T21:22:00.000+02:00

Fred Singer was intrigued by a new object shot by ESA to outer space, a shiny disco ball that verifies Einstein's general relativity.

See the following preprint and other sources:

LARES succesfully launched in orbit: satellite and mission description by Antonio Paolozzi, Ignazio Ciufolini (arXiv)

The Extraordinary “Disco Ball” Now Orbiting Earth (Physics arXiv Blog)

Wikipedia, A LARES website (ASI, Italy), Lares-mission.COM

It's literally a disco ball, a completely passive object reflecting LASER lights sent from the Earth to its 92 retroreflectors, an 850-pound ~~gorilla~~ wolfram alloy ball that may be exploited to accurately measure the position and orientation of the disco ball and verify the Lense-Thirring effect i.e. rotational frame-dragging predicted by Einstein's theory of gravity.

Recall that Gravity Probe B was very expensive and it was a disappointment, too. If LARES is going to measure these things and perhaps much more accurately, and for a tiny fraction of the price of Gravity Probe B, it will be another piece of evidence that substantial technological improvements are often possible and may allow us to measure things that were once thought to be inaccessible.

Well, the success of LARES will be a bit embarrassing for the people around the design of Gravity Probe B, too, including George Pugh (MIT) and Kip Thorne (Caltech), but their contributions may have been necessary for the progress, too. Things aren't usually invented in the optimal and maximally cheap form at the very beginning.

Because we talk about clever gadgets, let me also mention that the Bell Labs developed a lensless camera (preprint).

Most questions are no good

2013-06-03T17:45:00.003+02:00

Off-topic, floods in Central Europe:

It all started in the Pilsner Region (3 days ago, the Klabava River I know from many recent trips was the flood superstar) but the elevated water has spread to Czechia and Austria and beyond as the excess water molecules are rolling down to lower altitudes.

Note that Czechia's Western and Northern borders are composed of mountains. Because our country is in the very center of Europe, we sit at the intersection of major river basins: North Sea (Elbe mostly via Moldau, green), Baltic Sea (Odra, yellow), Black Sea (Danube via Morava River, blue). The rain should stop tonight or tomorrow and the excess water should disappear from the higher altitudes and move to lower Elbe and Danube sometime tomorrow.

Eastern spiritual nut Sri Chinmoy's statue in a not-so-waterproof central Prague museum became a helpful benchmark to measure the water level while his prayer-like gesture involving his hands captures some of the atmosphere.

There's lots of water at places where we're not used to water, closed schools, a part of the Prague subway near the historical city center, flooded museum at the traditionally flooded "Kampa" suburb of central Prague etc. Six casualties in Czechia (including a canoeist in Greater Pilsen, a 69-year-old man who got sucked by a pipe of the sewerage system, and an energy utility employee: I know, this is not supposed to be a comedy show but I do think it would be wrong to hide that not all the casualties were behaving safely and shared no responsibility for their end) so far.

Look at this place in Pilsen I inspected 30 minutes ago. Now, the pedestrian underpass may only be followed if you swim in the dirty water which moves over 5 meters per second and goes from the wall on the left side to the underpass on the right side, up to the height reached right beneath the rim of the bridge. My guess is that the water level is just 1 meter higher than usually. However, an old St George church (it was on that place since 992 AD) one mile from my home was surrounded by water and placed on a temporary island. ;-)

Elsewhere, the situation has greater – mostly logistical and economic – consequences. Everyone who has flood-sensitive assets or responsibilities is surely forced at least to think (and sometimes act) about all the usual flood-related topics. However, I would still say that the floods are far from being comparable to the August 2002 floods [videos from Pilsen] I remember rather well.

See also a gallery of 100+ Czech fresh flood pictures. See 200+ more pictures. Almost 200 pictures from Greater Pilsen. Prague – with the Moldau River above 3,000 cubic meters per second (well below 5,000+ in 2002) – is experiencing a "20-year flood" with contributions both from Berounka (the river we send here from Pilsen: Berounka is the union of 4 tributaries, the rivers of Pilsen: Mže/Mies, Radbuza/Radbusa, Úhlava/Angel, Úslava) as well as from the Moldau Cascade of Dams that had to be released a bit; North Bohemian City of Ústí Upon Elbe expects a "100-year flood". See a video of North of Prague.

In Prague, the water will peak sometime on Tuesday (tomorrow) around 6 am.

There has been quite some discussion on TRF and elsewhere whether the question

What is the feeling between the two magnets? There's something there.

that an interviewer asked Richard Feynman during the Fun To Imagine program was a good or well-defined one. I am in the camp of the "resounding No" and in this text, I want to enumerate a few dozens of things that are often (or usually) wrong with the questions that are being addressed to scientists or that are even marketed as building blocks of the scientific process. Some of the observations apply outside science, too.

I believe that it's a part of the intellectually degenerated "postmodern" education promoting the humanities and the political correctness that people are led to believe (i.e. they are being brainwashed by the meme) that it's never painful to ask a question. In fact, we often hear that a question is always important, one should always be applauded if he asks a question, there are no bad questions, and it's always the fault of the person who is answering the question if a question leads to no constructive exchange.

Well, I beg to differ. Every single statement in the list above is wrong; questions may be bad and a large percentage of questions actually are bad; if questions are treated as contributions to the research, it's necessary to judge their quality just like we quantify the validity of hypotheses and the value of the answers; asking a stupid question may be a sign that someone hasn't learned something important that she should have already learned; quite generally, if we ask a question to someone, we should have some respect for his or her time and work a little bit to increase the odds that the question-and-answer exchange will lead to something useful (for us or perhaps also for others).

This culture of worshiping the questions for their own sake leads to the habit of ignoring the answers, ignoring the truth, and reducing the conversations and question answering to mindless exercises in which someone replies by a statement to a question and no one really cares what the reply is. But there are many other things that should be said about this topic. Let me start to enumerate the frequent flaws of questions.

Here is a partial list. Questions are often ill-defined, worthless, or demagogic for the following overlapping reasons, among others:

The words used in the question are ill-defined.
The words used in the question are ambiguous.
There are no settled rigorous enough definitions of the words or phrases in the question although the answer depends on them; only the formulation in terms of rigorous enough mathematical concepts would make the question meaningful.
The question wants to reduce one of the most fundamental concepts to even more fundamental ones, not realizing that the efforts are counterproductive verbal exercises if we're not guaranteed that this process stops at some point.
The question implicitly makes some invalid assumptions about the insights that are already known.
The question implicitly makes some probably invalid assumptions about the format of a future explanation of something.
The axiomatic system i.e. the set of possible true propositions that may be used in an answer is completely unclear – the context or target audience for the answer isn't specified. Even the author of the question has no idea how a satisfactory answer could look like; he must know that the question won't lead to anything sensible.
The question doesn't have a sensible level of difficulty that could produce a meaningful answer: it's either too primitive (something that the author of the question should have known) or too ambitious and it's asking about a point that shouldn't need an explanation at all or, on the contrary, a topic that needs hundreds of pages to be properly covered (which seems to expose the disrespectful assumption that the person who is answering may be "demanded" to spend much more time than the author of the question).
The question isn't meant to be a real question – a sentence designed to find some information – but rather as a rhetorical question to spread a certain way of thinking or emotion, usually a misconception.
The question is just an attempt of its author to pretend that he or she is smart but he or she isn't really interested in the answer.

Quite generally, the idea that the "author of the question is allowed to do everything" while the "person who answers only has duties and should suffer" is a part of the political correctness and mediocracy of the postmodern age. The authors of the questions are "us", the losers who know nothing and who have no duties and responsibilities and who have the right to demand anything, everything, and any entitlement they can think of; the people who are expected to answer are "they", the evil powerful people, the old white men or the Jews or the Big Oil interests (fascism, environmentalism, or feminism may use different words but in all cases, it's still the hated "they" and the logic behind all these pernicious ideologies is structurally the same), those who should be tortured.

Of course that the world doesn't work like that at the end (those hated "they" are either eliminated or they remain in the positions of power and become able to control what questions are allowed to be asked by "us" etc.) and it couldn't work like that but the totally distorted view that it "should" work like that is a testimony of the insanity of the left-wing, postmodern populist ideologues that have contaminated the intellectual atmosphere in the Western society in the recent 80 or 50 years or so (80 if I count the fascists).

The list above is in no way complete. Indeed, questions suffer from many diseases. It shouldn't be shocking that most questions that are being asked are garbage; if we live in a culture without any "natural selection" for questions – if the authors of questions are never "punished", regardless of the questions' very bad quality – it's sort of inevitable that bad, worthless, sick, stupid, and demagogic questions are guaranteed to "flourish" and contaminate the intellectual landscape. In principle, every single illness of a question in the list above could be understood as a lethal one – but you find many people whose questions suffer from every single disease in the list.

A few extra words about the illnesses and some examples follow.

Physics vs philosophy: ill-defined words

First, "ill-defined words". This is a frequent problem with the ancient philosophers' and armchair philosophers' questions and their approach to questions. This problem is really the primary reason why physics and philosophy had to divorce. Philosophy was no good because it was stuck in the "research" of tons of meaningless questions that could perhaps satisfy the rules of syntax but whose content was vacuous.

For example, philosophers may be obsessed with repeating enchantments involving the "free will", "background independence", "reality", and so on, and so on, and they ask whether these concepts are true or whether they exist. It depends on what these words actually represent. And there's no reason why Nature should associate a well-defined meaning with any sequence of words or letters such as these ones and thousands of others.

An essential fact for a scientist to realize is that there's no reason why a syntactically or grammatically legitimate sentence should be valuable or should deserve a well-defined answer or truth value (if it is a Yes/No answer). The language is a tool by which humans (or others) exchange some information. But if one uses it incorrectly, no information is being communicated, the sentences are meaningless, and it makes no sense to spend hours by trying to find answers. Some hard work and "assurances" are needed for a language or a more general framework of communication to be useful. If these conditions aren't met, the sentences won't be useful – they won't be useful for practical lives of the people; but they will be useless in the plan to learn the truth about Nature, too.

Philosophers – including philosophers who pretend to be interested in science but they are still just philosophers because of the unscientific character of their thinking – often misunderstand these basic facts. So they keep on solving questions that are ill-defined because the very words and phrases used in these questions have nothing to do with the fundamental concepts that the state-of-the-art scientific description of the given topics uses. They implicitly use an obsolete "theory" to talk about various things in the Universe.

Do we have a "free will"? I don't know what the question means. The fact that the Universe obeys some laws of physics (even though their character is probabilistic) could be interpreted as the answer that any "free will" is an illusion. But one may define the free will more specifically as some properties of spacetime regions and their ability to produce their own data and in quantum mechanics, the "free will theorem" may be proven to argue that these spacetime regions really "invent the answers" to the quantum mechanical measurements themselves. Clearly, the amount of sophistication in the "free will theorem" goes well beyond the naive mode of thinking that a typical author of the question "Do we have a free will" have in mind. So if you offer the free will theorem as an answer to a typical person's question about the free will, it's destined to be an example of throwing the pearls to the swines.

Philosophy – in the modern sense, i.e. the discipline of the humanities that has already lost its beef (natural sciences) – is largely based on the mindless worshiping of some human "authorities".

Sometimes their patently wrong answers are being preserved many centuries after their invalidity has been demonstrated; the very obsession with Aristotle's teachings has made a greater disservice to the emerging science, one that decelerated the birth of science more dramatically than the obsession with the life story of Jesus Christ. But even when the philosophers only worship the questions as something they should spend years of thinking with, it's often worthless questions. They don't want to admit that e.g. most of the would-be deep things that Aristotle said and asked about Nature were just naive stupidities at the level of an average educated teenager in 2013, artifacts of the stunning primitiveness of the description of Nature that was available when he was alive. This very simple observation is treated by some people – the "philosophers" – as a heresy you shouldn't even consider so you can't be surprised that such people haven't really made any progress in their understanding of Nature during the last 2,000 years. It's their very own, fundamental decision not to make any substantial progress. At least, the value of the questions asked centuries or millennia ago can't be questioned. In this respect, the philosophers are as dogmatic and incompatible with the process of learning as deeply, fundamentalistically religious folks.

The second item in the list above talks about ambiguous words. The situation is even worse when one meaning of the word may meaningfully appear in a question but the question is actually asking about another meaning of the word. It's sometimes very important for the well-definedness of the answer to decide which exact meaning of a word is meant in the question. Such a fine dependence of the answer on the detailed adjustments of the question automatically makes the question "less rigid" and therefore "less important" (it's obviously not the only aspect that can make a question less important, however). In some cases, only a rigorous enough reformulation in terms of nearly mathematically, rigorously defined concepts becomes the only way to make the question meaningful. Needless to say, the "philosophers" and other humanities-worshiping invaders into science often hate mathematics and they just don't like the self-evident fact that the language of mathematics is the only language that can turn many vague sequences of words into well-defined questions.

Some foundations or true propositions are always needed

Several items in the list above are talking about this widespread problem. When we want to understand a certain topic, e.g. the reason behind a phenomenon such as magnets' attractions (and it doesn't matter at all whether we start the question by the words "why", "how", or "what is the feeling"), we should always have some knowledge i.e. some propositions that we consider true and that the person who is answering the question is allowed to assume.

If we don't have any propositions that we accept to be true or concepts that can be used without further questioning, it simply means that we have no knowledge and there can't possibly exist a legitimate way to answer our question, whatever the question is! This utterly simple and logically self-evident point is clearly misunderstood or underestimated by many authors of various "why" questions who seem to believe that one may answer questions so that the answer depends on no assumptions whatsoever. If we respect the validity of no facts, we may always ask "why" after any sentence that the person who is answering adds. We may "question" every statement he makes, whatever the statement is. In such a situation, it is totally clear that such a conversation can't possibly lead to any meaningful outcome. We're caught in an infinite loop (a smart enough girl from the kindergarten should be able to see the proof why the loop is infinite!) and we're clearly wasting our time (and sometimes also the time of another person who is not as stupid as we are and who really didn't want to waste his time!).

So one must always have some axiomatic system, a collection of propositions that we can verify to be true or a whole methodology (e.g. one based on observations or rigorous mathematical derivations) that allows us to verify the validity or invalidity of whole classes of propositions we haven't previously encountered. We may often be more certain or less certain about various propositions in which case the confidence level (subjective probability of a sort) between 0 and 1 replaces the binary truth value that may only be 0 or 1. But there must be something like statements with a truth value or with a confidence level, otherwise it makes no sense to discuss the validity of any other statements or explanations. More strongly, we should also have some idea about which statements are more fundamental as components of an explanation than others; this idea is needed to decide whether some answers and explanations are actually representing progress in our understanding why certain things are the way they are.

Needless to say, the humanities-oriented education encourages people to know no hard facts like that (they prefer the superficial form, they prefer to train folks to master the tools to pretend that they're smart even if they are completely uneducated imbeciles) – and, which is even worse, to be proud about this complete ignorance of theirs. Their brains' being an example of the vacuum still doesn't prevent them from writing their "opinions" about many things. That's, for example, why most science journalists are writing about topics they don't know anything about, except for two or three (usually invalid) slogans and clichés.

When the situation of the author of the question isn't that hopeless, she or he has some axiomatic system to build upon. But even in that case, it should be made sufficiently clear what the system is. The guy who asked about the magnets didn't specify what he knew if he knew something at all. So of course that the appropriate explanation of magnets is different when the target audience are typical 6-year-old kids, curious 15-year-old teenagers, college students, graduate students, or peers of the theoretical physics Nobel prize winners.

This dependence of the appropriate explanation on the target audience is something that is hard to swallow for many people, too. They would love universal answers. But only the most advanced answer may be really superior, in comparison with the more primitive and less accurate ones. But a vast percentage of the people simply doesn't have the background to understand these most advanced and accurate explanations.

In this context, I must also defend the schools. At basic schools or high schools – and perhaps in the colleges – kids are taught some simplified answers to questions that use a somewhat more primitive system (e.g. classical mechanics with forces or something even simpler), oversimplified methods to reason, approximate and obsolete models of the physical world, and not the most accurate mathematical tools to calculate the answers. But this is really inevitable. If a 6-year-old girl can't understand a more accurate explanation (e.g. because she hasn't mastered quantum field theory or string theory yet), it would simply be a waste of time to provide her with an advanced (e.g. quantum-field-theory-based) explanation of a certain effect. It would be a case of torturing kids if she had to memorize an explanation based on M-theory. This is true not only for 6-year-old girls but also for 50-year-old men who just don't know certain prerequisites (and for everyone else, too). The very fact that their background knowledge has some limitations – i.e. that they're qualitatively analogous to the 6-year-old girls – is something incompatible with the pride of many adults (and teenagers). But their pride can't change anything about the fact that they may only understand certain answers and explanations that are optimized for the background they have already mastered.

The interviewer asking about the magnets hasn't explained what his background was. His talking about "feelings" indicated that he knew nothing about physics at all, not even the things he should have learned at the basic school. In such a situation, it's hard to answer a question that sounds like if he wanted to understand the deepest reasons behind magnetism. One simply can't understand the deepest answers about the Universe with the shallowest possible knowledge and the most modest skills he can possibly have. These are incompatible things. The interviewer's attempt to suggest that he's thirsty for the deepest explanations even though his knowledge seems to be the shallowest is a hint that he's one of the pompous fools that Feynman couldn't stand – and I can't stand them, either.

There are no feelings between magnets. Magnets are manifestations of the magnetic field constructed from the aligned magnetic fields of the electrons' spins (in the case of the bar magnets i.e. ferromagnets; diamagnets, paramagnets, and electromagnets would require three other explanations) and the magnetic field (which appears in all these situations) is one of the most fundamental things that exist in Nature. One may reduce the electromagnetic field to things that are "somewhat more fundamental" than just the postulated electromagnetic field but one must first learn physics to understand the electroweak theory, the grand unified theory, and/or string theory. Except for the string theory case, one "reduces" the electromagnetic field to things that are generalizations of the electromagnetic field, anyway, so one doesn't really discover any genuine simplification.

But if one doesn't know the tools to follow the electroweak theory or the harder things, he should just accept that the electromagnetic field is one of the most fundamental things in the Universe and it is, on the contrary, all the everyday processes (like all of chemistry, biology, electrical engineering, or the pressure exerted by a finger, among others) that should be explained in terms of electromagnetism, not the other way around! Physics isn't trying to reduce the magnetic forces to "feelings"; on the contrary, physics and biology are reducing feelings to electromagnetic forces. And I think that this fundamental importance of electromagnetism is such a basic, game-changing part of the natural science that a person who doesn't know that electromagnetism is this important and "unquestionable pillar of science" simply failed to learn physics at the basic school level. We're not talking about any state-of-the-art physics research. We're not even talking about the college-level physics. We're talking about the question whether one listened to and understood some basic physical facts that were said to him when he was 10 years old – and for the interviewer, the answer is almost certainly No. That's why it's immensely annoying if such a child who was left behind is trying to look smart by asking similar would-be deep questions about the "feelings causing magnetism".

Demagogy, rhetorical questions that should be real questions, hidden wrong assumptions

Several items in my list are dedicated to the questions which aren't asked in order to find any useful information at all. Some of them may be designed for the author of the question to look smart (or deep) and/or curious even though he self-evidently is neither smart (or deep) nor curious.

Other questions are designed to promote invalid assumptions about physics that is already known. For example, when Lee Smolin asks "How to get a background-independent theory of quantum gravity", he wants to promote his lies about string-theoretical dynamics' not being background-independent. He has been repeatedly caught as admitting that he realizes why these propositions are lies (David Gross gave a detailed monologue about this fact to other folks at a conference) but he still finds it useful if the brainwashed laymen who are actually ready to pay for Smolin's garbage books – the children who were left behind – are being indoctrinated in this way. So his questions aren't really questions. They are references to some lies he has made at other places. These would-be questions are encouraging the brainwashed readers and listeners to repeat the lies they have been exposed to in their heads. It's a part of his Goebbelsian effort to sustain the lies that are convenient for him.

He is a dishonest jerk and a demagogue and of course that most demagogues are using various loaded questions as very effective weapons in their propaganda wars. A whole category of these "sick questions" are rhetorical questions that shouldn't be rhetorical at all. Many people often ask a question and they don't really expect an answer – even though there actually often exists a very solid, satisfying answer to the question (in this sense, the situation is the opposite one than the situations described in the early portions of this essay). They just mean their questions as attacks.

There are lots of diseases that questions may suffer from and they often do and I could talk for hundreds of hours. But I want to emphasize the basic point: if we want to count questions as intellectual contributions, we must care about their quality, too. As soon as we start to think about questions a bit less uncritically and to compare their quality, we're already on the right way to avoid some of the traps (or all of them).

Richard Feynman: Fun To Imagine

2013-06-02T09:11:00.002+02:00

You must have seen many excerpts from the following video featuring Richard Feynman:

But maybe you have never watched the whole 66-minute-long video. Here it's waiting for you.

He covers lots of things – need for imagination in physics; heat is wiggling; surface tension is the attempts of molecules to get in...

In a similar way, he explains using the atomic language why gases cool down when they expand. And thousands of other fun things...

Various atoms like each other to various degrees. Wood and oxygen. They get caught and create lots of jiggling which is spread elsewhere and what you get a catastrophe. The catastrophe is called fire. ;-)

Where the did carbon get there from? It came from the air. The wood is from the air: it grew by absorbing carbon dioxide. Just a little bit from the ground. These anthromorphic stories about the life of the atoms sound funny.

He also traces the energy – it ultimate comes from the Sun. Where did the Sun find the jiggling (energy)? He has to stop somewhere...

How do rubber bands work? There are chains of molecules but other molecules are jiggling and hitting the chains, trying to shorten them. It only works when the rubber is warm – heat is necessary. Rubber bands' temperature goes up when you stretch them and vice versa. The jiggling is inside everything.

Around 14:40, the scene about "what the magnets feel" starts. You must have already seen this exchange. An irritated Feynman repeats the claim of the author of the question that it's an excellent question but makes it very clear that the question was utterly idiotic, too. When we ask "why", we must have some facts that we're allowed to use as more fundamental facts, parts of the answer. Magnetism is more fundamental than the macroscopic events we know from the everyday life.

At 22:07, we switch to a dentist and a water dam. Turning wheels in the dam make all the wheels in the city turn. It's all about iron and copper, a natural thing. Again, he points out that there are long-range forces that are more fundamental than the "direct touch" forces we know. Gravity is much weaker; but it may matter when the electric forces etc. get neutralized.

31:40, fraternity at MIT gives questions like: Why you get left-right but not upside-down reflected in the mirror? ;-) A fellow Junior Fellow in the Society of Fellows (humanities) was impressed by this question and didn't want to believe that I could solve such a problem. ;-) The actual mirror only reflects the front-rear direction. We just psychologically imagine that the image is rotated around the horizontal axis – this rotation is a symmetry unbroken by the gravitational field – which makes the image left-right reflected.

34:50, what keeps the train on the tracks? The planes of contact are tilted, regulating the direction back if the train is destabilized much like the differential – something that the trains don't need.

37:20, seeing things. A not too pretty woman sitting in the swimming pool allows one to watch the waves instead. Sensitive spots in the eye. Mess of waves in the space (electromagnetic fields with all the frequency modes) and complicated mechanisms in the eyes and radios. As a kid, I was also stunned when I realized the idea that all the information about all the radio and TV stations is flying around me in the room at the same moment.

At 43:20, he talks about scales. Big numbers. You scale yourself to imagine them. Why Earth is round. Nuclear fuel. Neutron star matter – balancing gravity and pressure. Pulsars – they're the same thing. Immense densities, confirmation of predictions. Black holes.

54:30, ordinary people like Feynman can master these things. There are no miracle people. With some investment of time, he becomes a scientist. A bit too idealistic. 55:20, his research is a nutty mixture of equations, ideas, and vague pictures of equations. In every man's head, the imagery is probably very different from others. Translation engines work hard. He thinks so because different people solve problems differently. Feynman couldn't do counting multitasking; someone else uses an optical system for counting.

1:00:55, I have already linked to this many times. We're used to understand very different phenomena than the fundamental ones. Quantum mechanics is wonderfully different than the macroscopic world. People who try to reduce QM to some mundane or classical mechanism will be defeated.

Incidentally, when I talk about quantum mechanics, let me modestly mention that the first tag in the history has earned a gold badge on the Physics Stack Exchange. Which tag was that? Yup, it was quantum mechanics. Congratulations to Bohr, Heisenberg, Dirac, Schrödinger, Pauli, and a few others, too! ;-)

Quintuplets in physics

2013-06-01T08:19:00.001+02:00

Cool anniversary: In late January, we celebrated the 30th anniversary of the announcement of the discovery of the W-boson. Today, we celebrate the 30th anniversary of the Z-boson. They were comparably important discoveries to the recent discovery of the God particle.

Sport: Viktoria Pilsen defeated Hradec, a much weaker team, 3-to-0 in the last round so we won the top soccer league for the 2nd time (after 2011). Because the Pilsner ice-hockey team has won the top league as well, Pilsen became the 2nd town in Czechia after Prague that collected both titles in the same year (correction: wrong, 3rd town, Ostrava did it in 1981).

Ms Alexandra Kiňová (23) is expecting the first Czechia's naturally born quintuplets (a package of 5 babies) on Sunday morning (tomorrow; update: they're out fine) which would mean that we match the achievement of the most fertile U.S. state – Utah – from the last week.

The Daily Mail tells us that the pregnancy has been easy so far. Doctors were still talking about "twins" in January and "quadruplets" in April. The probability that a birth produces $n$-tuplets goes like $1/90^{n-1}$ or so but the decrease slows down relatively to this formula for really high representations.

In physics, quintuplets are rare, too. By quintuplets, we mean five-dimensional irreducible representations of groups.

Correct me if I am wrong but I think that among the simple Lie groups, only $SU(2)=SO(3)$, $USp(4)=SO(5)$, and $SU(5)$ have irreducible five-dimensional representations. Let's look at them because looking at all quintuplets in group theory and physics is a rather unusual direction of approach to a subset of wisdom contained across the structure of maths and physics.

First, $SU(2)$. That's a three-dimensional group of $2\times 2$ complex matrices $M$ obeying $MM^\dagger={\bf 1}$ and $\det M=1$. The basic isomorphisms behind spinors imply that this group is the same as the group $SO(3)$ of rotations of the three-dimensional space except that the matrices $+M$ and $-M$ have to be identified.

The irreducible representations of $SU(2)$ are labeled by the spin $j$ which must be either non-negative integer or positive half-integer (only the former may also be interpreted as proper representations of $SO(3)$; the latter change their sign after a 360-degree rotation). Because the $z$-projection goes from $m=-j$ to $m=+j$ with the spacing equal to one, the representation is $(2j+1)$-dimensional.

The $j=0$ representation is the trivial singlet that doesn't transform at all; the $j=1/2$ is the two-dimensional pseudoreal spinor; the $j=1$ representation is equivalent to the usual 3-dimensional vector; the $j=3/2$ representation is a gravitino-like four-dimensional "spinvector". And finally, the $j=2$ representation is the traceless symmetric tensor. What do I mean by that?

Imagine that you consider the tensor product $V\otimes W$ of two copies of the three-dimensional vector space $V=W=\RR^3$. The tensor product is composed of objects $T_{ij}$ where $i,j$ are vector indices: it's composed of tensors. Clearly, such a tensor has $3\times 3 = 9$ independent components. They can be split into several pieces:\[

{\bf 3}\otimes {\bf 3} = {\bf 5} \oplus {\bf 1}\oplus {\bf 3}

\] The identity $3\times 3 = 5+1+3$ is the consistency check that verifies that the representations above have the right dimensions but the boldface identity above says more than just the arithmetic claim about the integers: the two sides are representations of whole groups and the identity says that they're transforming in equivalent ways under all elements of the group. Why is this decomposition right? Well, the tensor $T_{ij}$ may be divided to the symmetric tensor part which is 6-dimensional and the antisymmetric tensor which is 3-dimensional (it is equal to $\epsilon_{ijk}v_k$ i.e. equivalent to some vector $v_k$).

However, the 6-dimensional symmetric tensor isn't an irreducible representation of $SO(3)$. The trace \[

\sum_{i=1}^3 T_{ii}

\] is independent of the coordinate system i.e. invariant under rotations and may be separated from the 6-dimensional representation. The trace may be set to zero by removing it i.e. considering\[

T^\text{traceless part}_{ij} = T_{ij} - \frac 13 \delta_{ij} T_{kk}

\] and such a traceless tensor has 5 independent components; it is a quintuplet. The quadrupole moment tensor is one of the most famous applications of this 5-dimensional object. You could think it's just an accident that this number 5 is equal to the number of integers between $m=-2$ and $m=+2$; you could claim that the agreement is pure numerology, an agreement between the dimensions of two representations. But it is more than numerology: the representations are completely equivalent. The translation from the components $T_{ij}$ of the (complexified) traceless tensor and the five complex amplitudes $c_m$ for $-2\leq m\leq 2$ is nothing else than a linear change of the basis. It has to be so because for every $j$, the representation of $SU(2)$ is unique.

Now, let's talk about $SO(5)$. Clearly, this group of rotations of the 5-dimensional space has a 5-dimensional vector representation consisting of $v_i$. But what some readers aren't aware of is that the group $SO(5)$ may also be identified with the isomorphic $\ZZ_2$ quotient of a spinor-based group, namely $USp(4)$. What is this group? It's a unitary (U) symplectic (Sp) group of complex $4\times 4$ matrices $M$ that obey\[

MM^\dagger = M^\dagger M = 1, \quad M A M^T = A.

\] Both conditions have to be satisfied. The first condition is the well-known unitarity condition, effectively meaning that $s_i^* s_i$ is kept invariant (it's the squared Pythagorean length of the vector computed with the absolute values). The other condition is equivalent to keeping the antisymmetric cross-like product of two vector-like objects $s_i A_{ij} t_j$ invariant where $A_{ij}$ are elements of the (non-singular) antisymmetric matrix $A$ above. Note that in this invariant, there is no complex conjugation.

Simple linear redefinitions of the 4 complex components $s_i$ may always translate your convention for $A$ mine which is \[

A = \text{block-diag} \zav{ \pmatrix{0&+1\\-1&0}, \pmatrix{0&+1\\-1&0} }

\] You just arrange the right number of the "simplest nonzero antisymmetric matrices" along the (block) diagonal. The two conditions (unitary and symplectic) may be then seen to imply that $M$ is composed of $2\times 2$ blocks of this form\[

\pmatrix{ \alpha&+\beta\\ -\beta^*&\alpha^*},\quad \alpha,\beta\in\CC

\] and the addition+matrix-multiplication rules for such matrices are the same rules as the addition+multiplication rules for the quaternions $\HHH$. So the group $USp(2N)$ may also be called $U(N,\HHH)$, the unitary group over quaternions. In particular, $USp(4)=U(2,\HHH)$. Such a quaternionization is possible with all pseudoreal representations.

So the 4-dimensional complex (actually pseudoreal!) fundamental representation of $USp(4)$ is complex-4-dimensional (but it is equivalent to its complex conjugate because it's pseudoreal!) and it may be viewed as a spinor of $SO(5)$. It is no coincidence that $4$ in $USp(4)$ is a power of two. How do you get the five-dimensional $j=1$ vector out of these four-dimensional spinors?

Note that for $SO(3)\sim SU(2)$, we had\[

{\bf 2}\otimes{\bf 2} = {\bf 3}\oplus {\bf 1}.

\] The tensor product of two spinors produced a vector (triplet; also the symmetric part of the tensor with two spinor indices) and a singlet (the antisymmetric part of the tensor with two 2-valued indices). Similarly, here we have\[

{\bf 4}\otimes{\bf 4} = {\bf 5}\oplus {\bf 1}\oplus {\bf 10}.

\] The decomposition of $4\times 4 = 16$ to $6+10$ is the usual decomposition of a "tensor with two spinor indices" to the antisymmetric part and the symmetric part, respectively. The symmetric part may be identified as the antisymmetric tensor with two vector indices, note that $5\times 4 / 2\times 1 = 10$. And the antisymmetric part is actually irreducible here. It's because the invariant for the symplectic groups is antisymmetric, $a_{ij}$, rather than the symmetric $\delta_{ij}$ we had for the orthogonal groups, so it's the antisymmetric part that decomposes into two irreducible pieces.

By tensor multiplying ${\bf 4}$ with copies of itself, we may obtain all representations of $USp(4)$ and $SO(5)$ by picking pieces of the decomposed tensor products. That's what we mean by saying that the representation ${\bf 4}$ is "fundamental". Whenever an even number of these ${\bf 4}$ factors appears in the tensor product, we obtain honest representations of $SO(5)$ that are invariant under 360-degree rotations and all these representations may also be given a natural description in terms of tensors with vector indices.

Finally, the special unitary group $SU(5)$ has an obvious 5-dimensional complex representation. It is a genuinely complex one, i.e. a representation inequivalent to its complex conjugate:\[

{\bf 5}\neq \overline{\bf 5}

\] This representation (and its complex conjugate, of course) is important in the simplest grand unified models in particle physics. One may say that $SU(5)$ is an obvious extension of the QCD colorful group $SU(3)$. We keep the first three colors (red, green, blue, so to say) and add two more colors that are interpreted as two lepton species from the same generation. The full collection of fifteen 2-component left-handed spinors per generation (they describe quarks and leptons; a Dirac spinor is composed of two 2-component spinors; the right-handed neutrino is not included among the fifteen) is interpreted as \[

{\bf 5}\oplus\overline{\bf 10},

\] the direct sum of the fundamental quintuplet of $SU(5)$ we have already mentioned and the antisymmetric "tensor" with $5\times 4 / 2\times 1$ components. Note that the counting of the components is the same as it was for the representation of $SO(5)$ above. However, the 10-dimensional representation of $SU(5)$ is a complex one, inequivalent to its complex conjugate (I won't explain why the bar appears in the decomposition above, it's a technicality). The list of 15 spinors may be extended to 16, $10+5+1$, if we add one right-handed neutrino and this ${\bf 16}$ is then the spinor representation of $SO(10)$, a somewhat larger group that is capable of being the grand unified group (it is no accident that 16 is a power of two: that's what spinors always do).

The number 5 may be thought of as the first "irregular" integer of a sort but it is still small and special enough and is therefore linked to many special things in maths and physics. In maths, five is special because the square root of five appears in the golden ratio; and a pentagram may be constructed by a pair of compasses and a ruler (these two facts are actually related). Quadrupole moments, moments of inertia, five-dimensional rotations, and grand unifications are among the physical topics in which 5-dimensional representations are used as "elementary building blocks".

I hope that Ms Kiňová's birth will be as smooth as her pregnancy.

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