Bad Scientist

Not-so-random post about randomness

noreply@blogger.com (Giulio Pepe) — Sun, 27 Apr 2014 18:40:00 +0000

One of the most common misconception about randomness is that it is often confused with uniformity.
Could you tell which is the most random distribution of dots between the two below?

Which is random? (click to enlarge)

The most common answer would be the one on the right, which is wrong. In fact, the pattern on the right is generated by applying a small wobble (or uncertainty) on an uniform distribution. The pattern on the left, instead, has been generated using a pseudorandom [1] number generator in BASH (details in this blog post). Randomness allows for "clumps" to form and it's because of those clumps that the unpredictable behaviour of randomness comes from (unless, of course, you know the "shape" of the random distribution a priori). This appears more clearly whenever we look at the distributions shown above in 1D rather than 2D:

A random and an uniform distribution (click to enlarge)

It is clear that in the case of a uniform distribution, we have a greater level of predictability. Imagine you have a series of events which follows the uniform distribution. You are filling the histograms with events one by one by reaching 5000 events which recreate the distribution above. Whenever you approach higher numbers of events filled if there is a lack of events in one region of the histogram, there will be a higher chance for the next even to fall in that region.

You can picture in practice a 2D uniform distribution by imagining pouring a layer of marbles in a box, one by one. At the beginning their position will look random, because they can move around and take any possible position, but the fuller it gets the less available spaces there are and soon it will be easy to predict which are the only available spots for the next marble to go in.

The key thing is that whenever a position is occupied, it cannot be occupied again. This allows for a level of predictability, and this is not true of random distributions. Randomness is not predictable, its profile is unknown by definition, and it allows for the same position to be occupied again. This caused by the assumption that each random event is independent from the previous (Poisson process). Maybe this is also the reason why we believe uniform distributions to be "random". We are more familiar with those in practice and random events are either mostly abstract or harder to visualize.

This explains tendency of people to estimate randomness wrongly. This happens every time during lotteries. If a number has not come up for a long time, we feel that it is due soon. This is because we imagine random events as uniform. In fact, the probability of picking any number in a lottery is the same for every extraction, making all number equally probable to be picked, and not anyone more probable, because every extraction is independent from the previous.

An equivalent example is found in coin flipping. We feel that repeated head or tail events in a sequence of coin flips is a rare event. In fact, the chance of obtaining heads or tails is still 50% even after any number of heads have come up already. For example, events of the kind: THHTHTTHTTH and TTTTTHHHHH are equally as likely.

I created a computer-generated set of tosses to work out the frequencies of occurrences of repeated heads or tails (details on how this is done are in here). These are the results for 100000 occurrences of 15 tosses each:

3 repetitions: 93894/100000
4 repetitions: 64634/100000
5 repetitions: 34667/100000
6 repetitions: 16723/100000
7 repetitions:    7789/100000
8 repetitions: 3487/100000
9 repetitions:    1584/100000
10 repetitions: 719/100000
11 repetitions:    332/100000
12 repetitions:   125/100000
13 repetitions:   53/100000
14 repetitions:   18/100000
15 repetitions:       7/100000

15 repetitions would mean having a full set of heads or tails, which seems impossible, but it happens 0.006% of the times. In fact, over 100000 occurrences, it happened 7 times. Close enough.

The data shows that three repetitions is an event which happens almost all the times, with four repetitions more than half of the times. Up to 6 repetitions, in fact, is not that much of an uncommon event. Almost half of the sequence! I am sure it would be hard to define "random" - in the common sense - anything which has more than 4 repetitions, although this simple test shows that it's almost the norm.

Another great example of how bad we are at understanding randomness is given by this small application at Nick Berry's DataGenetics. It will distinguish a randomly generated sequences of tosses (from a real coin) from the ones you made up yourself. It is not infallible, as it is based on the Pearson Chi-squared test (so it cannot always predict which is which) and after some trials it is easy to trick it to make it believe your sequence is random. Yet, I am sure it will give you a better understanding of randomness!

[1] I have used the word pseudorandom because every computer-generated programs simulates randomness. True randomness can only be found in some not completely understood natural phenomena. Being a simulation, there are different "qualities" of generated random numbers. I am not sure about the one used in BASH, but it is usually good to stick with a higher quality random number generator for more serious business (e.g. GSL)

Some math about tipping

noreply@blogger.com (Giulio Pepe) — Sun, 24 Nov 2013 15:16:00 +0000

I went to a restaurant with friends yesterday night and since service was not included, so we decided to tip 10% (I live in the UK!).

Restaurants account for tips separately when you pay by card (some card reader have a tip option). We all paid by card separately and shared the tip equally between us. Since it would be slow to tip every one of us, the tip was added at the end and I happened to pay last, so the tip for the whole dinner was paid by me.

This makes sense as we all paid the same amount, even if it looks like I paid a smaller amount with a huge tip, leading to funny receipts as this one:

"If you really liked the service, you don't just tip 10%, but 110%"

What is even funnier, though, is the peculiarity that the gratuity was almost exactly 10% of the sale plus the original price. 10% was also our original tip on the whole dinner, so I was wondering if this happened by pure chance or if there was a connection between these two numbers.

This can be easily solved by some math:

By setting these variables:

x - total price of the dinner
n - number of people with which the dinner is shared
t - tip (in percentage)

You can describe mathematically the different way in which tip can be payed:

$ \sum_{j=1}^{n} {\frac{x(1+t)}{n}} = x (1+t) $

$ (\sum_{j=1}^{n-1} {\frac{x(1+t)}{n}}) + (\frac{x(1+t)}{n}-xt)+xt = x (1+t) $

which is at each card payment, or at the end, respectively. This holds making the assumption that the tip $xt$ is smaller than the price paid for each person $x/n$:

$ t < \frac{1}{n} $

This is a simplification to make sure only the last person pays the tip. It can get more complicated, in cases where the last person pays part of the tip and second last pays a fraction of the remaining tip. But let's stick to the easy case!

For the last person, the total to pay each (Total in the receipt), minus the tip (Gratuity in the receipt) gives the Sale, as in the receipt. Expressing this mathematically:

$ \frac{x(1+t)}{n}-xt=\frac{xt}{1+t_{1}} $

Here, I have expressed the Sale, which is on the right hand side, as the untipped amount before applying a tip $t_{1}$, which gets us the Gratuity $xt$.

So, that's where we get our answer. We have observed the peculiar fact that $t=t_{1}$. Does this happen for any amount and number of people? Which is: does this happen for any $x$ and $n$?

You can immediately notice that x (being non-zero and positive) can be removed from any part of the equation. So this result does not depend on the amount spent.

Rearranging the equation above in $t$, we get a simple quadratic equation:

$ (2-n)t^2+(1-2n)t+1=0 $

This DOES depend on $n$, which means that the result depends on the number of people. As we require $t>0$ (negative tips?!) we can also check our solution:

Close enough!

You can see that the solution is for $t$ very close to 10%, the original amount of tip. You can notice that the result depends on $n$, which is the number of people.

In fact, if you try to change the number of people in the equation, you get different results for $t$ (smaller for bigger n, smaller for bigger n).

In conclusion, this shows that it was indeed a peculiar result of chance, and it depended on how many people shared their bill.

BONUS: from the numbers in the receipt you can find out how many people I was with yesterday and how much did we spend.

Connection between derivative and integral

noreply@blogger.com (Giulio Pepe) — Fri, 05 Apr 2013 03:05:00 +0000

I remember that most of my struggle in understanding geometrical properties of calculus in first year undergrad classes was spent in working out why the integral is the inverse operation of derivative.

There are many mathematical proofs of this, which make perfect sense, but their connection is counter-intuitive as they perform seemingly different operations on curves. The derivative finds the slope at any point and the integral sums infinitesimal slabs of area under the curve. All derivatives can be solved analytically, while that is not true for integrals. Integration depends to an additive constant, while derivatives do not. Dissimilarities surely are numerous.

I have recently found this paper I wrote during my undergraduates in the quest to understand the geometrical origin of the connection between. Hope it is of any help to you, if you are having trouble in this like I had. I remember it made much more sense when I - very unrigorously - put it in this simple way:

P.S. for "Derivate" I mean "Derivative"

Research

noreply@blogger.com (Giulio Pepe) — Sat, 09 Mar 2013 02:20:00 +0000

P.S. Beware of local minima

(Brief) Hiatus

noreply@blogger.com (Giulio Pepe) — Wed, 26 Dec 2012 12:53:00 +0000

I have to heavy-heartedly announce that this blog is on a hiatus.

As you might have noticed, I have missed many FSNDs and tried to keep on but badly failed.

I will not stop writing. Maintaining a blog requires a lot of effort and I decided to put first quality over quantity, so I will write again whenever I will have more time.

Thanks for your support and see you soon.

Fortnightly Science News Digest - 31/10/12

noreply@blogger.com (Giulio Pepe) — Fri, 02 Nov 2012 19:22:00 +0000

Our nearest star has a planet:

I still remember the times when the question of our loneliness in the universe was encircled by puzzling questions on the same train of thought about the solar system and its uniqueness. We saw many stars, as we always did, but no other planets other than the one in the solar system. That made us think we are a "special" one, and being (so far, at least) the only one with life in our solar system made us even more pretentious on being unique. There was no clear answer for why apparently only our sun had planets. There are trillions of sun in a galaxy and trillion of galaxies in the universe. Why didn't we see more planets around us? That made us feel astronomically lonely and misunderstood.

It was no more that two decades ago when the first confirmed planet outside the solar system was discovered. Since then, more than 800 extrasolar planets have been discovered. The planets were there, but our technology wasn't good enough to see them, next to the luminosity of stars, often many orders of magnitude brighter than ours. The science of looking for exoplantes has increasingly become a very hot topic in astronomy. Techniques are becoming finer and astonishingly precise.

This month, it has been announced that even our closest neighbor, Alpha Centauri, just 4.3 light years distant, has a planet. And it is a small and rocky one, even if too close to the star to be habitable and to even host water in liquid form. Nonetheless, it is an amazing discovery. Alpha Centauri - being the closest star - was heavily studied and it was the natural first place to look for another planet. Yet it was never found, because its planet is very close to the star and moving quickly.

This news not only is amazing for sci-fi lovers, for which Alpha Centauri has always been target of the creative fantasy of films and books writers, and still not only from a philosophical point of view, giving hints toward a more planet-populated universe, but also for scientists. The technique to make the discovery certain had to deal with measurements with precisions on the scales of half-a-meter per second. That is slower than walking speed. And remember that those measurements are from a source 40 millions of millions kilometers away from us.

From the uncertainty of having other planets at all in the universe to the certainty of having one on our closest star, it only took twenty years. How long will it take to discover the first one in the habitable zone and with life on it?

Dinosaur feathers 'developed for courtship'

Stunning nine gigapixel image is most detailed ever of our own galaxy

5 Passwords you should never pick

noreply@blogger.com (Giulio Pepe) — Wed, 24 Oct 2012 22:18:00 +0000

I wanted to write a post about which passwords are best and how to find a strategy to pick up a good password.
Then I realized that it would be pointless, as at the same moment you tell a strategy to form a good password, it becomes an information manual for crackers and might be implemented in bruteforce methods.

What I will tell you is what are the 5 passwords you should NEVER pick.

1. password, 123456, qwerty and hunter2.

The first two are between the most used passwords of all time. There have been many passwords leaks and the Yahoo leak which was storing unencrypted passwords and usernames (foolish, I know) made possible interesting statistics: on 450,000 passwords leaked, an astonishing 0.38% was 123456 and 0.18% was password. Figure why those are the first passwords a cracker would check.

2. Vocabulary words.

Bruteforcers have already implemented methods to quickly spot those words. Even a random, only-letter 3 characters word would be safer than a vocabulary word.

3. Passwords without numbers.

Using numbers increases the possible characters used from 26 to 36, which becomes hugely significant if combined with a long password.

4. Passwords without capitals.

Using capitals doubles the possible combinations of characters, so from 26 possible permutation we would have 56, which combined with numbers would give 66. Symbols might be used as well to give extra security for smaller words, but many websites do not accept symbols in passwords.

5. L33t speak.

Crackers already know leet speak (even before normal users). They are already used to bruteforce passwords. If you don't know what it is, it is a technique to exchange letters with numbers which look like letters:

O -> 0
I -> 1
Z -> 2
E -> 3
A -> 4
S -> 5
G -> 6
T -> 7
B -> 8

This methods bypasses the vocabulary word check and potentially makes a good encryption, but it has become too popular.

This is the reason for which it is not good to tell encryption methods to form passwords. They will be used in the future generations of bruteforce software. It is much safer to create your own encryption.

Still, I can tell you a common good method which will not spoil much to crackers:

use mnemonics!

Transforming a sentence only known to you into letters and numbers will be as good as a totally random sequence of characters and numbers. For example:

I hate to wake up at 8 o'clock every Monday

will become:

Ihtwua8o'ceM

which will give ~79 bits of entropy, which is safe enough. It might seem hard to memorize but it's very easy to retrieve if you forget it and as safe as it can get. It would be one of 5.4036 x 10^23 possibilities and would take 1.7135 x 10^13 Years to discover with 1000 checks per second.

Even if this is an excellent method enough (the only problem occurs if someone manages to guess your initial sentence, which completely destroys the safety of this method, but if you did not pick up something common as the first lines of a popular song or poem, it will be safe enough) there are many other ways to create passwords which are easy to remember and require one (or more) encryption methods as the one used above. I will let you have fun with finding your own method.

But why using encryption?

It is a good method to have easy-to-remember but difficult-to-guess passwords. Of course the encryption method must be only known to you and should be memorable enough.

Another good suggestion would be not to use the same passwords for many websites. This is because some websites might not care to store passwords safely (even Yahoo, as we have seen before) and a leak will give your ultra-safe and encrypted password away, which you also accidentally use for your internet banking. Surveys say that around 60% of people use the same password for every service.

There are, of course, also methods to encrypt a memorable password for different websites and then have a set of different passwords with only one encryption method to remember. I will leave you the fun to find a good one.

Now, quickly go to change your password!

Fortnightly Science News Digest - 15/10/12

noreply@blogger.com (Giulio Pepe) — Mon, 15 Oct 2012 22:57:00 +0000

Skydiver breaks sound barrier:

it was a quite spectacular event, the one set up and performed by Felix Baumgartner, Austrian skydiver that pushed his passion a bit too far: farther than any of his colleagues before him, to be precise.

On 14 October, he jumped from a helium balloon at the height of 39,045m (breaking a world record) and reached the free-fall speed of 1,342.8km/h (breaking another world record).

With nothing on apart from his parachute and suit (which served a similar purpose to an astronaut suit), he fell freely for 93% of his 39km trip. It took less to fall for 36km (4'20") than to reach land with his parachute for 3km (4'43").

The skydiver claims he did the dive to collect scientific data on developments of high-altitude parachutes, but the event shook everyone for its spectacular altitudes.

It is fair to underline that the view from the stratosphere is not as fantastic as the one from the ISS. It is easy to be tricked by the high curvature of Earth in the pictures. Those are "fish-eye lens" picture which are distorted to include angles which would be otherwise left out. Nonetheless impressive, the height from which he jumped was still relatively very close to Earth, being only 0.6% of Earth's radius. At that height just a glimpse of curvature can be caught with perfect visibility.

In this picture, the height from which Felix jumped is exactly one pixel. I drew it on top, it might be visible with some zoom. This should give a good sense of the scales involved.

Physics Nobel goes to Serge Haroche and David Wineland

Planet with four suns discovered

The Past and the Future of Computing

noreply@blogger.com (Giulio Pepe) — Sat, 06 Oct 2012 21:24:00 +0000

It is curious how deeply computers are entering into our life.

Think of only 60 years ago and computers were very young and as big as a room. Most of the people did not own one and did not even know what was that beeping and flashing "devil's machinery".
The high potential of computers was understood soon and they grew big (not in size!) very fast to reach the consumer market in the 80s. They were still very hard to use and the graphical interface was not so graphical at all, as input and output was still mainly text.
For a decade, computers were still in a niche market of electronic lovers and programmers, and they slowly started to enter into families only in the 90s, where one computer was enough and hardly used as well.
The birth of internet was another milestone, which potential only came out later, when bandwidth started getting larger and could be used as a better method of communication than land-line phone.

Today we have smartphones. You can bring them in your pockets, they have quad cores inside and are far more powerful than thousands of old personal computers.
They are incredibly popular and, most importantly, cool.
We use them to perform loads of small tasks and we are getting always more dependent on them. They are our map, our calendar, our camera, our newspaper, our encyclopedia and, mainly, our connection to the world. We can keep in touch with a friend almost instantly, if we wanted to.

As our dependence on technology is increasing, many people wonder if this is a good thing. People are scared that technology is making us dumber, because we let them do tasks, that otherwise we would have to do ourselves, and because we know that we have a source of knowledge readily at our hand. This would let us give up on thinking about the resolution of a problem, as it could be easily looked up over the internet.

Should we give up on technology, then? I do not think that is the right approach to face this problem.
I think the problem lies in how companies are presenting technology to us, and making it addictive, for profit. What are smartphones mostly used for? Sadly, Facebook and Angry Birds. This is a bit of a downer if you think that mankind went to the Moon with computers thousands of times less powerful than our smartphone.
Unfortunately companies are making profit over games on smartphones and I think it is a big waste, as time could be well spent to improve other aspects or make "smarter" programs, which would stimulate better our brain in a less flashy and noisy way.

Also, they should teach us to use it responsibly. Technology has a great potential for doing the most amazing things, if directed in a good direction, and this is a good enough reason to not let it stop from galloping.

This reminds me of the same question we faced with calculators. Using them will not let us practice on simple math which stimulates the brain. Are they a good tool, then? Surely they are, and thanks to them we can do a much better job of calculating, in an incredibly quicker way, but the problems arise when they are getting abused. They should not be used for calculations that can be easily done mentally and, most importantly, they should not let be used to children, who need to learn fundamental mathematics.

At the same time, calculators, and computers, opened up a whole new branch, which otherwise would have not existed: programming, which stimulates logic.
Despite popular belief, technology is not a brain-killer. It can stimulate logic, design and problem-solving skills in ways that were never found before. What kills the brain is the way we use technology, how do producers present it to us.

Computers can now do a number of tasks that we could have never imagined ten years ago. We are way closer (and in many aspects, even over) to the robots age we imagined in the past. Computers can recognize human speech and work out an answer. They can crawl the web to search for information and memorize things in a much better way than humans. Many computers already are unrecognizable from humans when chatting to some testers.

But what about the future?

What scares me most is the potentiality of computers of even programming for us, in a future, which might not be that distant. Like it happened for calculators, doing basic mathematical operations for us, it might as well happen again for programming. It is already becoming easier thanks to graphical editors making it more intuitive, and its evolution could lead to completely eliminate the intervention of the user writing the code.
A smart enough computer could listen to our speech, understand the basic functions we want in a program or a script and build it for us.

This could seem like an end to programming, but if we take the comparison to calculators again, mathematics did not just die with the advent of calculators. The same way, programming could become more accessible to everyone, when the syntactic (and logical) part will be left to do to computers themselves. Creativity would surely benefit from such a change, as everyone would be able to "program", and computers will almost be like servants, being able to potentially write programs that respond to our needs.

In conclusion, I think that we live in very unique and exciting times for technological advance and the future still holds many surprises for us. Stay tuned.

Fortnightly Science News Digest - 30/09/12

noreply@blogger.com (Giulio Pepe) — Sun, 30 Sep 2012 09:13:00 +0000

Landau levels revealed: using scanning tunneling spectroscopy, physicists at University of Warwick revealed the first image of Landau's prediction for the homonymous levels. Those were predictions that made Landau win the Physics Nobel Prize in 1930, but we were only able to picture them now. Landau predicted that in a clean system, the electrons would take on the form of concentric rings. Interesting how this could also be used to give a definition of kilogram (which is still debated) as the spaces between the rings could be as universal marker for weight, being dependent on electron's mass.

Ig Nobel honours ponytail physics

'Meteors' sighted in skies across UK

Off-Peek: Radio Telescopes Edge In on Plasma Jet Spewing from Massive Black Hole

P.S.: as you might have noticed this was posted ridiculously late and it is missing description for most of the news. I apologize for the first, and about the second: from now on I decided to only write something about the first news and just post links about other major news. This is to keep the FSND feature alive as I will not have as much free time now. I just started a PhD, have mercy on me!

A picture of us all

noreply@blogger.com (Giulio Pepe) — Tue, 25 Sep 2012 15:15:00 +0000

The thing I like the most in writing science news is that the majority of the news is good news. Think of scientific research. It can only bring progress, and most of it is directed towards discovering things we can do and not things that we cannot do.

Sometimes, though, there are bad news. Exactly a month ago the first man that stepped on the moon died. A pioneer, or better, the pioneer of lunar exploration had complications after heart surgery and left us with one of the most remarkable achievements of humans, not just on the world, but on the universal scale. This is a gift not only appreciated by people in the USA, which launched the Apollo 11 expedition, but by the entire world, and consequently everyone mourned his death.

He did not like to be in the spotlight for his biggest achievement and he dropped his career as pilot (and astronaut) after his big mission. However, he did not stop from looking at the future as he started teaching in the University of Cincinnati in the department of Aerospace Engineering.

If you want to know more about his life, there are plenty of sources, and I would suggest you to do it, as it was a very interesting one, for sure, regardless of his longest trip.
What I am going to talk about here is about one of my favorite pictures of Neil:

Buzz Aldrin on the Moon. You really want to click on this picture to enlarge it.

You might be asking yourself if I it is a typo or not. And you are right, the most visible astronaut in the picture above is Buzz Aldrin, but if you zoom on his helmet's visor, you will notice a familiar reflection:

Zoomed-in visor showing reflections

And this landscape in the reflection is what makes me love this picture.
That is the reflection of Neil Armstrong, right in the middle, taking the picture of Buzz.

It is amazing to think about the trip photons had to undertake in order to form this picture. Coming from the sun, traveling through a distance of 149980571 kilometers, at around a billion km/h, roughly taking 8 minutes, to end up hitting Armstrong's suit.

In all the possible direction they could have been reflected (or absorbed, finishing their trip), they got reflected towards Buzz Aldrin's helmet. Instead of going through the visor, into Buzz's eyes, or (more rarely) being absorbed by the visor itself, they got reflected back exactly towards Neil. In particular, they got reflected towards his camera, and having passed the lens and all the components of the camera smoothly, finally they met their fate getting absorbed by the film, which is now letting us seeing the amazing pictures of men on the Moon.

But that is not all. There are at least other two amazing facts in this picture.

The first, being the "halo" around Buzz's shadow.
If you see the picture of the reflection from the visor, you will notice that the lunar grounds look lighter around Buzz's shadow. An interesting fact, which helps explaining the phenomenon, is that the halo of light is not seen in the original picture (unzoomed) where Buzz's shadow can be seen unreflected.

That is because it is an optical illusion, commonly called opposition effect. It does not just happen on the Moon, as seen here, but the high concentration of regolith on the moon increases the strength of the effect.
The opposition effect happens when the observer (or photographer) is pointing at the opposite direction of the light source (the sun). As regolith has high retroreflective properties, the zone which opposes the sun will reflect much more light and will then be brighter.
All of this, reflected back to us thanks to Buzz's helmet.

It was not just enough having Neil's reflection and a reflected opposition effect, as the picture includes something even more astounding.

Mankind in a shot

All of us are in the pictures as well, as the visor also reflects the Earth in the sky. Highlighted in the picture above, we are all there, on the pale blue dot. I can safely say that this is the only human-made picture which includes the whole of humanity (Michael Collins is in the module, which is also reflected by the visor, on the right) and in general, a picture which includes every living organism known to us.

I need to say it again: I love this picture, and I hope you can fully understand why, now. I will conclude with a touching quote about this very photo, from Buzz Aldrin, which can surely express better than me the beauty of this shot:

"As I walked away from the Eagle Lunar Module, Neil said 'Hold it, Buzz', so I stopped and turned around, and then he took what has become known as the 'Visor' photo. I like this photo because it captures the moment of a solitary human figure against the horizon of the Moon, along with a reflection in my helmet's visor of our home away from home, the Eagle, and of Neil snapping the photo. Here we were, farther away from the rest of humanity than any two humans had ever ventured. Yet, in another sense, we became inextricably connected to the hundreds of millions watching us more than 240,000 miles away. In this one moment, the world came together in peace for all mankind."

Buzz Aldrin - Apollo, Through the Eyes of the Astronauts

The curse of Productivity

noreply@blogger.com (Giulio Pepe) — Wed, 19 Sep 2012 01:30:00 +0000

It's now clear to me why I eat later and later, and become nocturnal

Fortnightly Science News Digest - 15/09/12

noreply@blogger.com (Giulio Pepe) — Sat, 15 Sep 2012 18:27:00 +0000

The Ulam spiral: when arranging numbers in a spiral, highlighting prime numbers,
they produce the (yet not fully understood) pattern showed above

Deep connection between prime numbers proved: “If Mochizuki’s proof is correct, it will be one of the most astounding achievements of mathematics of the twenty-first century.” says Dorian Goldfeld, a mathematician at Columbia University, New York. Mathematician Shinichi Mochizuki of Kyoto University, Japan claims to have proved the abc conjecture. It was one of the unsolved problems in number theory. The abc conjecture needs the concept of radicals to be understood. A radical of a number $n$, $rad(n)$ is the multiplication of the prime numbers dividing $n$ (e.g. $ 360 = 2^3 \cdot 3^2 \cdot 5$, then $rad(360) = 2 \cdot 3 \cdot 5 = 30$). The abc conjecture then states that, given three integers $a$, $b$, and $c$, such that $a+b=c$, the number $ \frac{rad(abc)^r}{c} $ is always greater than 0 for any $r>1$. The proof of this theorem is split between 4 papers and is based on many others, so it might take a while to verify, but Mochizuki was known for his deep mathematics proof and provides lot of confidence. The proof of this theorem will not only help solving similar problems in future, but also solves many other problems, such as the famous Fermat's Last Theorem.

First visible-light evidence for gravitational waves: before this discovery, an evidence for the general theory of relativity in strong gravitational fields was the measurements of binary pulsars' (a bright x-ray source) periodicity. This was achieved measuring the shrink in the period of revolution, given by the loss of gravitational waves. For the first time, the model including Einstein's general relativity has been tested in a pair of white dwarves, which has spectrum in the visible light and a significantly lower mass. Direct detection of gravitational waves could be possible with an ambitious experiment involving building an interferometer into space with arms separated a million kilometers, but connected through lasers.

Proximity-induced high-temperature superconductivity using Scotch tape: Scotch tape is proving to be a good friend to physicists, lately. After the discovery (following a Physics Nobel Prize in 2010) of an easier production of graphene, using Scotch tape, by Andre Geim, a research group from University of Toronto discovered another use of Scotch tape. High-temperature superconductivity is a property of a few materials only, which allows them to show superconductive properties at room temperature, without overheating and losing energy. Cuprates show this property, but were believed to be impossible to be incorporated as superconductors. Then, other techniques, as proximity effects were used to induce superconductivity (from Cuprates) into semiconductors, but this requires the two materials to be close in nearly perfect contact. Cuprates cannot be fabricated that way (chemically), hence here comes the tape: the team used it to tape glass slides and Cuprates to topological insulators, known to have semiconducting properties as a whole, but to be very metallic on the surface. This induced semi-conductivity into the the topological insulators, making it a first. These semi-conductors can be used to improve energy efficiency in quantum computation.

Heisenberg's uncertainty might not be that uncertain: the Heisenberg's uncertainty principle is one of the biggest pillars of quantum mechanics. A team from University of Toronto built a new experiment involving entangled photon pairs in order to try to determine the "indeterminacy" of quantum mechanics. Heisenberg is still right, but the quantitative aspect of the uncertainty was never singularly tested. According to results, the "outcome" blurred out less than expected.

Of Einstein's genius

noreply@blogger.com (Giulio Pepe) — Wed, 12 Sep 2012 20:43:00 +0000

This man oozes brainpower. Maybe not in this picture, though.

The real genius in Einstein's work is in the fact that he discovered a fundamental property of the universe from only a few assumptions.
He set the speed of light as constant in different frames of reference and developed the mathematics of Lorentz transforms further to come up with one of the most beautiful theories in physics.

While usually in physics direct evidence and data is studied to deduce a phenomenon, he inductively derived his theory having no evidence at all. He made his own axioms and derived everything again from them. And the best part is that it worked, at least in theory. Despite a few physicist immediately recognized his genius, his theories were not completely recognized by the scientific community at the beginning, especially when the paper for his theory of Special Relativity presented no references. Einstein's reasoning was outside the lines, but sharp, nonetheless, and it proved no mistakes.

Evidences for his special theory of relativity started to come up only much later, around 1932, with the Kennedy-Thorndike experiment testing the dependence of the speed of light on the velocity of the measuring device.
Direct evidences of the general theory of relativity are still feeble, even though it is now a firmly accepted theory.

No, it is not photoshopped

The difficulty in testing this theory (linked to the difficulty to discover it) lies in the fact that we need astronomically strong gravitational fields in order to detect the space-time fabric and its tiny ripples: the gravitational waves. I did not use the word astronomical by chance, as the best empirical evidences come from deep space. Usually quasars (active galactic nuclei), which are very far, but bright x-ray sources, are used as indirect test for the theory of general relativity, as their ginormous gravitational field can bend light. Pictures of galaxies behind quasars could be worked out from their light being bent right into our eyes (or telescopes), forming "rings" of light around the quasars.

A more direct evidence of general relativity would be detecting its evident result: gravitational waves. Unfortunately, these waves are far less energetic than anything we can imagine, making it easy to let them disappear into the much higher and chaotic background of radiation. Experiments exist trying to achieve the impossible through interferometers, but a much more concrete evidence, at least for now, is presented by binary pulsars.


Not the most scientifically accurate gif I could find, but surely the coolest.

Binary pulsars move into space and their gravitational field emits gravitational waves, which is a leak of energy from the system. Everything, in fact, emits gravitational waves, but for small (less heavy, to be precise) objects their emission is undetectable. As energy is leaking from the binary system of pulsars, their period of revolution will get slightly slower than usual and with enough time passed, this accumulated time will get significantly big to be measured. This is not a direct evidence, as the energetic leak that slows the period down is not necessary given by gravitational waves, but that is the only phenomenon we know that could cause it, for now, and Einstein's model works really well when applied to these bodies, so it is still evidence, even if indirect.

When I started writing this post, it was meant to be an introduction to one big recent news in science in one of the FSND series. I was so excited writing about how marvelous Einstein's theories are that it got too long and I decided that it would easily be a blog post on its own.

The news regards the recent first visible-light evidence of gravitational waves from a pair of dwarf stars, and I'll now leave you in a pointless cliff-hanger (pointless as the news is already out elsewhere) as I will talk about it in the next Fortnightly Science News Digest on 15 September.

Forthnightly Science News Digest - 31/08/12

noreply@blogger.com (Giulio Pepe) — Sat, 01 Sep 2012 14:25:00 +0000

Neil, tired but happy after the "walk" on the moon, in the Eagle lunar module still landed on the Moon

Neil Armstrong is dead: Neil did not survive after complications of an operation on blocked coronary arteries, on 25 August 2012. The man that set the first step on the moon, announcing the famous line: "That's one small step for [a] man, one giant leap for mankind" survived 82 years, but did not live in the shadow of his big mission. Before working in space and going to the moon, he was between the top pilots in the world. After, he decided to teach in Cincinnati University, continuing to inspire young students into the wonders of aeronautics. The news of his death saddened not just the US, but the whole world.

Fermilab proposes plans for neutrino experiment: having served the world of particle physics thanks to its Tevatron, a proton-antiproton collider, Fermilab is proposing a new big experiment. Tevatron closed due to lack of funds and the advent of the bigger LHC at CERN, Geneva. Fermilab proposed a new neutrino experiment five months ago, which budget would have been 1.9 billion dollars. Due to the amount of money required, they were asked to rework their plans and on the 28th of August, they proposed a new plan, requiring only 789 million dollars. The new experiment would be called Long-Baseline Neutrino Experiment (LBNE) and would research on one of the most mysterious particles: neutrinos, its oscillations (between three of his families: muon, electron and tau neutrinos) and differences between neutrinos and anti-neutrinos, which could shed some light on the CP violation, a fundamental law which could explain why more matter than antimatter exists in the universe.

Ice cover in arctic seas reaches new low: a satellite survey by NASA reported that ice cover in the arctic seas reached a new low on August 2012, taken from a sample of recordings since 1979. It is also expected to be lower on September. Scientists at NASA say the increased sea ice lost is due to the increased temperatures last year. The survey recorded a surface of 1.58 million square miles, from 1.61 million square miles in September 2007. Professor Peter Wadhams, from Cambridge University, reported to BBC News that models and calculations show that the arctic sea could become ice-free by 2015 or 2016. The alarmist view of the professor has been criticized in the past, but this new measurement could show hints toward this prediction. The ice cover getting thinner is a positive feedback system - which accelerates when it starts - as warmer temperatures caused by less ice in the seas allows the generation of storms which destroys more ice and accelerate its melt. The implications of ice-free artic seas are serious, as lack of ice would decrease the reflected light by the planet increasing temperatures even further, and causing permafrost to melt, which would release copious amounts of methane, a powerful greenhouse gas.

NASA plans new mars mission: just after a few weeks from the launch of Curiosity, the new mars rover, NASA announces plans a 425 million dollars lander which scope would be drilling into the red planet to probe its mantle, crust and core. The analysis of the interior of Mars would help understand how it evolved from the stage of incandescent ball of magma. Earth's interiors have been unveiled analyzing seismic activity, but the structure of the other rocky planets (Venus, Mars and Mercury) is mostly unknown. Mars is big enough to have developed a crust, mantle and core, but does not show the expected tectonic activity.

Fortnightly Science News Digest - 15/08/12

noreply@blogger.com (Giulio Pepe) — Thu, 16 Aug 2012 22:27:00 +0000

NASA's Curiosity rover landed safely on Mars grounds: on the 5th of August, 10:31pm PDT, after 7 minutes of terror, the newest NASA's jewel safely landed on the Mars surface. The landing itself was already a big mission and a show of the finest engineering, as the delicate equipment inside the capsule approaching Mars needed to decelerate from 21,000 kph to 0 kph without crashing on the ground. This required different systems to make the landing safe, but everything went well and the rover already sent the first high-resolution pictures from the red planet. The mission is one of NASA's biggest on Mars, due to its size and the funds spent on it. Its aim is to determine whether Mars hosted life once (or still!). The mission will last 2 years, but the plutonium on board Curiosity can provide energy up to 14 years. Hopefully, it will serve as well as Spirit.

Virtual sensation comes closer: scientists at University of Illinois, Urbana-Champaign experimented a new device which could recreate virtual sensory touch using an electronic "fingertip". The device would consist of a silicon hollow tube to be placed around the fingers with a circuit inside which could provide electrical stimuli to the fingertips simulating sensation. These circuits were built only on flat surfaces, making impossible to give a full sensory experience. The new study is experimenting and opening the way to provide sensations such as temperature, pressure and texture. The potential applications are variate, the first being giving sensation back to people who have lost it due to burnt skin.

Triumph expression is universally recognized: having seen many, recently thanks to London 2012, a study suggest that the expression of olympic triumph is an expression which is universally recognized, next to anger and happiness. Psychologists noted that it is present in cultures which have nothing in common and are different on many grounds.

The Ultimate guide to install a broadband wireless dongle on Linux

noreply@blogger.com (Giulio Pepe) — Sun, 05 Aug 2012 18:44:00 +0000

Yet another mobile broadband dongle is not working out of the box on your beloved Linux distribution.

If you are new to Linux, this might be one of the most annoying problems you will face, as there is a sea of different kinds of these internet dongles and they usually all require different drivers to be detected.

Fortunately, as almost every single wireless broadband dongle user seeks for help on Linux forums for his particular hardware, there is lot of help around from which you can guess and work out what is your problem.
But this makes the search messy, as often beginners get easily lost and reading discontinue posts on what to do is sometimes more difficult than trying to work out a solution on your own.

Check out the post on my other forum about Linux:

http://www.greplinux.net/2012/07/everything-you-need-to-know-about.html

Forthnightly Science News Digest - 30/07/12

noreply@blogger.com (Giulio Pepe) — Mon, 30 Jul 2012 10:40:00 +0000

Most powerful laser blast achieved: Lawrence Livermore National Laboratory (LLNL), a fusion research laboratory, blasted their fuel pellet with the most powerful laser beam attained in history. The laboratory, holding already the record for the biggest and most powerful laser, generated 300 trillion watts of power. The technique used by the laboratory is firing 192 lasers within a few trillionths of a second onto a 2-millimeter-diameter target in order to reach pressures, inside the pellet, high enough to generate fusion. This would release an enormous amount of energy, which is cleaner than fission. Although we can already make fusion happen, the real problem in the fusion energy research is to take useful energy from it. Nobody managed yet to do it, but scientists at LLNL hope to reach a break-even point (in which energy expenditure to fire the lasers equals energy income from fusion) by the end of the year.

Bacteria consumes waste and produces energy: A new microbial is capable of consuming organic waste and produce energy at the same time. The microbial consumes waste and an energetic potential is the end product. This technique constitutes about 2% of annual electrical American power consumption, but most of the energy produced is used to power the facilities. This is not a problem as the microbial still work on consuming waste. Unfortunately there are limits for these bacteria, as only organic waste can be consumed.

Furthest spiral galaxy discovered: Hubble spots a new furthest spiral galaxy. About two-thirds of bright galaxies discovered is spiral. When astronomers at the university of Toronto discovered it, they immediately thought of an error, being 10.7 billion light-years distant from Earth. The distance was calculated from the light-shift and that puts the galaxy to an astounding age of 3 billion years after the Big Bang. The age of the universe now is around 14 billion years and that would make this galaxy the earliest spiral galaxy every found.

Advertisements and How to block them

noreply@blogger.com (Giulio Pepe) — Mon, 30 Jul 2012 10:04:00 +0000

I have been recently using a web-browser different than mine to perform some tests and I have noticed the copious amount of adverts which I was missing. I am using an ads blocker and, without it, I have found ads even in websites I did not expect having them.

For this reason, I decided to follow the masses and join an advertisement program. Not that I want to make money from it, but I need some more motivation to keep writing.

I do not have lots of readers, even if people say I deserve more, and I always do a long work of gathering info to provide accurate information about science and technology. Do not get me wrong, I really like doing it, but it takes time, and it is well known that time is money.

For these reasons, I will put adverts in this website.

But, since I feel guilty and I know that you might be an usual reader if you are reading this, I will tell you how to remove them!

How to block ads in your web browser

I use Firefox, and the easiest and more efficient way to block ads is using an extension called AdBlock Plus.

To install it, you just need to click the install button following the link I gav above and it will handle your ads automatically.

I am sure there are extensions similar to this one also in Chrome and other web browsers.

A really neat feature is that it also blocks YouTube adverts (the ones inside videos) making generally the web-surfing experience a great deal better.

How to balance two forks on a toothpick

noreply@blogger.com (Giulio Pepe) — Tue, 24 Jul 2012 19:22:00 +0000

I posted a video a while ago about balancing forks on the rim of a cup:

This trick can be easily made using just 2 forks, 1 stick and a glass.
Your eyes won't believe it, but physics laws have not been violated in the making of this video.

The physics behind it

The center of mass of the system (forks + stick) falls around the middle of the stick, which lies exactly on the pivot.

That is the most stable position giving then stable equilibrium. Even for small displacements the system is balanced by a restoring torque.

Moreover, the system remain balanced even if half of the stick is burned, because the missing weight of the burned stick is negligible with respect to the weight of the whole system, then the center of mass approximately stays in the same position as before.

How to make it

The making of follows three simple steps:

1. Put a toothpick (or any stick that can stand the weight of two forks) between the teeth of a fork.

2. Take another fork (of the same kind) and push its teeth between the ones of the first fork. This is the most difficult bit as most of the times, the two forks and the toothpick will not stick together (you could use glue at this point without making the trick pointless, but I managed to do it without glue).

3. Put the structure on any edge, trying to find the point on which it will balance (no glue allowed at this point). You will find it by the pressure on your fingers while you try to do it. The point depends on the shape of the forks and in my case the centre of mass fell on the middle of the toothpick.

3b. Impress your friends!

iGoogle is closing down. What now?

noreply@blogger.com (Giulio Pepe) — Wed, 18 Jul 2012 13:24:00 +0000

I have been a faithful user of iGoogle for years. I did not consider it something vital and did not spend much time on it, but when I've heard the news it will close in 16 months ( November 2013 ), I realized that it was my (only) daily source of world news, weather and recipes.

Even if, by far, not the most used website, I think Google is doing a bad move here. I know many people that use iGoogle, more than Google+, honestly, and even if I understand the choice, I think Google is pointing exactly in the direction that I do not like (promoting more profitable Google products).

This is an extract from the news page:

I really like iGoogle -- are there any other alternatives?
On your mobile device, Google Play offers applications ranging from games to news readers to home screen widgets.
If you’re a fan of Google Chrome, the Chrome Web Store provides a similar range of options like productivity tools and applications to check the weather. In addition, just like iGoogle, you can personalize Chrome with a theme.

This is as helpful as convincing users to set the blank page as homepage.
First of all, I am sure there is a big number (the majority? They should know) of people using iGoogle from PCs, including me, so Google Play is useless.
For the rest, they just suggest to use Google Chrome. Please tell me where is the bit where they suggest alternatives, if you can find it.

Since Google didn't do a great job providing alternatives, I went looking for them and I can suggest a few. As trying them out is worth a thousand words, I will not spend much time describing them.

-   Netvibes: maybe the second most popular after iGoogle
-   Protopage: very easy to use, but less implementations
-   Favoor: clean interface
-   uStart: there is no possibility to share content (which I regard as good)
-   Webmag: similar to Netvibes, promoted even for non-smartphones

Forthnightly Science News Digest - 15/07/12

noreply@blogger.com (Giulio Pepe) — Sun, 15 Jul 2012 18:17:00 +0000

More hints towards the Higgs: as you might have already heard, there is lots of excitement in the field of Particle Physics because of a new discovery. As announced on a CERN seminar on 4 July, a new particle at 126 GeV of mass was discovered to 5-sigmas. The particle resembles a lot the Standard Model Higgs, which is a particle predicted by the Higgs mechanism. This model assumes that we live immersed in a field which gives mass to particles and the Higgs would be a ripple in this field, that can be detected at particle accelerators. It is not certain yet, though, if this new particle is the Higgs we are looking for. For more info about the discovery itself, you can check out my in-depth easy-language article.

Arsenic bacteria might not live without phosphorous after all: on December 2010, NASA claimed an extraordinary news, the news that life could substitute arsenic to phosphorous. There are 6 elements, without which life cannot exist, and phosphorous is one of them. Research by NASA showed that some bacteria were substituting phosphorous with arsenic and managing to live with arsenic. People were ready to "expand definition of life", but further research is showing that bacteria do not replace all the phosphorous with arsenic and there might be evidence that these bacteria cannot survive with no phosphorous at all. NASA stated that research is not complete yet.

Ocean acidification in California and CO2 in the atmosphere: scientists from Gruber's group investigate, using a model, the acidification of the waters near the California Current System, which are susceptible to ocean acidification. The increase of CO2 in the atmosphere threatens the health of the ocean and its variate ecosystem, changing the saturation state of Argonite. If you still doubt about CO2 high levels having an effect on Earth, science says they do: http://www.co2science.org/.

Magnetic cells isolated for the first time: magnetic cells are found in animals, such as birds and fishes. There are claims that these cells are used to perceive the Earth's magnetic field and have a sense of orientation (literally a sixth-sense based on magnetism). Walker et al. of the University of Auckland, performing studies on trout's nose cells, managed to isolate cells containing magnetite, which is the strongest magnet. The task was hard to accomplish because of the scarce availability of magnetic cells. As their magnetic field could interfere with each others one, each one of them is a distance apart, so only a few of those are found over a thousand normal cells. The magnetite found by the group was stronger than they expected and could also be used to get a sense of latitude and longitude (a small GPS). The next step is now to find whether this magnetic cells are linked to the brain and used for orientation.

Higgsteria - How to interpret the mass spectrum graph

noreply@blogger.com (Giulio Pepe) — Mon, 09 Jul 2012 01:20:00 +0000

The seminar on the 4th of July held at CERN in Geneva - despite the use of Comic Sans font - gave very interesting news to the Physics community.

ATLAS and CMS, two experiments from LHC, both discovered a new particle (5-sigma level is a requirement for a discovery) at 126 GeV in the mass spectrum.

Jargon apart, if you are not a physicist, you can read info about the Higgs boson (such as what is the Higgs, what is a boson, how does it give mass to other particles...) pretty much everywhere nowadays.

What many people may wonder is: what is this 5σ? And what about this 95% confidence level (CL)? But, most importantly, what is 126 GeV?
In this post I will give you an idea, with simple language, about these concepts and you will be finally able to understand this (not-so) mysterious graph.

The basics

The LHC is a particle accelerator. The scope of this machine is to literally accelerate particles (protons in this case) to very high speeds and smash them together front-to-front to see what happens.
In the case of protons, we know they have a substructure (3 quarks) and very exotic things happen when they are involved in the frontal particle accident.

In order to make these 3 quarks inside the proton interact in the collision, we need highly energetic protons. That is why this experiment is new. We needed a bigger ring (the LHC) to accelerate the protons to higher energies, high enough to allow the possibility to produce new - previously unknown - particles.

But why do we need a higher energy to produce new particles?
This is because of the sacred principle of Energy Conservation, which (to Niels Bohr's disappointment) has never been violated and most probably it will never be. Particles have mass (which is ultimately the reason for our mass) and Einstein said, through the famous relation E=mc^2, that mass is energy. When we smash the particles in the collider, the more energy we give to the particles, the more mass we can get out of the colliding particles after they recombine their internal structure.
If a particle is quite naturally heavy and the previous detector did not have enough energetic collisions to produce it, it will never be discovered!

Mass spectrum

Knowing how to produce new particles, how do you detect it and identify it? The common way is to look for particle properties and try to pinpoint it thanks to the existing model.
For example, we know that electrons have electric charge. Then, if you detect your particle and see that it has charge, you can correctly guess that it can be an electron, or any other particle having charge.

The properties we look for, to identify a particle, are mainly: charge, mass, spin. As the Higgs boson has no charge in the theoretical models, and the spin must be unitary (in order to be a boson), the best discriminator to see if the experimentally detected Higgs agrees with the theoretical models is to measure its mass.

The x-axis, Mass (GeV)

For the reasons explained above, people at CERN have been looking for a big span of collisions giving particles with different masses, in the hope to find the Higgs.

This is what you find on the x-axis of the common graph. It is the mass of the particle produced for a single collisional event.

What are the units of this mass? We are used to kilograms, what is GeV?
Einstein is again playing a role here. As mass is energy, scientists at CERN are measuring the mass of the particles in units of energy! GeV stands for giga-electronvolts, which is a billion electronvolts. An electron volt is a unit of energy (much like Joules, or Ergs, or even Calories!) which is very convenient to measure particle energy, and then also mass.

The strategy is to measure the mass of every single particle produced from the collision. As we know most of the particles in the selected mass range, we have an expectation for what the line will look like (that is the dashed line in the graph). This brings me into the next topic.

The y-axis, Number of Events

The quantity on the y-axis is the number of events observed for that specific mass. As we have an expectation for how many particles will be produced for a specific mass, if there is a new particle which has been produced, it will result in an excess of production.

The excess, of course, will be reported around the mass region for the mass of the new, unknown, particle.

This is why we measure number of events on the y-axis. Because we would expect an anomaly, a bigger number of particles produced when the energy (mass) is close to the one of the new particle, as this "new" particle was not considered in the model.

Now you can truly understand the graph. The peak around 126 GeV is the excess given by the production of this new particle, weighting around 126 GeV, which was not expected before.

But, what if it is just a mistake? It could be that the detector is not working properly or that there are so few events that there is not enough statistic and the peak is just a fluctuation around the model. This is why you need statistical evidence: the sigma.

5-sigma = discovery

As your result in the graph could be biased by low statistics or just be a work of chance, in order to shout for discovery, particle physicists usually need a 5-sigma certainty of the result. What does it mean?

Sigma is the Greek letter for standard deviation in statistics. Standard deviation is a measure of how far away is a measurement from its expectation. A result 5 sigmas away, means that it is five times the standard deviation off the expectation. And this means that, in order to be a statistical fluctuation, a measurement 5 sigmas away has a chance of one in three millions to be a random fluctuation.

This is a pretty safe assumption to make sure that the measurement is (relatively) certain!

95% CL Limit on μ

This sentence, which lies on the y-axis of the graph is not referring to the actual value on the y-axis, but it is a statement. It could be read like:

"95% Confidence Level Limit on the mean"

It means that there is a probability of 95% that the value of the measurement ( 126 GeV ) covers the true value of the parameter.
The true value is the value which we are trying to measure (the one set by God, one would say) and this is just a limit we are setting to express how much confident we are on the measurement we are taking.

What about the other weird symbols

In the graph there are two lines expressing two different set-up parameters.
I will only explain one, as the other is essentially the same.

$ \sqrt{s}=7 TeV $

is the indication of the centre of mass energy used to collide the particle. It is essentially the energy available to produce new particle after the collision. You can see that it is measured in tera-electronvolts, which is even higher than the previous scales used (giga-electronvolts), as one TeV is 1000 GeV.

$ \int Ldt=4.6-4.8Fb^{-1} $

is the integrated luminosity collected for the specified centre of mass energy. It is essentially a measure of how many collisions happened in total for the data shown in the graph.

Conclusions

What is the conclusion you can draw from the graph? Many newspaper and media were shouting for "Higgs discovered" already. Any good scientist would not.

The only certainty that the graph is showing is that a new boson has been observed at a mass of 126 GeV. Nobody is telling that it is the Higgs, even if there are strong hints towards it.

That is because the Higgs mechanism is the only good model around that could explain an excess of mass at 125 GeV. This would be a big coincidence, but there are still many particles that could be discovered and assuming the particle IS the Higgs, would actually be the most un-scientific thought anyone can have about it.

The particle could very well be something more exotic (to be read: more exotic to us!) which we could not yet explain, and actually, it is much more probable that it is.
The Higgs mechanism was built with the only purpose to explain the unexpected mass of the weak-force carriers: W and Z bosons (all force carriers should be massless in the Standard Model).
It was essentially like a back-up plan to save the most accepted model in particle physics. It was a Plan B. I would find it very improbable if it was true, a big shot of luck and intuition from Peter Higgs, even if still fascinating.

Finding a new particle's mass and saying that it is the particle you built your model for, is like finding a new skull which weights halfway between a chimpanzee's and a human's skull and pretending to have found the missing link between humans and monkeys.
There are other factors which need to be checked, so stay tuned folks and do not rush into hasty conclusions. This is an exciting time for Physics and we will have an answer soon, a definitive one.

The sad truth with vegetables

noreply@blogger.com (Giulio Pepe) — Sat, 07 Jul 2012 16:46:00 +0000

Bacon is out of scale

However easy to cook they are, there will always be a meat-alternative which is tastier.

How to recover a deleted post in Blogger

noreply@blogger.com (Giulio Pepe) — Wed, 04 Jul 2012 15:41:00 +0000

It is very easy to accidentally delete a post in Blogger, especially when mass deleting posts, as it is common that a precious post keeps a previous selection and gets deleted with the unwanted ones.

It happened to me as well. Unfortunately, Blogger does not provide any help for restoring a deleted post, but fortunately I kept a backup copy of my blog and just re-posted it again. I noticed, though, that the html link to the post was different (even if re-posted with the same date and title of the old one). It was the same as before, but with a -01.html at the end.
This is bad, because everybody who made a link to the old post now linked to a 404 Error (non existent URL).

This gave me the suspicion that Blogger stored the deleted posts somewhere, and I found a way to restore it fully, with pictures, number of views and comments.

The 5 steps to recover a deleted post in Blogger

First of all you need to retrieve your deleted post ID. If you have it, you can skip to step 4. If you don't have it, the only solution is to find it in cached web pages from search engines. For this reasons, this procedure will not work for very new posts or private blogs.
Find your old post in any search engine. For example, for my previous post, I googled "natural selection and prime numbers" and I have found the URL "http://www.badscientist.net/2012/06/natural-selection-and-prime-numbers.html". Now you need to access the cached content (click on Cached in Google when hovering with the mouse on the >>).

Access the Source code (in Firefox, right-click anywhere in the page and "View Page Source") and find this line:

<div class='post-outer'>
<div class='post hentry' itemscope='itemscope' itemtype='http://schema.org/BlogPosting'>
<a name='2003347239440929962'>a>
<h3 class='post-title entry-title' itemprop='name'>
Natural selection and prime numbers
h3>

Here, the post ID is 2003347239440929962.

Now that you have the post ID, create a new post in your blog, the usual way. In the URL bar you see above the editing fields, for example:

http://www.blogger.com/blogger.g?blogID=4658705474308031765#editor/target=post;postID=2231649307872317536

replace the number after postID with the deleted post ID. In this case, I will replace 2231649307872317536 with 2003347239440929962 .
Press Enter and your old deleted post will (magically) reappear. You can edit it again or just press Publish to have it back.

Hope this helps, let me know if there are easier ways to do that.

In order to prevent this from happening again, I revert to draft posts, instead of deleting them directly. The posts, this way, will not be on the web, but it will give me time to see if I did any mistakes before deleting a post completely.