Physics Buzz

Call me a Luddite, but...

buzzskyline@gmail.com — Wed, 11 Nov 2009 14:52:35 PST

Galileo's famous experiment reincarnated in a Wolfram Demonstration.

Ever since discovering them in my first year of college, I've been a frequent visitor to Stephen Wolfram's MathWorld and ScienceWorld. Those websites were great for when, far from my textbook, I needed to remember the value of a physical constant or what the heck Green's function does. Occasionally, the Mathematica Integrator helped smooth out a thorny integral. But they were more references than textbooks, better for jogging my memory than teaching me something new.

So I was pretty excited to see a new Wolfram webpage: Wolfram demonstrations. After downloading (for free) Mathematica Player, you can open up any number of demonstrations in subjects ranging from pure math to biology to high school physics. I was excited; I sort of love Java applets that illustrate physics concepts, and the Wolfram demonstrations page was just so colorful and full. Galileo's gravity experiments? Archimedes' principle? Not even deterred by the required online form, I signed up for my free copy of Mathematica Player and happily downloaded the demonstration of Galileo's fabled experiment of dropping balls from the top of the Tower of Pisa.

The applet showed a computer-graphic-cute Tower of Pisa, tilted over a grassy plain on a sunny day. A stick figure leaning out a top story window was holding two balls, whose masses I could change by moving a slider. I pressed play. The two balls started to fall, accelerating rather jerkily until their black pixels met the green pixels of grass at the bottom of the tower at—big surprise—exactly the same time.

It was then that I realized there was something fundamentally wrong with the idea of trying to show people this simple concept, that acceleration of a body due to gravity is not dependent on its mass, with a computer program. First of all, it's very intuitive to us that heavier things should fall faster. It just seems like it should be true, no matter how many times you've been told it isn't, right? Hold a bowling ball and a golf ball at the same height, and it just seems impossible that the golf ball will hit the ground at the same time. That's why replicating the experiment (it's debatable whether Galileo actually did it in the first place) is so much fun. Physics is surprising and counterintuitive, so seeing it at work in nature is very compelling. Only experiments can make the connection between the acceleration calculated from the equation for the gravitational attraction between two objects and an actual falling object.

Unfortunately, there is nothing compelling about a computer-generated movie that shows this. You're not going to convince any kids with this demonstration. Far more compelling would be dropping, say, a computer mouse and a CPU tower from a high window.

A Wolfram demo takes the excitement out of Archimedes' classic experiment.

Still, I'm a bit of a fan of Stephen Wolfram (anyone who tried to write a particle physics textbook at the age of twelve is sort of hard to hate) and I wanted to like this new project, so I opened up a demo that purported to reenact the experiment Aristotle carried out as a result of his bathtub "Eureka!" moment. This is a great story from the birth of science—Aristotle was charged with figuring out if a crown the king had commissioned for a temple was really pure gold. By comparing how much water the crown displaced to how much gold of the same mass displaced, he showed that the crown was not pure gold—the crown displaced a greater volume of water than the equivalent mass of gold, meaning it was greater in volume than it should have been. It had padded with a less dense metal (silver) to make the masses match. Too bad for the crown-maker.

A less messy version of the experiment is to weigh the crown in water and air and use Archimedes' principle to figure out the crown's density from the difference:

Archimedes’ Principle states that the buoyancy support force is exactly equal to the weight of the water displaced by the crown, that is, it is equal to the weight of a volume of water equal to the volume of the crown.

The Wolfram demo of this experiment is somewhat interesting visually but not enlightening in the slightest. (I even suspect that the way the author has reworked the experiment makes the whole thing trivial, but I won't get into that here, though it brings up the question how trustworthy these are as teaching resources.) Now here's an opportunity for a physicist-in-training to splash water around and relive quite a dramatic tale from Greek history. A sacred temple, a golden treasure, a treasonous betrayal—this physics experiment has it all! Seeing numbers change on a screen doesn't really do it for me, and I already know what I'm supposed to be looking for.

A Wolfram demonstration shows the compression wave in air created by a tuning fork.

True, these were only two of hundreds of demos available. A tuning fork one wasn't so bad—it lets you see air particles rarefy and compress. Compression waves are &mdsah;tough to visualize, and this makes it explicit. But you can't change the loudness of the tuning fork, or its frequency. And what about harmonics? Again, it would be more instructive to have a real tuning fork you could bang and listen to and feel.

But maybe that's because I've been reading High Tech Heretic an indictment of our enthusiasm for allotting greater and greater portions of school budgets to buying computers and hooking up high-speed internet. Believe it or not, the author isn't living in a cave, or in Amish country. Clifford Stoll, an astronomer who makes topological drinkware in his spare time, has been "digital" since the 70s. While working at Lawrence Berkeley National Lab in the 80s, he detected and relentlessly tracked down a KGB hacker who was popping in and out of networked computers on military bases around the country.

Wait, and this guy doesn't want computers in the classroom? Is this a grudge?

My knee-jerk reaction is to think that more computers in schools means greater, easier access to information. But Stoll's book points out that, first of all, schools' budgets are limited; is it really worth it to spend tens of thousands of dollars on equipment that's obsolete in two years or less, when that money could be invested into longer-lasting resources, like better libraries and talented teachers? Many proponents of computers in the classroom claim that computers can save costs by replacing laboratories, largely thanks to programs that demonstrate chemical, biological, or physical concepts—Wolfram demonstrations, for example. No toxic chemicals, no cow eyes, no costly beakers and scales—students can instead explore scientific concepts in a virtual environment. Right?

Stoll tells this hilarious story, about the daughter of an MIT sociology professor who favors bringing more computers into the classroom:

What about science? Well, Professor Turkels' seven-year-old daughter was curious about magnets. The girl had a computer program about magnets but didn't really understand them. Then Professor Turkel bought a magnet for her daughter. "Once she was holding it in her hands, she got it."

He goes on to describe a simulated chemistry lab:

School chemistry software comes complete with pretty images of thermometers, pipettes, and condensers. To simulate a titration, you type in commands, use a mouse to drag a simulated beaker across the screen, and then watch the effect on a simulated pH meter. Sure looks spiffy, but it ain't chemistry. It's simulated chemistry.

The demonstrations I found on Wolfram's site were disappointing for the same reason. It's hard to be interested in physics in a virtual world. To build these demonstrations, people took rules already extracted from nature and used them to construct a simple, boring, perfect version of nature. The more kids learn physics from computers, the harder it will be for them to actually understand that physics doesn't just exist in computer simulations in math. It governs the world of cars and people, flowers and ants, towers and bathtubs. No computer can teach that.

A modest mathematician, a not-so-modest conjecture

buzzskyline@gmail.com — Tue, 10 Nov 2009 13:55:16 PST

Grigory Perelman didn't want the money or the fame—he loved math for math's sake.

It's not often that an unemployed, middle-aged man living with his mother in the suburbs gets a write-up in the Wall Street Journal. But Grigory Perelman, a forty-something Russian mathematician who shares an apartment in the St. Petersburg suburbs with his mother, could have been a millionaire with tenured professorship in any of the top mathematics departments in the world. Instead, he turned down notoriety, tenure, and a fortune for a quiet life.

The provenance of Perelman's unclaimed million was a question posed in 1904 by Henri Poincare, the celebrated French mathematician. The famous question, known as Poincare's Conjecture, can be worded succinctly in mathematical parlance like so: "every simply-connected closed three-manifold is homeomorphic to the three-sphere." (Here's the official description from the Clay Institute—more on them later.)

The "three-sphere" in question is the skin of a four-dimensional sphere, just as a two-sphere is the curved surface of a three-dimensional sphere. Since I can't for the life of me image what a four-dimensional sphere looks like —though the language of mathematics, useful thing that it is, allows folks to consider and play with these non-existent objects—I find it easier to consider the problem in dimensions I can visualize.

People who care about problems like these are called topologists; I think of them as the type of mathematicians who never tired of the joys of playdoh. Given a doughnut of playdoh, they can mold it into a coffee mug or a teacup without having to tear it or stick pieces together together. Similarly, they can mold a sphere into a football, bend it into a bowl, or smash it into a plate. But turning the plate into a doughnut requires tearing a hole in the middle, and doing the opposite requires sticking pieces of the doughnut together to close that hole.

These shapes are not homeomorphic, but topologically distinct.

What I'm trying to get at with all this nostalgic talk of playdoh is an intuitive understanding what "homeomorphic" means. The coffee mug and doughnut are essentially the same form, so they are homeomorphic, as are the bowl and the sphere. But the doughnut can never be molded into the sphere, so these are two fundamentally different forms. Next time you come across some playdoh (I keep a little pot next to my computer in case I'm suddenly inspired to discover new topological truths) try it yourself.

What about "simply connected?" Imagine looping a string around the middle of a sphere. What happens when you pull one end of the string, tightening the loop? The loop will slip away from the middle, enclosing a smaller and smaller circumference, until it becomes a point on the surface. The same happens when you loop the string around a football. But if you loop the string through the ring of a doughnut, there's no way to shrink it down to a point without cutting it and tying it back together. So if a loop on a surface can shrink down to a single point without breaking, the shape is "simply connected."

You can smoothly shrink the rubber band around the sphere to a point, but you can't shrink the rubber band on the doughnut without breaking it.

In the dimensions we can visualize, Poincare's conjecture says that any surface on which you can shrink a loop down to a point—a football, bowl, or plate—must really be equivalent to a sphere. What Perelman did was rigorously prove that this was true if you take the whole problem to a higher dimension, so that the magic shape is the three-dimensional skin of a four-dimensional sphere.

On November 11, 2002, Perelman posted his 39-page proof on the preprint arxiv, without a care for publication in a peer-review journal or possible plagiarism. You can read "The entropy formula for the Ricci flow and its geometric applications" for yourself; Ricci flow is the mechanism Perelman used to smooth out bumps in flaw-ridden three-dimensional surfaces, revealing them to be equivalent to the smooth, curved three-sphere. His proof won him the Fields medal (many think of it as math's Nobel prize) in 2006 and a million dollars from the Clay Institute for solving one of their seven "millennium problems." Meanwhile, mathematics professors from all over the world aggressively tried to recruit him to their departments.

Perelman refused all offers. In the Wall Street Journal article, Masha Gessen, who has written a book about Perelman, tries to psychoanalyze both Perelman's successful proof and his refusal to accept the prize as artifacts of his upbringing in Russia's mathematical counterculture. This was the world outside of institutionalized Soviet math, the stables of Russian mathematicians preened, nurtured, and controlled by the state.

Whether by religion, ethnicity, or political leanings, some mathematicians could never join this institution, but that didn't stop them from doing great work. Outside of state-run research towns, mathematics was pursued as a hobby or an art more akin to poetry than engineering, Gessen writes. It was a solo enterprise, independent of academia, teaching, publishing, or professional ambitions. Although Perelman spent time in the US as a post-doc in the early 90s, those mundane aspects of American math drove him back to Russia. There, in the relative solitude—he did have colleagues and his proof rests heavily on previous work—familiar to Russian mathematicians on the outside, he worked on his proof. And he seems content to stay on the outside.

Particle physics pop-up

buzzskyline@gmail.com — Tue, 10 Nov 2009 13:56:14 PST

Nerdy science books enter a new dimension: the third. (Photo by Fons Rademakers/CERN)

Stumped by what to get for that picky particle physics buff on your Hannukah list? You're in luck. CERN is about to debut a technolust-inspiring souvenir that's science lesson and work of art all in one: a pop-up book of the ATLAS detector. Folded between its covers are Geneva, both above ground and 100 meters below, the Big Bang, and the complex architecture of ATLAS.

The ATLAS detector at CERN is a vast cathedral of electronics, wires, and materials—from semiconductor to liquid argon to scintillating plastic—enshrining the spot where two protons collide. It's not a single detector, but a series of detectors, packed around the interaction point Russian-doll style. Together they'll capture every last flicker and trace of the particles hurled out from the collision and spit out this information as hard data—about 27 CDs worth per minute.

Build your own ATLAS detector! (Photo by Papadakis Publisher.)

Anton Radevsky, a paper engineer whose pop-up ouevre includes Modern Architecture and the Wild West, reproduced the innards of ATLAS in paper panels so intricately patterned they look like stained glass windows. You can unpack and fold ATLAS's components yourself and slot them carefully in place around the interaction point—a pleasure, surely, for accelerator physicist wannabes.

As ATLAS physicists Pippa Wells quips in the above video posted on YouTube, the feat takes about a minute, but ATLAS was 15 years in the making, from concept to commissioning. And while the book only requires a bit of uncomplicated folding, the actual construction required lowering ATLAS piece by piece from the surface down through two shafts to the tunnel floor, 100 meters below ground, and then assembling it. Here's the whole process condensed down to a minute of action:

As CERN readies itself for the magic moment when protons circulate in the tunnels and collide, tensions are high and excitement is building. It's taken more than a year for the thousands of people involved in the project to return the LHC to the point it was at last September, and the media and public seem skeptical that it will all come through. The LHC seems to be all about bigness and grandeur—it's 27 kilometers in circumference, and a single bit of ATLAS weighed 250 tons—but it's incredibly delicate and vulnerable. Last Thursday CERN made news when a bird snacking on a chunk of baguette dropped it into a high voltage component, causing a power cut. Cooled magnets threatened to warm up; the press cackled gleefully.

The accelerator is due to fire up later this month, and everyone's thinking the same thing: will it work? Bill Bryson, in a refreshingly down-to-earth piece of writing chronicling his recent visit to the lab, has it from the mouth of the LHC's head of operations: yes, without a doubt.

While you wait, though, better get on with that Hannukah shopping: you can preorder "Journey to the Heart of Matter" (not yet available on Amazon) at the website of publisher Papadakis.

Heaven on Google Earth

buzzskyline@gmail.com — Fri, 06 Nov 2009 15:21:16 PST

Yesterday I talked about using Google Earth to get a sense for the grandeur of the huge, landscape-sized machines of experimental particle-physics. But Google Earth is also perfect for touring the holy sites of the other big science, astronomy, whether you want to check out the world's biggest telescopes or explore the stars.

First stop: in the "Fly To" bar, type in "Very Large Array." Before you know it you'll be descending on a dusty, desolate patch of New Mexico that's home to 27 telescopes, each laden with a 25-meter-wide dish. The VLA is part of the National Radio Astronomy Observatory and "see" the universe in radio waves just as we see the world in visible light, allowing astronomers to study anything from the Cosmic Microwave Background to stellar corpses known as pulsars. Some of the data collected by these telescopes has even found its way into Google Sky.

The Very Large Array in New Mexico.

Apparently the Google Maps truck barreled down at least on dusty road in the complex; enter one of the photo-bubbles and look around. You're standing at the edge of the array with one of the giant listeners looming over you, dish cocked to receive a message you can only guess at. Pretty impressive.

One of the Very Large Array's telescopes, up close and personal.

Next, click the "Add Content" button on the Places bar. This will open up a window in the bottom half of Google Earth that lets you search extra material. Search for "Chandra X-ray Observatory," download the file that comes up, and open it in Google Earth. It will become a folder under places. Double click, and you'll fly over to the air above Cape Canaveral, where you'll see the purple-winged (actually, they're solar panels)Chandra hovering.

The Chandra X-Ray Observatory, hovering over the Kennedy Space Center.

The scale isn't quite realistic—Chandra's elliptical orbit takes her to an altitude that's about a third of the way to the moon, and she's not always above Flordia—but it's convenient for zooming down onto the Kennedy Space Center just below her and checking out the launch pad.

Now it's time to head down south. In the browser window, go to the Pierre Auger Observatory's Google Earth Page, where you can download a model of the cosmic-ray observatory and open it in Google Earth. Spanning an area of the Argentine Pampas that rivals the size of Paris, Pierre Auger uses 1600 water tanks to catch secondary particles from cosmic-ray showers. The Google Earth package is wonderful because you can really get a sense for the vastness of the enterprise, and how amazing it must be to stand on that desolate plain with the Andes looming in the distance.

The 1600 cosmic-ray detectors of the Pierre Auger Observatory in Argentina.

Tropical climes are next. Fly To Mauna Kea on the big island of Hawaii. Zoom in a bit and you'll likely see a cluster of enormous white domes: the Mauna Kea Observatory , home to the northern telescope of Gemini (the other is on the summit of Cerro Pachon in Chile) and the two telescopes of the KECK Observatory. In your "Layers" menu, turn on 3D buildings for a treat—the twin domes of KECK in 3D.

The KECK Observatory's twin telescopes, on Mauna Kea, in Hawaii.

Finally, "Fly To" Canary Islands and watch Chandra whip by as you zoom across North America to land in a remote, northeast corner of the Atlantic. Once you're there, "Fly To" Roque de los Muchachos, Canary Islands. When you land in a deep ravine covered in plant life, zoom out a bit. You'll spot a white dome in the upper left of your screen. Go to investigate—it's the Roque de los Muchachos Observatory, home to an impressive suite of telescopes, including the world's biggest optical eye on the sky, the Gran Canarias Telescope.

The telescopes of the Roque de los Muchachos Observatory on La Palma, Canary Islands.

Plenty of the telescopes have been modeled in 3D, so make sure to turn on 3D Buildings. This shot of the Gran Canarias Telescope is as pretty as a painting.

The Gran Canarias Telescope on its perch overlooking the Atlantic.

Once you've had your fill of astronomy on earth, go to Google Sky, Moon, and Mars to do your own exploring.

Google Earth your way to big science

buzzskyline@gmail.com — Thu, 05 Nov 2009 15:45:26 PST

I remember how excited I was when Google Maps first came into existence. I would seize anyone who seemed to show a particle of interest, sit them down in front of my computer, and click madly on the little square until I could discern my own house.

Well, Google Maps has grown up quite a bit since then. Now I can satisfy my need to stalk my own house by flying straight home on the wings of Google Earth. When that gets boring, I can zoom way out and give the earth a spin, as if it were an old-fashioned globe, or turn it upside down to check on Antarctica.

Google Earth is also a great way to tour big science in all its glory. How, you ask? Well, first download the program. Then make a list of your dream destinations —Fermilab, CERN, KEK in Japan, SLAC National Accelerator Laboratory—and fly to each one.

SLAC National Accelerator Laboratory makes for a splendid aerial shot, even more impressive than the giant rings of Fermilab's Tevatron or the LHC. The two-mile-long linear accelerator ends in a fan of buildings that once housed enormous detectors that helped scientists probe inside the nucleus, among other things. The smaller ring you see is the Stanford Synchrotron Radiation Lightsource. You might notice that parts of the lab seem to be under construction— it seems like these images were taken when the lab was excavating for the Linac Coherent Light Source. This year the nearly half-century-old linac was reborn as the world's first hard x-ray free-electron laser.

The SLAC linac from above. Electrons start their journey at the left end.

Conveniently, Interstate 280 spans the accelerator. Use "street-view" to land on the freeway and look down at the accelerator's klystron gallery, the building that houses the accelerator's above-ground workhorses.

The accelerator from the I-280 freeway.

Next, wing it over to Fermilab. You'll see the patchwork of wetlands, woodlands, and grasslands that make up the 6,800-acre campus clearly marked by the distinctive white ring of the Tevatron, flanked by its booster ring. Are those fuzzy brown spots I'm seeing bison? They might be. Check the option for 3D buildings so you don't miss a pretty impressive 3D construction of the lab's famous Wilson Hall, with its curving walls and sentinel of international flags, a reminder of the cosmopolitan nature of particle physics.

Wilson Hall at Fermilab, rendered in 3D.

If the architecture inspires you, why not help Fermilab name their next accelerator? It's called Project X right now, but they're looking for something with a little less science fiction and a little more personality.

Here's a place you may not know much about: KEK, the high-energy physics lab in Tsukuba, Japan. You'll identify it from the air by its ring-shaped accelerator, the powerful KEK-B. It collides electrons and positrons for a collaboration known as BELLE. (Latitude: 36° 9'15.90"N, longitude: 140° 4'18.67"E)

The KEK-B electron-positron collider in Tsukuba, Japan.

Brookhaven National Lab is also distinctive aerially—check out the the Relativistic Heavy-Ion Collider at latitude 40°52'36.42"N, longitude 72°52'19.09"W.

Fearful symmetry

buzzskyline@gmail.com — Wed, 04 Nov 2009 15:28:13 PST

Tyger! Tyger! burning bright
In the forests of the night,
What immortal hand or eye
Could frame thy fearful symmetry?

—William Blake, The Tyger

Evariste Galois is perhaps one of the most romantic figures in mathematics. While still in school, he sent his great breakthrough in geometry to established Parisian mathematicians; unfortunately, the breakthrough was written out in such an ungodly scrawl that the wise men had no idea what to make of it. By the age of twenty, he was languishing in prison for his revolutionary acts (political, this time); with cholera threatening, he and other prisoners were sent to a clinic where he fell in unrequited love with a doctor's daughter. Then, on May 30, 1832, he died of a wound from a gunshot fired in a duel that arose under murky circumstances.

The night before, realizing that he might not have another chance, Galois did some major cramming. He gave his best shot at explaining his ideas about geometry in the clearest language he could muster. (The name of his beloved, Stephanie, dotted the margins.)

"Maybe the fact that he stayed up all night doing mathematics was the [reason] why he was such a bad shot the next morning and got killed", said Marcus du Sautoy in his TED talk on Galois and symmetry at the 2009 TED global conference. But du Sautoy, an Oxford mathematician, owes Galois quite a bit. The young mathematician discovered the rules governing symmetric shapes, shapes that can be rotated and flipped and look unchanged. Du Sautoy calls these manipulations the "magic trick" changes. "For Galois symmetry was all about motion, what can you do to a symmetrical object so it can looks the same," du Sautoy said.

Symmetry, Marcus du Sautoy says, is "nature's language." It arranges the atoms in a ruby, and the piles of molecules that form a virus. Humans consider symmetric faces to be beautiful, he says, because symmetry, being difficult to achieve, is a token of strong genes and the sign of a desirable mate.

When Spain was under Muslim rule in the mid 14th century, the rulers built themselves a splendid palace known as the Alhambra, or the red fort. Because Muslim artists were forbidden from depicting animals or people, they found beauty in patterns and symmetry. Using Galois rules, you can determine that the gorgeous, intricate mosaics on the walls of the Alhambra contain 17 different kinds of symmetry in all, making it a treasure-trove for mathematicians. (A paper on the geometry of Islamic art appeared in Science in 2007.)

Walls and ceiling of the Alhambra. (Justus Hayes/Shoes on Wires/shoesonwires.com)

Du Sautoy goes on to say that there's no stopping mathematicians from using Galois rules to go beyond three dimensions.
His breakthrough, du Sautoy says, "allows us to create symmetrical objects in the unseen world"—four, five, six dimensions and more.

"That's where I work," he says. "I create mathematical objects, symmetric objects using Galois' language in very high dimensional spaces."

As a final treat, du Sautoy named a new mathematical object he'd created after the person who could get closest to estimating the number of symmetries in a Rubix cube. (Try it yourself - he gives the answer at the end of the talk.) Of course, you can't see a symmetric object in twelve dimensions, so the winner had to be content with a picture drawn in Galois' mathematical language.

If you fancy having your own multidimensional symmetrical object named after you, you can donate $10 to a Guatemalan charity that du Sautoy supports. He will then "stay up all night" building a new intangible, symmetric toy to stick your name on. He's raised about $3,000 this way—that's a lot of late nights!

What is reality?

buzzskyline@gmail.com — Tue, 03 Nov 2009 12:25:52 PST

As a child, Anton Zeilinger used to pull the heads and limbs off his sister's dolls. "I liked taking things apart," he explained in an interview with the Institute of Physics (see video below). This childhood tendency grew up into scientific curiosity; Zeilinger is now a well-respected physicist, the head of a quantum optics group at the Institut fur Quantenoptik and Quanteninformation in Vienna.

We generally believe that Zeilinger can satisfy his scientific curiosity through experiments, either by doing his own or by learning of the results of others' work. When we ask nature a question, she will answer truthfully, as long as we ask the question honestly and know how to interpret her response. Our observations, then, can create a picture of reality, mapping the facts of the world "out there" in one-to-one correspondence with ideas in the mind "in here."

In a talk at the recent Quantum to Cosmos Festival at the Perimeter Institute in Waterloo, Ontario, Zeilinger raised a question that might seem, at first glance, naïve.

"What do we really describe in physics?" he asked. "Do we describe reality? Is it out there?"

Classical physicists would have said yes, resoundingly. Studying physics reveals nature's workings, providing an explicit map of reality's subtleties. Those subtleties would be there whether we figured out how to question and extract them.

But in the early part of this century, quantum mechanics put that happy belief on the chopping block. Quantum mechanics, for all its ability to describe the atomic and subatomic world, blurs the distinction between the observer and the observed. As a result, it calls into question the essence of scientific curiosity and inquiry.

According to quantum mechanics, an electron's position is a smattering of possibilities. It's likely to be found, perhaps, within a certain boundary, and less likely to be found outside it. When we ask the electron where it is, this smattering will collapse into a definite value.

But what about the electron before we observe it? What is the reality of the electron? Einstein believed that the electron must know where it is. And Heisenberg's uncertainty principle only makes this little gedankenexperiment more preposterous for classicists: once we know the electron's position, we can know nothing about its momentum.

Einstein believed that this was evidence that quantum mechanics was in some way incomplete. His formal argument is known as EPR, for his collaborators, Podolsky and Rosen. Joshua Roebke writes in an article in SEED on Zeilinger's work:

The EPR paper begins by asserting that there’s a real world outside theories… EPR argued that objects must have preexisting values for measurable quantities and that this implied that certain elements of reality could not be determined by quantum mechanics.

Quantum entanglement is one particular case that wreaks havoc on Einstein. In his talk at Quantum to Cosmos, Zeilinger explained the effect:

If you have a pair of dice that are quantum entangled—you can't buy them yet but I'm sure in a hundred years you can buy them as a Christmas present—a pair of quantum dice would be such that if you throw one die here and one die there they always show the same number. Now this can only be if they have a common cause, or if they are talking to each other somehow.

Zeilinger studies entanglement with photons; in lieu of the face of a die, the photon's polarization is the property in question. Separate two entangled photons by a galaxy, then have an observer measure the polarization of each. They will see the same polarization.

In 1997, Zeilinger demonstrated this effect in the lab; it was hailed as "teleportation," with information (the photon's polarization) being beamed instantly from one particle to another. In 2007, he demonstrated in spectacularly across two of the Canary Islands. It's as if one photon, the moment it was measured, sent an instantaneous, light-speed-limit-breaking signal to the other, telling it what polarization to have; accepting this non-locality would allow physicists like Einstein to hold onto realism, the idea that the photons must have a determined polarization before they are measured.

A physicist named Anthony Legget formulated this possibility into a testable theory, which he brought to colleagues who brought it to Zeilinger's lab. To Legget's chagrin (quantum entanglement upsets him nearly as much as it upsets Einstein), fastidious experiments proved that this wasn't the case (for further reading, see the full text of "Reality Tests"):

It took [Zeilinger and his colleagues] months to reach their tentative conclusion: If quantum mechanics described the data, then the lights’ polarizations didn’t exist before being measured. Realism in quantum mechanics would be untenable.

"What this tells us also in a deeper way is that there are situations where what we observe in experiment is not some reality which was there before," Zeilinger explained in his talk at Quantum to Cosmos. "Our experiment creates reality in a sense. What is then reality, really? What are we describing now with physical theories?"

In his talk, Zeilinger suggests that physics sorely needs new ideas that can comprehend these facts. "I mean, quantum mechanics is a hundred years old. Relativity is a hudnred years old. A new breakthrough is due," he said.
For Zeilinger, that new idea that makes everything clear might be the unification of these two big theories, something physicists have been grappling with for several decades now. Or it might involve another sort of unification altogether.

"Maybe we have to unify the idea of reality and information, which is my own personal theory," he said.

Right again, Einstein

buzzskyline@gmail.com — Mon, 02 Nov 2009 15:28:36 PST

Gamma-ray tie: Einstein wins. Photo from NASA.

On May 10, 2009, two photons reached the end of a 7.3-billion-year race at a detector on the Fermi Gamma Ray Space Telescope. First one photon blinked into the Large Area Telescope's detector ; then, 0.9 seconds later, the second photon crossed the finish line. The second photon had been beaten by a whisper; divide that truncated second by the 7.3 billion year journey, and you'll see that their traveling times differed by less than one part in one hundred million billion (that's 10^-17 for fans of scientific notation).

Both photons were gamma rays, from the most energetic end of the electromagnetic spectrum, up to 300 billion times more energetic than visible light. They were from the same gamma-ray burst, a blast of radiation from the collapse of a massive star far in the past (and away from us in space.)

All this is to say, score another point for Einstein, the obscure patent clerk turned physics giant, and for the invariance of light speed.

In a vacuum, Einstein said, all electromagnetic radiation should travel at the same speed. Glass or water slows down light, but in a vacuum, even to an observer on a speeding rocket, it always travels at 299,792,458 meters per second.

Four years ago, things didn't look so good for Einstein. In 2005, the MAGIC telescope on the Canary Islands recorded the last-place finisher in another galactic race, 500 million years long, as lagging four minutes behind. This seemed to support some cosmologists who proposed that higher-energy photons might travel more slowly than lower-energy photons.

Einstein's general theory of relativity is immensely powerful, but it's still fundamentally classical. Einstein bristled at the very idea of quantum mechanics, which makes it meaningless to speak of a photon's properties before one observes that photon, collapsing the probabilistic wavefunction into a definite value (and rendering another property entirely unknowable, as in the case of position and momentum.) The onus on modern theoretical physics is to reconcile Einstein's picture of gravity with the other greatest theory of the twentieth century, quantum mechanics.

Quantum mechanics says that energy is quantized. Some proponents of loop quantum gravity think that space-time, too, comes in fundamental chunks. If you could shrink down so that 10^-35 meters was a comfortable walking distance, they say, you wouldn't see that silky smooth "fabric" of space-time everyone talks about. Instead, you'd be tossed and battered by a swirling sea of Planck-scale foam.

Since higher-energy photons have shorter wavelengths, some cosmologists say, they might be more vulnerable to this fluctuating foam, while lower-energy photons' longer wavelengths would keep the sailing smooth. As Dennis Overbye at the New York Times puts it:

One way to think about it is to envision the photons as boats on this choppy sea. The small ones, like tugboats, have to climb up and down the waves to get anywhere, while the bigger ones can slice through the waves and bumps like ocean liners, and thus go a little faster.

On small scales these slight differences would be negligible. But after long distances, the tiny discrepancy in velocity would start to become visible. The lower-energy photons would begin to pull ahead, and the higher-energy photons would start to fall behind. Fermi, with its ability to make precise gamma-ray detections, is one of the few telescopes that can observe this kind of lag. The most recent results set a limit on how much a photon's energy could change its speed.

But how did MAGIC get such a different result? Rachel Courtland at New Scientist explains:

The MAGIC time delay may be down to an astrophysical process where particles are accelerated to enormous energies within the hearts of galaxies. Follow-up calculations after MAGIC's 2005 result showed that is possible to produce flares that release lower-energy radiation before higher-energy radiation, according to MAGIC collaborator Robert Wagner of the Max Planck Institute of Physics in Munich, Germany. "I think what we can say for the time being is quantum gravity effects cannot be the dominant effect," he says.

The man may not have believed in quantum mechanics, but for now, chalk up another point for old Einstein.

Halloween party physics

buzzskyline@gmail.com — Fri, 30 Oct 2009 12:20:01 PDT

"Sure looks like a lot of fun in there, doing all those physics experiments."
http://www.flickr.com/photos/vintagehalloweencollector/ / CC BY-NC-SA 2.0

If there's one holiday that seems tailor made for the physics enthusiast (besides Pi Day), it's Halloween. You can trick out your home or Halloween party with spooky effects and decorations, courtesy of science and a few readily-available ingredients.

Blacklights

The light coming from these bulbs isn't black at all, but ultraviolet. We can't see ultraviolet light; instead we see a violet glow (ultraviolet light's visible neighbor on the spectrum) from the bulb, and a white glow from teeth and white shirts and socks. That's thanks to phosphor, an element that glows in the visible spectrum when excited by higher-frequency wavelengths (confusingly, this phenomenon is called fluorescence.) Laundry detergents contain phosphor to make white clothes seem brighter in sunlight, and phosphor is second only to calcium as the most abundant mineral in the body and is found in our bones and teeth. Phosphor is also responsible for the fluorescent colors of highlighters. Buy some blacklight bulbs, hang a huge sheet of butcher paper along one wall, and play fluorescent pictionary with highlighters.

Dry-ice burn and cauldron bubble

Here's a recipe for a bubbling cauldron that requires neither eye of newt nor toe of frog, nor wool of bat nor tongue of dog. The main ingredient is dry ice—frozen carbon dioxide. Start with a juice-based punch, and the dry ice will add both carbonation and spooky smoke to your jungle juice as it sublimates.

Concoct your punch as desired at room temperature—this will make the sublimation more dramatic. Add large chunks of food-grade dry ice once your guests arrive for a spectacular smoky effect. (This site recommends 3-5 pounds for a big bowl.) For a floating hand, freeze a latex glove full of tonic water and add it to the mix.

Is using dry ice dangerous? As with anything fun, it requires a bit of caution, but in a word? No. Dry-ice is much colder than regular ice; at standard pressure, carbon dioxide freezes at about -110 Fahrenheit. That's freaking cold, and is likely to burn you if it touches your skin, so wear thick rubber gloves. For that reason, and one other, you should not serve your guests any solid ice when you're ladling out the punch. Even if it's water ice that's formed as a result of cooling, it could enclose a nugget of dry ice which would rapidly expand to enormous volumes once ingested, via PV=nRT. (Dry ice in a closed container also becomes a terrible idea in about two seconds.) So don't serve up any solids. Finally, using food-grade dry ice will guarantee it's free from impurities—your punch won't get any added "flavors" besides the same carbonation found in soda. (Read this "Ask a Scientist" column from Argonne National Lab for more about dry ice safety, and here are a few additional tips on achieving smoky effects at home.

These unsuspecting peeps will soon be at the mercy of your mad physicist whims.
http://www.flickr.com/photos/sis/ / CC BY 2.0

No peeps were harmed in this experiment

This little experiment really brings out the kid—and the evil scientist— in me. You'll need a bell jar and a hand vacuum pump—think of it as investment in endless amusement.

Place an unsuspecting Halloween peep in the bell jar, ask an assistant to hold the lid tightly to the bottom of the bell jar, and start pumping out air. As the air pressure drops in the jar, the air bubbles in the peep expand, bloating the peep to (relatively) monstrous sizes.

At this point you can challenge your brawniest friend to pry the lid off; the air pressure on the outside of the bell jar will likely foil your friend's muscle. Then unscrew a small valve in the pump's tube to let air back into the chamber suddenly—it will crush the peep. Luckily, it will still taste just as terribly, terribly good.

Other physics recipes for Halloween making a statue whose eyes seem to follow the viewer , magic two-way mirrors, and slime.

Nightmarish physics

buzzskyline@gmail.com — Thu, 29 Oct 2009 19:13:55 PDT

A nightmarish image?
http://www.flickr.com/photos/agelakis/ / CC BY-NC-SA 2.0

On some nights, physics haunts my nightmares. I dream I'm once again in my last week ever of university. I have an exam in a few hours on perturbation theory in quantum mechanics—but I haven't been to a single class all year. The nauseating certainty of "I'm never going to get my bachelor's degree!" feels so real that I often wake up wildly thinking how I'm going to get my hands on some course notes. And this is two years after the fact.

I'm probably not the only one who's had nightmares about physics tests or felt trepidation at the thought of approaching a particularly thorny professor during office hours. But physics itself is rife with terms that sound menacing. I mean, just look at the Large Hadron Collider—all they did was name it literally after what it does, yet the name couldn't be more ominous. So in the spirit of Halloween, let's take a look at some of the seemingly nefarious terms found in physics and see if the fright is real or just in the name.

Destructive Interference

Light waves interfere to form patterns of bright and dark lines, which correspond to where they interfere constructively and destructively, respectively.

Sounds like: a bureaucratic euphemism for spy work in East Berlin. More like: a humdrum phenomenon. When waves—light, sound, you name it—overlap, sometimes they are perfectly out of synch, with a peak of one wave occurring in the same place as the trough of another. When this happens, the waves cancel out; in a tank of water, you'd see a smooth surface. This is destructive interference—the interfering waves destroy each others' amplitude. In constructive interference, where the waves line up perfectly, they construct larger peaks and deeper troughs. Verdict: not scary.

Maxwell's demon
Sounds like: a 19th century poltergeist. More like: a thought experiment by 19th-century father of electromagnetism, James Clerk Maxwell. A demon crouches atop a box filled with a gas at some temperature. He places a partition across the box, dividing it into two halves; the partition has a little slot the demon can open and shut. The demon watches the gas molecules approach the barrier. When a slightly slower-than-average molecule approaches the barrier from the left, or a slightly faster-than-average one approaches the barrier from the right, he opens the door. Eventually, working exactly in opposition to the second law of thermodynamics, he separates the molecules into two gases with a temperature difference, which can be used to do work. Verdict: Not scary, unless you consider an implication of the fact that Maxwell's demon doesn't exist: heat death.

Dark energy
Sounds like: an evil power fighting against Sailor Moon. More like: the poorly-understood mechanism for why all the galaxies in the universe are accelerating away from each other. Verdict: not scary in itself, but it's kind of scary that dark energy is deciding the fate of the universe, yet we know almost nothing about it except that it's there.

Ultraviolet catastrophe
Sounds like: face-melting radiation. More like: One of the first huge clues that classical physics, which, at the turn of the century, felt so secure in its understanding of nature, didn't have the whole story. Classical physics predicts that the intensity of light emitted by a heated object scales up infinitely with the frequency. This would mean that sitting next to a fire would leave you charred. The failure of classical physics to explain the actual relationship, which peaks at a certain frequency depending on the temperature, and then slides back down at frequencies higher than that, opened the door for quantum theories. Verdict:Absolutely terrifying—if you're a classical physicist.

Klystron

One of 242 klystrons powering the beam at SLAC National Accelerator Laboratory

Sounds like: an alien race, intent on destroying humanity. Actually is: a really big microwave. Klystrons are the engines of particle accelerators; they produce microwaves, which are funneled into the accelerator cavity to give particles a kick.
Verdict: They look sort of scary, but they come in peace.

Nemesis
Sounds like: an intergalactic force, intent on destroying humanity. Actually is: an intergalactic force, intent on destroying humanity. Well, sort of. In the '80s scientists proposed that a star was responsible for periodic mass extinctions on Earth. They theorized that the star, as it swung by every 32 million years or so, flung comets toward the inner solar system. They dubbed the star Nemesis.
Verdict: Pretty frickin scary, if it weren't for the fact that scientists have largely discarded the idea.

Heat death of the universe
Sounds like: the fiery end of all creation. More like: the slow, plodding, inevitable end of all creation. According to the second law of thermodynamics, the universe's entropy only increases. It's a familiar concept with a lot of relevance to life; a baseball can smash a window in one second, but all the king's horses and all the king's men couldn't put it back together again. The second law acts in the opposite way of Maxwell's demon; dump hot and cold gas into a container, and you'll always get lukewarm gas. Take this idea to it's logical conclusion, and you'll realize that eventually the universe will reach a point where all reservoirs of hot and cold mix, reducing the universe to a lukewarm bathwater from which no useful work can be extracted. That means definitely no life. Verdict: scary, but it's billions of years away. Does put certain things into perspective, though.

Project Monster
Sounds like: A CIA plot to unleash a frozen dinosaur on enemies of the free world. More like: The nick name for the Stanford Linear Accelerator when it was being dreamed-up and built in the 1960s.

Runners up: Project X, Krypton, and Landau ghosts, which let physicists write papers with titles like "Exorcizing the Landau Ghost in Non Commutative Quantum Field Theory."

Liftoff: historic moment or false step?

buzzskyline@gmail.com — Wed, 28 Oct 2009 15:04:33 PDT

At 11:30 this morning, NASA scientists and the world witnessed the birth of the America's next-generation human space exploration program with the successful launch of the Ares 1-X test rocket. Sleek, clean-lined, and delightfully futuristic, the Ares 1-X tapers to a needle-like apex 327 feet above its base. By comparison, the space shuttle we've seen launch from pads at the Kennedy Space Center since 1981 looks like a dowdy maiden aunt.

Ares 1-X is shaped something like a hypodermic needle; after the rocket itself had burned out its fuel, about 25 miles above the ground, the first stage (the plunger of the needle) fell away, while the upper stage continued another three miles into the air. Tucked just beneath the upper stage's needle nose was a mock-up crew module, which the upper stage carried up another three miles before they fell back toward earth.

The launch simulated the first two minutes of a flight of Ares 1, the rocket NASA has designed to replace the shuttle in shipping crews to the International Space Station. Instead of holding a dummy crew module, the nose of Ares-1 would enclose the Orion crew vehicle, a versatile ship that could dock at the ISS and rendezvous with the planned lunar lander Altair before embarking on a moon mission.

By all accounts the launch, which had been stymied by bad weather, was a success. The rocket's hundreds of sensors took data on the stresses of take-off, providing engineers with invaluable information for improving their current design for Ares 1. Video streamed on NASA TV showed the team at Kennedy, dressed in the awkwardly formal engineer-in-the-public-eye uniform of white dress shirt and patterned tie, jovially shaking hands; according to the NASA tradition for successful launches, the launch director had his tie ceremonially clipped by a pair of scissors.

Today's launch might turn out to be a historic moment that people recall decades from now when the first human sets foot on Mars. Or it might turn out to be a $445 million foray down a blind alley. Just last week, a review panel plainly refuted the idea that NASA had the budget to move forward with Constellation, its program to put humans back on the surface of the moon and sending them on to Mars.

The tip of Ares 1-X towers 30 stories above the launch pad. (Photo by NASA.)

According to NASA, the return to the moon with Constellation wouldn't be to leave a historic footprint, but explore the moon, study its geology and resources, and eventually build an outpost, a more far-flung version of the ISS. The Ares 5, the Ares 1 hefty older brother, is being designed to carry building blocks of such an outpost into the heavens. This lunar mission, NASA hopes, would provide the agency with the know-how for an even more ambitious mission—putting humans on Mars.

Even with hopeful spin NASA puts on the idea in this educational video, a mission to Mars sounds incredibly daunting. It would take six months to get to Mars, about the average length of a stay at the ISS. Once they made it there, a crew would have to spend 500 days on the red planet, waiting for the right alignment with Earth before taking off on another six-month return voyage. This is more than leaps and bounds beyond what NASA is currently capable of doing. I can't even imagine how a crew could be trained to perfectly orchestrate a trip of that length.

The panelists who reviewed Constellation had similar feelings. But their reservations were squarely in the financial zone. With infinite resources and time, of course, NASA could achieve the goals of Constellation. But the panel questioned whether they should, when private companies might build a next-generation ferry to the ISS more cheaply and efficiently. Far simpler than landing on the moon and Mars, they said, would be angling for Lagrange points or Martian moons, and studying the moon and Mars via fly-by.

NASA has scheduled Ares I to fly with a crew for the first time in 2015, but the panel expects insufficient funding to delay it another two years. They estimate that NASA is about $59 billion too poor to carry out Constellation. Unless Congress and President Obama agree to fund the difference, this spectacular launch might become a symbol of a dream deferred.

On offer: laws of nature

buzzskyline@gmail.com — Tue, 27 Oct 2009 18:10:35 PDT

http://www.flickr.com/photos/mukumbura/ / CC BY-SA 2.0
Econophysics asks how individual actions give rise to large-scale phenomena.

In yesterday's post I asked why economics doesn't have a few laws of nature that could prevent people from basing decisions on the financial equivalent of a perpetual motion machine. Enter the econophysicists, academics, (usually physicists delving outside the field and not economists borrowing from physics), who want to apply the rigorous mathematical methods of physics to understanding the economy. By modeling the economy as a collection of minor actors, like the molecules of gas, they hope to uncover how individual actions give rise to the emergent, large-scale phenomena that have sweeping effects—the booms and busts that take us by surprise.

The term "econophysics" was coined by Gene Stanley, who trained as a solid-state physicist and directs the Center for Polymer Studies at Boston University. Stanley championed the idea that approaches from physics could bring clarity to phenomena ranging from the flight paths of albatrosses to the patterns of heartbeats. In an article in APS News last year, Stanley talked about how economics needs to face up to important features of the market and the economy that had been brushed under the carpet. Price fluctuations, for instance, are assumed to take on a Gaussian distribution, where extreme events taper off in frequency and are considered rare enough to be ignored. But in reality, sudden drops or leaps do occur and send tremors through the rest of the financial system. Rather than asserting one can safely ignore these events or discount them as outliers, economists need to figure out how and why they occur. They need, he says:

to be eternally skeptical of everything–especially in this case of the practice of calling something that does not agree with a theory an “outlier” or “tsunami.” And, perhaps most importantly, to collect as many data as possible before making any theory to interpret them.

Luckily for would-be econophysicists, data about the economy—price changes, mergers, interest-rate fluctuations—are already painstakingly recorded. Perhaps economists of the future will resemble particle physicists, mining large troves of data for fundamental insights.

Writing in American Scientist, Brian Hayes explores the econophysics-based evidence for one possible fundamental law, popularly expressed in the maxim, "The rich get richer, and the poor get poorer." One team held wealth as a conserved quantity like energy, something that can't be created or destroyed. So how does this quantity become distributed? Economists generally believe that the price of a good is always fair; it is where supply and demand naturally converge. But what if the price of a good isn't entirely fair? A thousand transactions later, and wealth will slowly pile up on one side, either with the buyer or the seller. With toy model worlds laid out in code, econophysicists can play out scenarios like this involving many different actors:

If trading continues long enough, essentially all the wealth winds up in the hands of one person. The yard-sale economy, as formulated in this model, is a winner-take-all lottery. The traders might just as well put all their goods in one big pile, and then roll the dice to decide who keeps it all.

Economists are still largely suspicious of cross-disciplinary academics trying to stake claims on their territory in ways like these; econophysics papers are usually published in physics journals rather than economic ones. But if you think about it, a marriage between physics and economics seems entirely natural. First of all, neither physicists nor economists seem to be able to think without a piece of chalk and a scrap of black board space. Or physicists and economists could bond over their love of specialized jargon, which can get so hairy that the Economist magazine handily maintains an online glossary of the economic buzzwords that get bandied about in the media. Then there's the acronyms, whether for large groups or projects—CERN and the WTO, the LHC and the SEC—or jargon words that have gotten too long. CDO: cadmium oxide thin-film or collateralized debt obligation? Ask the relevant expert to explain either, and they're likely to make your head spin.

But as Daniel Holz at Cosmic Variance puts it, there is "one crucial difference":

...what economists do and say really matters, in an immediate and tangible way. They engage in abstruse arguments about the money supply and the subprime market, but at the end of the day, someone somewhere listens to them, and makes a decision about the interest rate, or whether to bailout a troubled bank. Suddenly, millions of people may be out of work. Trillions of dollars may evaporate. A large fraction of the population of the planet may be affected.

No one saw the current financial crisis coming: a few years ago Ben Bernanke, the chairman of the Federal Reserve Board, gave the economy a clean bill of health and applauded economic policies as salutary. Paul Krugman, a Nobel prize-winning economist, wrote in the New York Times last month:

During the golden years, financial economists came to believe that markets were inherently stable — indeed, that stocks and other assets were always priced just right. There was nothing in the prevailing models suggesting the possibility of the kind of collapse that happened last year. Meanwhile, macroeconomists were divided in their views. But the main division was between those who insisted that free-market economies never go astray and those who believed that economies may stray now and then but that any major deviations from the path of prosperity could and would be corrected by the all-powerful Fed. Neither side was prepared to cope with an economy that went off the rails despite the Fed’s best efforts.

Maybe the failure of classical economics to predict or explain the recent crisis will allow new ways of thinking to get a word in and construct some much-need laws of nature for the so-called dismal science.

Wanted: laws of nature

buzzskyline@gmail.com — Mon, 26 Oct 2009 15:56:16 PDT

Our economy: not a perpetual motion machine.

A physicist friend who worked at the United States patent office once told me that the fastest way for a patent clerk to lose his or her job is to approve an invention that violates the laws of physics. Give a perpetual motion machine the green light, he said, and you'll quickly find yourself holding a pink slip.

Another physicist friend, who about six months ago quit her job at a financial firm, told me that she'd watched with horror as her colleagues fed numbers into a pre-fabricated black box of a model and made decisions based on what it spit out, despite having no idea what went on inside. As a physics student, she was taught to defend answers with rigorous proofs and scrutinize her own ideas for leaps of imagination and faulty thinking. She knew that the worst mistake she could make as a physicist was to fall in love with her solutions. Yet her colleagues comfortably made decisions in intellectual darkness, with far graver consequences than a few missed points on a homework assignment.

Sound familiar? In a New York Times article published in the early part of the economic crisis, David Leonhart wondered how good the good old days really were. Should it be our goal to achieve the fat years we saw before the fall? Or was America just in love with a non-rigorous solution because it told them what they wanted to hear?

The great moderation now seems to have depended—in part—on a huge speculative bubble, first in stocks and then real estate, that hid the economy’s rough edges. Everyone from first-time home buyers to Wall Street chief executives made bets they did not fully understand, and then spent money as if those bets couldn’t go bad. For the past 16 years, American consumers have increased their overall spending every single quarter, which is almost twice as long as any previous streak.

Physics is comfortable with the notion that you can't get something for nothing and that engines can't run with perfect efficiency. When hot coffee cools down, it won't spontaneously warm up again. Loss is part of physics—and life. It's so dependable that a patent clerk doesn't have to think twice about throwing a blueprint for a forever-spinning waterwheel straight into the garbage.

http://www.flickr.com/photos/lindenbaum/ / CC BY-ND 2.0

Businesses are run on the idea that growth must be rapid and continuous. Yet, as one computer scientist put it to me, "As a general rule, when you see something in nature which is increasing exponentially, you know it can't continue for that long. Anything which is really exponential is going to run into a fundamental limit of some kind…and going to hit the limit quite fast."

In familiar economics speak? Bubbles burst. And no, this time isn't different.

Where are the equivalent fundamental laws of economics to provide simple, revealing tests of policies and financial practices? Few economists, if any, second-guessed the Wall Street quants' inventive alchemy that transmuted risky mortgages into fail-safe investments. Fortunes were made and ruined, houses were bought and homes lost, on creative modeling that no one looked at too closely, because no one wanted to. In a part of human life where even "what goes up must come down" is gleefully pooh-poohed, we need a few sobering laws of nature to rein in imaginative thinking and help us take a second look at tantalizingly lovely solutions.

A lease on life for the Tevatron?

buzzskyline@gmail.com — Fri, 23 Oct 2009 16:22:58 PDT

Fermilab's Tevatron, seen from the air.

This just in from Science Insider—2010 may not be the end for big particle physics in America. It looks like Secretary of Energy Steven Chu and the head of the DOE Office of Science, William Brinkman, are fans of keeping big science alive. The Department of Energy is going to ask Congress for money to run the Tevatron at Fermilab in 2011. According to the American Institute of Physics, which has been keeping up with the recent proceedings of the High Energy Physics Advisory Panel:

"We want to keep alive high energy experimentation in the U.S., but need continued strong justification," Brinkman said, adding the science case made to Congress for future research is "not a simple story."

The Fermilab Tevatron, which currently holds the title of world's most powerful particle accelerator, and will do so for as long as the Large Hadron Collider continues to be plagued by troubles, has been given expiration date after expiration date.

Science writer Lizzie Wade visited Fermilab on her Summer of Science road trip to eight national laboratories. She asked one scientists in CDF, one of two collaborations hunting the Higgs with the Tevatron, when he thought this expiration date would finally come around:

He said, "They’ve been talking about turning the Tevatron off since I came here in 1999, so I have no idea."

The two collaborations at the Tevatron, CDF and D0, are racing the LHC (and each other) for the first glimpse of the elusive Higgs boson. While they haven't spotted it yet, they're narrowing down the energy ranges in which it can exist. Earlier this year, D0 announced that they'd measured the mass of the W boson to unprecedented accuracy, allowing them to "squeeze" the Higgs mass into a tighter range of possible values.

The Tevatron has narrowed down where the Higgs can hide.

Until the LHC powers up, the Tevatron is the best tool we have to try to understand the fundamentals of the universe; persistent delays at the LHC make a strong case for keeping the Tevatron alive. Symmetry reports that some graduate students who hoped to pull new physics, and a Ph.D., out of the LHC's operations, have become frustrated with the delays and have migrated to the Tevatron so they can work with real data.

The price for another year of operations at the Tevatron is $20 million. How much is this in the world of politics? A little googling turned up an interesting comparison: in the campaigning leading up to the 2008 presidential primaries, Hillary Clinton racked up $20 million in debt.

Wired ran a story in September on a 79-year-old born-again Arkansan multimillionaire who bought the old site of the Superconducting Super Collider, that late, great disappointment in big American science, with the intention of turning it into a secure data storage facility. Former President Bill Clinton and Congress killed the Superconducting Super Collider in 1993 after the Department of Energy had already sunk $2 billion into warehouses and 15 miles of tunnel in Waxahachie, Texas. Unfortunately, the multimillionaire unexpectedly died a few months after buying the property, the data storage project was abandoned, and the SSC is on sale again—for $20 million.

The Physics Of A Bump In A Rug

buzzskyline@gmail.com — Fri, 23 Oct 2009 15:05:09 PDT

Studying carpet wrinkles is real science.

WASHINGTON -- Scientists often have to make sacrifices for their work. Physicist Dominic Vella chopped his bathroom rug into strips, and L. Mahadevan's coauthor ran off with his bookshelf. With these sacrifices, these two teams were able to glean enough information to revolutionize the world’s understanding about the physics of lumpy carpets.

Dominic Vella's home bath rug, before being sliced up for science.
Image credit: Dominic Vella

Their results, set to be published in two separate papers in the latest issue of Physical Review Letters, describe everything about wrinkles in rugs-- known also as rucks -- including how they form, how they move, and what happens when they interact.

“We were motivated by an old analogy that uses the ruck in a rug to explain how certain defects in a crystal move,” said Mahadevan from Harvard University in Cambridge, Mass. “The phenomenon itself had not been very well studied, and so we decided to spend some time on it.”

The way a bump in a rug travels across a floor has been compared with the way tectonic plates move, cell membranes slide and inchworms crawl. Friction makes it difficult to drag a big piece of carpet, but when there's a wrinkle in the material, the wrinkle can easily roll down the length of the carpet, moving the carpet along in the process.

"It's always used as an analogy for lots of things in physics," said Vella, at the University of Cambridge in the UK, adding that in order to know for sure if these analogies are accurate, "you have to first understand the physics of the ruck in the rug."

Vella's team studied the form that bumps take, how well they hold that shape and how fast they move across a flat surface. First, Vella and his team tested rubber mats of different thicknesses on a variety of flat surfaces. After observing how a wrinkle in the rubber mat developed on wood, sandpaper and metal, the team compared it to the behavior of Vella's own bathroom rug on the same surfaces. To see how these wrinklesmove, the team used a high-speed camera to film the mats while a team member waved one end up and down.

They found that larger wrinkles have an easier time supporting themselves no matter what kind of surface the rug sits on. Smaller bumps smooth out quickly unless there's a lot of friction holding them up from the surface below. For most types of carpet Vella tested, moving bumps travel at around one meter per second, though smaller ones tend to move faster than larger ones. When two wrinkles collide, they combine to forma bigger one that moves even faster.

Mahadevan's team looked at how gravity pulls a bump down a ramp. He placed a wrinkled rubber sheet on the bookshelf borrowed from his office and tilted it until the wrinkle started rolling on its own. He describes in detail the bump's speed, shape, and angles at which different sizes started rolling.

Both teams plan to further explore the new field of carpet mechanics.

Based on the results so far, they confirm, physicists can still use wrinkled rugs for their analogies.

By Mike Lucibella
Inside Science News Service

What's really exciting about research like this is on the one hand it really does have all kinds of important applications for understanding tectonic plates and cell membranes. At the same time, it's got that wonderful touch of wackiness that makes it a perfect contender for the annual Ig Nobel Prizes. Past physics winners have included research on snapping spaghetti, soggy cereal and hula-hoops. L. Mahadevan even has some experience with the Ig Nobels, he won for physics in 2007 for studying wrinkled sheets.

Perimeter Institute opens its doors

buzzskyline@gmail.com — Wed, 21 Oct 2009 15:25:45 PDT

The Perimeter Institute in Ontario, Canada. Photo from the Perimeter Institute web site.

On Monday I posted on the Perimeter Institute in Ontario, a theoretical physics enclave started by the man behind the BlackBerry. From the pristine grounds, geometrical buildings, and ubiquitous blackboards I saw on the campus in my virtual tour, I would have guessed that PI was run as a sort of retreat where theoreticians can work on arcane problems far from the mundane cares of the real world.

I was wrong! And what a time to make such an error! The PI has actually thrown open its doors to the public with the Quantum to Cosmos Festival, presented with Canadian television channel TVO. It's going on right now (October 15-25)—in fact, if you hit their website right this second you might catch the end of Sean B. Carroll's talk on Charles Darwin, streaming live. (Sean B. Carroll is a biologist and author and is not the same person as Sean M. Carroll, astrophysicist. Sean M. gave a talk last week.) I'm posting now to give readers a chance to tune in live, but I'll be back in a moment with more information on the festival.

Update: So it looks like Quantum to Cosmos has already presented several really interesting public talks, which you can now watch online—they've had Sean M. Carroll on the arrow of time, geek-god Neal Stephenson on science fiction as a window into science, and a session melding dance, music, and a lecture by physicist and author Gino Segre all on German "Renaissance man" Wolfgang von Goethe. Woah.

According to the website, the festival celebrates PI's 10th year in existence. I'm sort of surprised—and impressed!—to see a place devoted to wild ideas in physics put on such a huge event for the public. But apparently PI's outreach department has been hard at work on a number of neat projects. They've just debuted Alice and Bob in Wonderland, a series of 60-second-long cartoons in which two kids in a chalkboard world innocently ask questions on everything from why the sky isn't bright at night, since there are stars in every direction, to why we can't walk through walls—atoms are, after all, mostly empty space. The series' willingness to tackle oddball questions, instead of expected ones, is the ethos of PI distilled into cartoon form. Who knows, perhaps the cartoon will slyly influence kids to think outside the box—I love it!

The Perimeter Institute is currently under the direction of Neil Turok, a South African physicist who won a TED award in 2008 for his work promoting the next generation of physicists in Africa by founding the African Institute for Mathematical Sciences, an institute for postgraduate studies. In an interview on TVO, Turok talks about why the Quantum to Cosmos Festival has been hugely popular with the public, growing up with two anti-apartheid activists as parents, some of the physics questions that are keeping him up at night, and "eureka" moments:

Bravo to the Perimeter Institute for committing a good chunk of time, money ,and effort to making physics accessible, interesting, and fun for the public. Anyone make it to Waterloo for this event? What did you think?

Theater for physics fans, and physics for the rest of us

buzzskyline@gmail.com — Wed, 21 Oct 2009 09:33:22 PDT

TONY CENICOLA/NEW YORK TIMES

Three of Tom Stoppard's plays reveal a deep fascination with physics.

When it comes to writing about science, playwright Tom Stoppard is in a genre all his own. Stoppard, whom you might know as the screenwriter for the movies Shakespeare in Love and Brazil, wrote three plays he called his "physics plays": Arcadia (1993), in which a group of modern academics try to piece together the life of a young girl in the early 19th century; Hapgood (1988), about the fictional head of a top British intelligence agency during the Cold War; and Rosencrantz and Guildenstern are Dead (1966), in which Stoppard reimagines Shakespeare's Hamlet from the perspective of its two least important characters. But the plays aren't science fiction or physics edutainment, nor do they portray events from the history of science or depend on science to drive the plot. Instead, Stoppard masterfully uses concepts from physics to ask deep existential questions: who are we? Do we have free will? How do we find meaning in the short span of a lifetime?

Brad Carroll, a professor of physics and chair of the physics department at Weber State University, created an entire course exploring the physics (he assigns a science materials alongside the plays) and philosophy in these three plays. Here's what he had to say about reading Tom Stoppard as a physicist and using his plays to teach physics to students from all disciplines.

How is the course organized?

We start with a physics textbook, Seven Ideas that Shook the Universe. The wonderful thing about this text is that that the order of the ideas as they're presented are just the order that [the students] encounter the ideas in the plays. We talk a little about early Greek astronomy, all the way up to Kepler and Copernicus. Then we do Hamlet and Newton's Laws before Rosencrantz and Guildenstern are Dead. We do thermo, and then do Arcadia, then quantum physics, and Hapgood...I have them put on some of my favorite scenes in the play. It prevents it from turning into strictly a lecture physics course. The scenes are those that have good physics significance.

What kinds of students usually take the class?

It's usually not the physics students who are in there, which I'm happy about—they're going to be showing off that they already know this stuff. We've had English majors, theater majors, philosophy, manufacturing technology, just every part of the spectrum as far as disciplines.

Is it more of a literature course or a physics course?

I think I'm teaching both. I'm probably only qualified to teach one, the physics, but I hope they come out with an appreciation of literature and of how a good play is constructed. I've certainly had a lot of great conversations on the play and on the physics. I give them exams both on physics content and on the content of the plays.

Rosencrantz and Guildenstern are Dead gets right into physics with the opening scene. The two are tossing coins, and they come down heads 87 times in a row.

Yes, and Rosencrantz is not at all surprised by it, but Guildenstern is quite worried. It sets the stage, the suspension of the natural, right at the very beginning. Just like in Hamlet, where the ghost appears right away, the coin flipping is doing the same thing. It's showing that throughout play the laws of probability aren't working, free will isn't working. After all, all their behavior and actions are scripted in play Hamlet.

What about the physics in the movie, which Tom Stoppard directed and includes a lot of impromptu physics "experiments" that the play doesn't have?

Rosencrantz and Guildenstern have such different personalities. Rosencrantz uses inductive logic. He sees things and tries to form a general idea. Guildenstern uses deductive logic. Neither are very good at it.

Rosencrantz sees an apple fall and he starts to get an idea about gravity, but he can't bring it to a general conclusion. Then there's five pots hanging in a row, he moves one back, it smacks the one adjacent to it, and the end flies out—it's a Newton's cradle. He goes to tell Guildenstern about it, lifts the pot and it swings back and hits the pot and breaks, and that lesson is lost.

There's another scene where he nearly invents a steam engine with steam from a steam kettle, but Guildenstern will have nothing to do with it. He also finds that lighter objects and heavier objects drop at the same speed, but when he tries to show this to Guildenstern, he uses a feather as one of the falling objects and of course it doesn't hit the ground at the same time.

There are all sorts of little references to physics in the movie. It just shows the failure of Rosencrantz to be able to complete the train of inferences that would lead to a general observation.

"Syllogism the second: One, probability is a factor which operates Within natural forces. Two, probability is not operating as a factor. Three, we are now within un-, sub- or supernatural forces.

Now, counter to the previous syllogism:...If we postulate, and we just have, that within un-, sub- or supernatural forces the probability is that the law of probability will not operate as a factor, then we must accept that the probability of the first part will not operate as a factor, in which case the law of probability will operate as a factor within un-, sub- or supernatural forces after all; in all probability, that is."

—Guildenstern, pg. 17, Rosencrantz and Guildenstern are Dead by Tom Stoppard.

Also poor Guildenstern just can't see the point of it.

Guildenstern has a syllogism, a series of steps that proves they're not held within "un-, sub- or supernatural forces." But then he realizes he used logic which can't be trusted, because he can prove they are and prove they are not.

Let's move on to Arcadia. What's there in terms of physics?

It all centers on a young girl, Thomasina, who lived back in the early 19th century and who is ahead of her time. She's intuiting ideas about fractals, about chaos theory, about the laws of thermodynamics—she is seeing way ahead of her time.

I remember there's a moment where she asks a question about entropy.
Yes, she asks her tutor, "If you can stir into jam into rice pudding, why can't you unstir it?" She's thinking about the irreversibility of thermodynamics. She also thinks about fractals, complains to her tutor with something like, "God's truth, Septimus, if God can make an equation like a bell, why not a bluebell, and if a bluebell why not a rose?" She's thinking of the fractal nature of physical world.

Finally, can you talk a little about quantum mechanics in Hapgood?

Stoppard does a wonderful job with Hapgood, which is a spy story. [There's one character] whose name is Joseph Kerner. Kerner is not just a double spy, he works for both the KGB and the British Secret Service. He's beyond being a double spy, he works for both sides. He says even he doesn't know which side he's working for. He passes each side's secrets back and forth. But he always tells the truth...Kerner is of course a physicist. He says it's not necessary to know [who he's working for], he just passes information back and forth.

He's like nature; if you talk about, are electrons waves or particles, the electron knows what it is, and always tells the truth.

"We choose to examine a phenomenon which is impossible, absolutely impossible, to explain in any classical way, and which has in it the heart of quantum mechanics. In reality it contains the only mystery ...Any other situation in quantum mechanics, it turns out, can always be explained by saying, 'You remember the case of the experiment with the two holes? It's the same thing.'"

—Richard P. Feynman, Lectures on Physics/The Character of Physical Law, quoted in Tom Stoppard's Hapgood.

When we do experiments with the electron it can behave like a wave or a particle. When people ask Kerner questions, Kerner always answers truthfully, but how those answers are interpreted depends upon who's asking for them. Duality, the wave-particle duality, is a big theme.

Stoppard has another theme for that play, which is that we all, within us, have our own dual natures. Stoppard says each of our characters is the working majority of a dual personality. The other part is there in a submerged state. Each of us have a dual nature...a side we express under certain conditions, a side we express under other conditions.

Why do you think Stoppard has so much physics in his plays?

Stoppard is not a trained physicist. He has no special training there; he studied it on his own. In interviews he's called these his three physics plays. They were something he felt like doing, but I've read other plays of his with a lot of philosophy in them, but perhaps not much physics at all. He says it was a phase he went through.

Is there a general theme for all three plays?

I think the whole arc for my course is the question of free will. How much control do we have over our lives? That's what Stoppard is really exploring, at least in first two, Rosencrantz and Guildenstern are Dead and Arcadia, because he's really interested in determinism and free will. His view of humanity's plight in Rosencrantz and Guildenstern is that we're like characters on the stage reading scripts, passengers on the boat being carried forward, but we're goin to where the boat is going. In Arcadia, Thomasina is trying to understand free will. She is delighted with not being able to unstir her jam because Newton's law says things go forwards and backwards in the same way by same law, but in her view, the laws of thermodynamics are different. There is an arrow to time, a direction to time, and this might throw a wrench into determinism.

Near the end of the course, we read Feynman's lecture on Probability and Uncertainty from "The Character of Physical Law." Feynman concludes that the past does not determine the future, so "the future is unpredictable." The students find that although quantum mechanics does not explain free will, at least quantum mechanics makes it possible to believe in free will. Whether or not we have free will is still a matter of great debate, and the students enjoy voicing their opinions!

Dr. Carroll in action, teaching "Physics in the Plays of Tom Stoppard."

As an astronomer, how did you end up teaching a course on theater?

The Honors Program had been after me personally to teach an honors course for some time. I'd always enjoyed Tom Stoppard's plays, and I had in my mind loosely the idea of doing a course on physics in the plays of Tom Stoppard, but wasn't quite there yet. Rosencrantz and Guildenstern are Dead is classical physics and Hapgood is quantum physics, but I didn't have a bridge in between them. Then I read Arcadia. I remember when I got to the climactic scene of the play, I realized Arcadia said everything that's important to me as a physicist and probably as human being. I knew then I had the course.

Why did Arcadia have such a powerful effect on you?

In the climactic scene of the play, the all-but-last scene...there's a conversation about how everybody's looking for something. One of the characters in the present day, Hannah Jarvis, says the theme: "Comparing what we're looking for misses the point. It's wanting to know that makes us matter."

That resonates so strongly with people in physics and people in a lot of other fields.

Do you think it's difficult to teach students physics by having them read plays?

I think every college has a conceptual physics course that doesn’t require a lot of math, and so I don't think it's that much different. I use the same physics text as when I taught a conceptual physics course. I'm really trying to build a bridge here between the arts and the sciences, to show [students] that what we study in physics can have meaning for their lives. If you're going to talk about questions of philosophy you should really be formed about the physics that might be involved. You could very well be arguing about a world that doesn't exist.

Why do you enjoy teaching this course?

I'll say that this course has given me some of the very best teaching experiences I've had. At the end of the course everyone has to present a project. I don't care what it is, but has to be something that shows they took something from the course and internalized it and made it their own.

I've had people write songs and poetry about free will, I've had people write children's books...just a lot of things. Somebody did country swing dancing, and as they did it, they talked about the constant conversion of energy between potential and kinetic energy...The presentations of those projects have been the best days teaching I've had at Weber State.

Brad Carroll is a professor of physics and the chair of the physics department at Weber State University in Ogden, Utah. He has been teaching "The Physics of Tom Stoppard's Plays" since 1996. Most of his recent effort has gone into co-authoring An Introduction to Modern Astrophysics, now in its second edition.

Building Inspiration

buzzskyline@gmail.com — Mon, 26 Oct 2009 08:51:08 PDT

"Think Pods" at the Scottish Parliament in Edinburgh. http://www.flickr.com/photos/garyjd/ / CC BY-ND 2.0

The new Scottish parliament building was unveiled in 2004, some Scots were far from pleased. Some felt that the building's unusual design wasn't so much playful, creative, or forward-looking as embarrassing.

"It looks like a baboon cage designed by a demented five-year-old," one told me. Some felt the complex's whimsical design insulted to the Scots' newly-minted representational government, which they'd lacked since 1707. Others, with typical Scottish levity, joked that the building's looks suited its inhabitants and purpose.

It's understandable that Edinburgh natives, used to either Georgian pomp or medieval heft, found the Spanish-designed clash of stone, grass, cement, and wood somewhat out of place amid the ancient buildings of Edinburgh's Old Town. Angular slabs of cement echo the nearby crags of Arthur's Seat, Edinburgh's centrally-located hill, and the volcanic upshot of Castle Rock, which pins down the other end of the centuries-old Royal Mile. Pieces of rock embedded in the cement form a mosaic of Scotland's geologic heritage, while occasional bronze plaques quote from Scotland's wealth of bards and poets. The complex's standout feature happen to be what earned the comment about the baboon cages—each Member's office has, in lieu of a window, a sort of window-box shaped like a backwards capital P. According to architect Enric Miralles, these are contemplation spaces, where Members can think and deliberate. I like the term "Think Pods."

Scots may have ambivalent feelings toward their new Parliament, but I love the idea of a building designed with the inhabitants' intellectual activities, rather than their physical movements, as the top priority. Miralles thought the contemplation spaces would encourage sound reasoning and careful consideration.

His ethos echoes another building, this time across the pond, unveiled in 2004 to mixed reactions from the locals—Frank Gehry's Toon-Town-esque Ray and Maria Stata Center for Computer, Information and Intelligence Sciences at MIT. One of the original designs was even called "Orangutang Tree Village."

There was a great feature on the Stata Center in Wired in 2004 chronicling the building's conception and construction as a sort of epic battle: the Geeks versus Frank Gehry.

Gehry and the geeks' handlers wanted a building that would drag the geniuses away from their flickering screens and get them swapping brilliant ideas, mimicking the "trading zone" that had existed near that very spot since the 1940s as Building 20, where the mix of mathematicians, physicists, and engineers spawned computer hacking, Noam Chomsky, BOSE sound systems, and LSD, among other memorable modern marvels. So Gehry designed the center to have 347 lockable offices for a research body of 1000. He left a lot of open space (to the utilitarian researchers' fury), refused to make any two walls parallel to each other, and made labs transparent showrooms instead of windowless dens. (Fearing retribution, perhaps, he also included a fifty-foot-wide sliding chalkboard.)

Researchers burn the 5 a.m. oil at MIT's Stata center, designed by Frank Gehry. http://www.flickr.com/photos/joiseyshowaa/ / CC BY-SA 2.0

In writer Spencer Reiss's words:

The Stata Center is the linchpin of a $1.4 billion bet that space and place actually matter in the production of esoteric knowledge. It's MIT's $280 million ante in support of the idea that the boundaries dividing science into warring tribes are literally antique, and that the mystery of how humans think can be cracked by putting 1,000 hackers and other assorted "intelligence scientists" under one roof

Reiss's feature also points out that the handlers weren't merely interested in making their geeks geekier; they're brand-conscious and PR-savvy. Stata's inner space gets the geeks thinking, cooking up new, hopefully application-friendly, ideas, while the technicolor, asymmetrical facade projects an image to potential investors of a vibrant, creative stronghold. It was an economic investment to attract economic investment. (True to form, when Gehry's creation started leaking a few years after it was finished, MIT made a serious run for Gehry's money via lawsuits.)

MIT's belief that the right building can actually squeeze better ideas from scientists may be a sign that the era of dim, cave-like labs and buildings that seemed to have been ordered pre-fab from a catalog called "Soviet Cement" is nearing its well-deserved end. At SLAC National Accelerator Laboratory, the facade of the main building of the Kavli Institute for Particle Astrophysics and Cosmology is a wall of glass. A physicists looking up from a tough equation or away from his computer screen sees sumptuous golden hills, studded with the occasional silhouette of a scrub oak, and the lonely dish of Stanford's radio observatory. There are no chalkboards, at least not in immediate site—the building's common areas are equipped instead with glass panels and colorful write-and-wipe pens.

Cosmological equations embellish a ravishing Northern California sunset at SLAC's Kavli Institute for Particle Astrophysics and Cosmology. http://www.flickr.com/photos/erikcharlton/ / CC BY 2.0

Scientists often require elaborate laboratories and expensive equipment—laser tables, scanning tunneling microscopes, or even synchrotrons. But for theorists, whom we think of being happy with a pencil, stack of paper, and a garbage can at the three-point line, could architecture and environment be even more influential? Companies and universities try to offer their experimentalists the best facilities money can buy; is the theorists' equivalent an environment that's more think pod than baboon cage?

The Institute for Advanced Study at Princeton kicks it old school, the proverbial ivory tower in the flesh.
http://www.flickr.com/photos/lugri/ / CC BY-NC-ND 2.0

Perhaps unexpectedly, the city of Waterloo, Ontario is emerging as the one of the most exciting places on earth to do theoretical physics. Mike Lazaridus, head of the company that makes the BlackBerry, started the Perimeter Institute from just about nothing. Because there's no affiliation with a university, Perimeter scholars don't trouble with bureaucracy or teaching. From a recent article in Nature News, they sound downright spoiled: the Institute treats them to limos, a sauna, endless pastures of blackboard, plentiful coffee, a complimentary BlackBerry and even free lunch once a week.

Eric Hand writes that the director, Neil Turok believes that "you can increase the odds [of a breakthrough] by packing as much talent as possible into a room, and fuelling everyone with free coffee." The institute continues to aggressively raise funding, and recently announced they've acquired enough to double the institute's research space with a 55,000-square-foot expansion called the Stephen Hawking Centre.

Perimeter Institute founders razed the local hockey rink and built a theoretical physics Think Pod in its place.
http://www.flickr.com/photos/suntom/ / CC BY-NC-SA 2.0

In the Perimeter philosophy, architecture and design make a difference. In contrast to the Stata Center's towers and precariously-angled blocks, the Institute favors clean lines, geometric shapes, nature, and lots of black. The main building's atrium is mostly light and space; a virtual tour reveals a grand piano and a few tasteful leather couches. The on-campus eatery, the Black Hole Bistro, is the anti-cafeteria, serving up seared skate wing, lemon creme brulee, and wild mushroom risotto with a side of wine and floor-to-ceiling blackboards. The designers seem determined to catch creativity wherever it may occur—there's even a blackboard outside in the courtyard.

A Black Hole Loses its Shirt

buzzskyline@gmail.com — Mon, 19 Oct 2009 07:32:08 PDT

Physicists may have found a way to peel away a black hole's inescapable event horizon and look directly into the infinite weirdness that lies in its core. Many physicists including renowned cosmologist Stephen Hawking said this should be impossible, but Ted Jacobson of the University of Maryland thinks he might be on the right track to create the mythic "naked singularity."

What is a Black Hole

Black holes are gravity's greatest triumph. They're formed at the end of most massive stars' lives, after they've exhausted most of their nuclear fuel. The inward pull of gravity starts pulling all of the star's matter down into its center. A vicious cycle starts. As gravity shrinks the size of the star its density increases, amplifying the pull of gravity as it goes, further shrinking the size of the star …etc…etc. Ultimately, the star supernovas in a final blaze of glory, leaving behind a black hole.

Black holes are black because gravity around them pulls so strongly not even light can escape. When an object, say a spaceship, passes a black hole's point of no return, its "event horizon," the spaceship can only fall down towards its center with no hope of escape. So strong is this pull of gravity, even light travelling at 300,000 km per second, isn't moving fast enough to escape the dark maw of the black hole.

What is a Singularity

At the black hole's center is the singularity, a point of infinite density that contains all the black hole's immense mass in a volume smaller than an electron. The word "singularity" does not really do justice describing how truly weird these points are. An infinitesimally small point has, for all intents and purposes, zero volume. However black holes clearly have mass, rather a lot of it in fact. In order to find the density of singularities, we plug in the figures we know into the formula for density.

density = mass/volume

singularity density = (A lot of mass) / (0 volume)

The catch is, it is mathematically impossible to divide by zero. The laws of general relativity break down trying to describe singularity. In essence, physics fails.

How can a Singularity be Clothed

These singularities are at the heart of every black hole, but are so bizarre that many think there must be a "cosmic censorship principle" to keep them hidden behind event horizons, cut off from the sensible universe. Stephen Hawking has long been an advocate of keeping singularities clothed by black holes. In 1991, Hawking wagered there must be such a principle, betting $100 and a shirt ''embroidered with a suitable concessionary message" against Kip Thorne John Preskill. Hawking lost on a technicality in 1997, but still maintains that there must be a rigid cosmic censorship principle.

How can a Singularity be Naked

Jacobson however is looking for ways the break the censorship principle.

"Why should Einstein's equations have these modesty properties that clothe these singularities so that we can't see them," said Jacobson, lead author of the research, "It could be we just haven't looked in the right places for them yet."

Jacobson used computer models to simulate a collision between a spinning black hole and a rapidly rotating star. He found that if the speed and direction of rotation line up exactly right, the two combine to cancel out the force of gravity. The outward centripetal force of the spinning singularity matches gravity's inward pull, stripping away the event horizon exposing the singularity to the universe. Physicists have researched rotating black holes before, but Jacobson is the first to find a way to successfully expose its interior.

Jacobson's model is still incomplete however, and other physicists are looking to take it to the next level. Jacobson did not account for the complex effects of "back reaction" which causes the plummeting star to lose some of its energy to gravitational waves. Scott Hughes at MIT has a computer model that calculates gravitational waves, and plans to plug in Jacobson's scenario.

"I would love to be able to say definitively if the back reaction is enough to change the naked singularity outcome or not," Hughes said, adding also that he thought there was a good chance that the energy lost would prevent exposure of the black hole's center.

Depending on what Hughes finds, Jacobson says it could be possible to correct for any lost energy beforehand, disproving the cosmic censorship hypothesis. If not, then singularities may stay fully clothed forever.

"It's too bad because it would be nice to see a place where our theory [of relativity] breaks down," Jacobson said, "Cosmic censorship is probably the greatest fundamental question about general relativity as a theory."

PC Speed Limit

buzzskyline@gmail.com — Thu, 15 Oct 2009 13:36:45 PDT

Computers speeds can only continue to increase at the current pace for 75 more years, according to physicists who determined nature's limit to making faster processors.

With the speed of computers so regularly seeing dramatic increases in their processing speed, it seems that it shouldn't be too long before the machines become infinitely fast -- except they can't.

A pair of physicists has shown that computers have a speed limit as unbreakable as the speed of light. If processors continue to accelerate as they have in the past, we'll hit the wall of faster processing in less than a century.

Intel co-founder Gordon Moore predicted 40 years ago that manufacturers could double computing speed every two years or so by cramming ever-tinier transistors on a chip. His prediction became known as Moore's Law, and it has held true throughout the evolution of computers -- the fastest processor today beats out a ten-year-old competitor by a factor of about 30.

If components are to continue shrinking, physicists must eventually code bits of information onto ever smaller particles. Smaller means faster in the microelectronic world, but physicists Lev Levitin and Tommaso Toffoli at Boston University in Massachusetts, have slapped a speed limit on computing, no matter how small the components get.

"If we believe in Moore's laW ... then it would take about 75 to 80 years to achieve this quantum limit," Levitin said.

"No system can overcome that limit. It doesn't depend on the physical nature of the system or how it's implemented, what algorithm you use for computation … any choice of hardware and software," Levitin said. "This bound poses an absolute law of nature, just like the speed of light."

Scott Aaronson, an assistant professor of electrical engineering and computer science at the Massachusetts Institute of Technology in Cambridge, thought Levitin's estimate of 75 years extremely optimistic.

Moore's Law, he said, probably won't hold for more than 20 years.

In the early 1980s, Levitin singled out a quantum elementary operation, the most basic task a quantum computer could carry out. In a paper published today in the journal Physical Review Letters, Levitin and Toffoli present an equation for the minimum sliver of time it takes for this elementary operation to occur. This establishes the speed limit for all possible computers.

Using their equation, Levitin and Toffoli calculated that, for every unit of energy, a perfect quantum computer spits out ten quadrillion more operations each second than today's fastest processors.

"It's very important to try to establish a fundamental limit -- how far we can go using these resources," Levitin explained.

The physicists pointed out that technological barriers might slow down Moore's law as we approach this limit. Quantum computers, unlike electrical ones, can't handle "noise" -- a kink in a wire or a change in temperature can cause havoc. Overcoming this weakness to make quantum computing a reality will take time and more research.

As computer components are packed tighter and tighter together, companies are finding that the newer processors are getting hotter sooner than they are getting faster. Hence the recent trend in duo and quad-core processing; rather than build faster processors, manufacturers place them in tandem to keep the heat levels tolerable while computing speeds shoot up. Scientists who need to churn through vast numbers of calculations might one day turn to superconducting computers cooled to drastically frigid temperatures. But even with these clever tactics, Levitin and Toffoli said, there's no getting past the fundamental speed limit.

Aaronson called it beautiful that such a limit exists.

"From a theorist's perspective, it's good to know that fundamental limits are there, sort of an absolute ceiling," he said. "You may say it's disappointing that we can't build infinitely fast computers, but as a picture of the world, if you have a theory of physics allows for
infinitely fast computation, there could be a problem with that theory."

Lauren Schenkman
Inside Science News Service

Back from the future: is the Higgs jinxing the LHC?

buzzskyline@gmail.com — Wed, 14 Oct 2009 16:16:00 PDT

Photo by Heidi Schellman, Higgs by Particle Zoo

A science essay in Tuesday's New York Times made big waves in the physics blogosphere. Science essay, you ask? I think the editors decided to use that label as a sort of implicit disclaimer, letting readers know, right up front, to not expect a trim, carefully-researched report of a new scientific breakthrough, something that the author, Dennis Overbye, an MIT-educated science journalism vet and deputy editor of the Times science section, can do with his eyes closed. "The Collider, the Particle, and a Theory About Fate" goes out on a limb—a really long limb—and discusses a fringe idea a couple of theoretical physicists posed to explain why the LHC has been plagued with troubles: the Higgs doesn't want to be found.

To quote Overbye:

A pair of otherwise distinguished physicists have suggested that the hypothesized Higgs boson, which physicists hope to produce with the collider, might be so abhorrent to nature that its creation would ripple backward through time and stop the collider before it could make one, like a time traveler who goes back in time to kill his grandfather.

I'm stumped already. If the Higgs mechanism is correct, if matter gets mass by interacting with the omnipresent Higgs field, the boson already exists. Wouldn't it be the detection, not the creation, that was so abhorrent? But this question aside, the basic idea is that finding the Higgs would be so catastrophic, the equivalent "of the universe being hit by a bus," that the event actually reaches a long finger back down the corridor of time and shorts out a superconducting magnet, or (gulp) prods European politicians into cutting the LHC's funding.

The "otherwise distinguished physicists" in question are Holger Bech Nielsen of the Niels Bohr Institute in Copenhagen, and Masao Ninomiya of the Yukawa Institute for Theoretical Physics in Kyoto, Japan. They're both respected string theorists, which makes them either serious physicists or the usual suspects, depending on your philosophical persuasion. If you'd like to dive right into this, you can read one of the papers on the arXiv.

I'm surprised to see a fringe paper from the arXiv, and the arXiv in general, make it into the New York Times, though it should be clear that Overbye's not reporting on this as breaking news or important research—he lays it out right up top that this is a pretty out-there notion. As a science journalist on the physics beat, Overbye must be a frequent tourist to the arXiv, a place I think of as the gritty black-market of physics research, where publication and revision happens fast and loose, far from the watchful eye of peer reviewers. True, most papers are completely legitimate and later surface in the journals, but the arXiv has its fair share of dark alleys and unsavory inhabitants. I'm surprised that Overbye would want to lead his unsuspecting readers right into this less-than-wholesome place. And while I enjoyed the trip, I think INFN research scientist Tommaso Dorigo, a CDF alum preparing to hunt the Higgs with CMS, is a somewhat more seasoned and able guide. While Overbye playfully presents the idea as "bizzare and revolutionary," Dorigo immediately derides it as "respectable physicists gone crackpotty." (Also, his blog post has about two years on Overbye's article.) He dissects one of Nielsen and Ninomiya's papers nearly paragraph by paragraph until he arrives at this gem:

The experiment proposed in the present article is to give the "foresight", so to speak, a chance of avoiding having to close LHC by some funding or other bad luck accident, as it happened to SSC, by instead playing a game of pulling a card from a well mixed stack about the running of the LHC.

As far as I understand it, the proposal is to officially decide whether to go forward with the LHC based on the result of drawing from a pack of cards. The vast majority of cards would read something like "run the LHC," while a very small fraction would instruct CERN to run the machine at settings too low to find the Higgs, and one would say "shut down LHC." If the highly improbable card were drawn, it would be a sign that something in the future was preventing the LHC from running, an argument to follow the instructions on the card. (I'm assuming they'd have to get the people in charge of the LHC to officially decide to act on the outcome of the game, otherwsie this "foresight" influence just wouldn't happen.) In addition, the physicists argue, playing the card game would be a lot safer than just letting things play out. In the latter case, they say, failure by "natural causes" would be far costlier than implementing this simple game. They add, more ominously, who knows how violently the future discovery of the Higgs would affect the past?

This is about where I get off the Magical Mystery Bus and wave Messrs. Nielsen and Ninomiya goodbye.

The internets seemed to feel largely the same way. The article's comments page alone makes for fascinating reading. A lot of folks on the blogs have been saying that Overbye was wrong to write about this kind of thing, especially in such a mainstream, visible place. At Quantum Diaries, a blogger was quick to call it a "bad week for science journalism," while a Science Blogger bemoaned the "bad publicity" for the LHC and reprimanded Overbye for citing something from the free-for-all arXiv. While I do have to agree with his assertion that the media tends to concentrate on the loopy, romantic, science-fiction-friendly details of a science that has much more to offer,I don't think Overbye have his knuckles rapped for being indulging in a little thought-experiment. He keeps the tone light right through, and the article's final sentence reads like a punchline, coloring the rest of the piece as a sort of intellectual joke, not serious science reporting.

Maybe the bigger oversight, as this ScienceBlogger points out, is not bringing up an equally playful (yet, I find, somewhat more believable) idea based on the multiple universe interpretation of quantum mechanics: if finding the Higgs could somehow, preposterously destroy the universe, the only universes we would experience would be ones where the LHC failed to start up or got its funding unceremoniously slashed, like the doomed SSC.

Really, the LHC should thank Overbye for doing them an extraordinary service— he's provided the crackpots with a—to them—practically water-tight proof that the LHC can't possibly destroy the universe after all.

Star Parties go Presidential

buzzskyline@gmail.com — Tue, 13 Oct 2009 15:28:28 PDT

Last Wednesday, a rather unusual group of people gathered on the White House's south lawn. The crowd included 150 local middle schoolers, the president and first lady, presidential science advisor John Holdren and a handful of rock-star-status astronauts: Sally Ride, Mae Jemison, Buzz Aldrin, NASA Administrator Charles Bolden, and the "Hubble repairman," John Grunsfeld. The occasion? Just a bit of stargazing.

At the star party, which was apparently in celebration of World Space Week and the International Year of Astronomy, President Obama delivered something of a science pep talk to the gathered students, encouraging them to think about what discoveries they wanted to make in their lifetimes. Before sending them off to gaze into 20 telescopes provided by NASA, he introduced two guests who made an impact on astronomy at a tender age.

President Obama views Double-Double in Lyra with young stargazers Lucas Bolyard and Caroline Moore at White House Astronomy Night, October 6, 2009. Credit: White House

Lucas Bolyard, a high school sophomore from West Virginia, made headlines recently by identifying a rare neutron star while sifting through pulsar data from a local radio telescope. When a star collapses in a supernova, the remaining corpse, a neutron star, spins, sending out radiation in a sweeping beam like a lighthouse. When this beam sweeps across earth, radio telescopes see a pulse of radio waves—hence the name. Bolyard's discovery, by contrast, was what is known as a rotating radio transient, a neutron star that sends out intermittent bursts instead of a steady, sweeping beam.

Fourteen-year-old Caroline Moore gained the attention of the astronomical community earlier this year by discovering a supernova that eludes classification, throwing models of star death into question. Here she is on the Rachel Maddow show:

If you're interested in doing a bit of stargazing on your own, why not find a local star party? After all, amateur discoveries in astronomy, unlike in other sciences, aren't uncommon—when something big crashed into Jupiter this summer, the first to spot the earth-sized crater was an amateur astronomer in Australia. Stargazing clubs exist all over the United States, regularly host star parties, and often have websites: here's a list of star parties in October.

Joshua Tree night sky. http://www.flickr.com/photos/hmk/ / CC BY-NC-SA 2.0

My first run-in with a star party happened when I was camping in Joshua Tree National Park in the southern California desert, a place where the air is so clear and free from light-pollution that the night sky is positively brilliant. A couple of friends and I, stuffed with campfire-made chili and anticipating a dessert of smores, were in the process of building a veritable marshmallow furnace when two very annoyed-looking old men, of the bow-legged, bandana-wearing variety, sauntered up to our roaring blaze and cleared their throats.

"Could you put that out?" growled one, flexing his shoulders under his denim vest. My friend paused, looking guilty&mdashhis arms were full of old fence posts that he had been about to toss into the fire.

"We're trying to have a star party here and you're ruining it!" barked the other old man.

We weren't exactly sure what a star party was, but the guys looked like they meant business. Water followed by sand snuffed out our fire. The two mean sauntered off again and joined a group of people huddled around expensive-looking telescopes. Everyone turned around and glared at us.

So if you think you might have an amateur discovery up your sleeve, get in contact with a local stargazing club, find an astronomy "Meetup", or arrange to attend a star party in your area. You'll likely find a host of knowledgeable people happy to share their passion—just try not to interfere with their stargazing.

Imagine Science Film Festival starts this week

buzzskyline@gmail.com — Mon, 12 Oct 2009 18:04:56 PDT

If you're in New York City or within driving distance, you're in for a rare treat this week. Thursday is the opening night of the Imagine Science Film Festival, a two-week-long series of film screenings that celebrate science's artistic side.

This is only the film festival's second year, but it's already attracted the attention of major sponsors. Last year the journal Nature co-sponsored the festival, and this year the American Association for the Advancement of Science, publisher of rival journal Science, has taken the helm. Maybe it's because of the festival's unique approach to the genre of science film.

Unlike what you can expect to see on PBS NOVA or the Discovery Channel, these films aren't out to teach a science lesson. ISFF's founder, Alexis Gambis, says that it's the only science film festival that doesn't take the traditional approach.

"There are a few other science film festivals around the world, but the films they show are mostly documentaries meant for TV. They are very pedagogic," Gambis said in an interview with New Scientist. "We're trying to do something different."

Neil deGrasse Tyson on ISFF from Imagine Science Films on Vimeo.

ISFF looks for films where science inspires the visuals, as in the short art film Magnetic Movie, (which I wrote about in an earlier post), or provides the plot, as in the comedy Chances Are, in which a romantically-uninitiated IT worker must use his knowledge of probability to track down a twenty-dollar bill that bears a cute math geek's phone number. For a better sense of what to expect, take a glance at the program and at some of last year's films, which are available on Vimeo. You can watch several in full, including "The Wormhole," in which a young boy hears his physicist grandmother lecture on wormholes and begins searching for one in order to escape his grim family life, or "In vivid Detail," in which a man's rare perceptive disorder colors a budding romance. Or get a preview of this year's festival with the trailer for In Search of Memory, a feature documentary about Nobel prize-winning neuroscientist Eric Kandel, who will answer questions after the screening.

Gambis himself straddles the genres of science and film; fresh from a Ph.D. program in molecular biology and genetics, he's now at the NYU film school. Before working on the festival festival, Gambis coordinated a film series at Rockefeller University, where he worked on his Ph.D. Called "Portrait of a Scientist," the short film series follows several graduate students and scientists, uncovering the quirks of their daily lives, from what it's really like to wear a lab coat to why a research scientist might find himself chasing pigeons.

Despite having studied science all his life, Gambis says he essentially woke up one day and realized he wanted to make films.

"I started taking film classes and showing up in my lab with cameras," he says. "People looked at me like I was crazy."

Fermi Problem Friday: Leaf It to Me

buzzskyline@gmail.com — Thu, 15 Oct 2009 14:25:13 PDT

Autumn is well underway, and the leaves are beginning to turn in much of the Northern hemisphere. That means the ground will soon be carpeted in layers of brown, yellow and gold leaves.

But when a leaf falls from a tree, and its mass moves from on high to down low, what sort of effect does that have on the motion of the Earth?

More specifically, what happens when all the leaves have fallen from the trees?

Does it matter if all the leaves fall at once rather than gradually over the course of several weeks?

I haven't done any calculations yet, but I'll post my answer on Monday.

-Buzz

***

Solution:

My estimate is that the leaves falling from the trees in the autumn speeds the Earth's rotation by about 1 part in 2,000,000,000,000,000. (About 5*10^-14 percent). That's just in the range of detection by the most accurate atomic clocks.

Of course, it's a VERY rough estimate, and I haven't checked any of my calculations. If you care to run through them, and you're the first to find any given error, I'll send you a prize (probably a sticker or some other cool but worthless thing).

**************************

This is a Fermi problem, so I’m going start with some rough numbers.

A reasonable estimate is that trees’ leaves are typically in a range between 5 and 20 meters off the ground. So simplify things by saying their all 10 meters off the ground before they fall from the trees.

When I gather the leaves in my tiny, 10 square meter yard, they typically fill a bag that weighs about 20 kilograms. But they’re dry when I collect them, as opposed to being full of moisture when on the trees, so the leaves in my yard account for about 50 kilograms of leaves on the trees.

Assume, for simplicity, that the entire world is covered with trees just like mine (don’t worry, we’ll scale it back soon enough), so the Earth is covered in a perfect shell of leaves that weigh

ml=A*50 kg/10 meter^2= (4*pi*R^2)( 50 kg/10 meter^2)

Where the asterisk is a multiplication sign, the '^' symbol means 'to the power of', A is the area of the Earth, R is the radius of the Earth, and ml is the total mass of all the leaves on the Earth.

In the summer, the leaves are h=10 m above the ground, so the moment of inertia of the leaves in the summer is about

I(summer)= (2/3)*ml*(R+h)^2

And in the winter is

I(winter)= (2/3)*ml*(R)^2

So the total inertia of the Earth is

I(total summer)=I(Earth)+I(summer)

In the summer.

And

I(total winter)=I(Earth)+I(winter)

In the winter.

But only 10 percent of the Earth is covered in land, and only the leaves in the northern hemisphere fall off in our autumn. As far as I can tell from traveling around, about a fifth of the northern hemisphere is covered in trees, so the revised calculations are more like

I(total summer)=I(Earth)+I(summer)/(10*2*5) )=I(Earth)+I(summer)/(100)

In the summer.

And

I(total winter)=I(Earth)+I(winter)/(10*2*5) )=I(Earth)+I(winter)/(100)

In the winter.

The change in the total angular momentum from summer to winter is

I(total summer)- I(total winter)

And the percentage change is

100*[I(total summer)- I(total winter)]/ I(total summer)

=100*[ I(Earth)+I(summer)/(100)- I(Earth)-I(winter)/(100)]/ I(Earth)+I(summer)/(100)

=[ I(Earth)+I(summer)- I(Earth)-I(winter)]/ I(Earth)+I(summer)

=[ I(summer)-I(winter)]/[ I(Earth)+I(summer)]

Which is approximately

=[ I(summer)-I(winter)]/I(Earth)

=[ (2/3)*ml*(R+h)^2-(2/3)*ml*(R)^2]/I(Earth)

I(Earth)=(2/5)M*R^2

Where M is the mass of the Earth. I could calculate it, but I’m just gonna Google it instead.

M= 5.9742 × 10^24 kilograms which is roughly = 6 × 10^24 kilograms

Percentage change in the inertia is =(2/3)*ml*[(R+h)^2-(R)^2]/[ (2/5)M*R^2]

=(5/3)*ml*[(R+h)^2-(R)^2]/[ M*R^2]

But the radius of the Earth, R, is about 6x10^6 meters so

ml=A*50 kg/10 meters^2= (4*pi*R^2)( 50 kg/10 meters^2), which is roughly 2.4x10^15 kg

=(5/3)*ml*[(R+h)^2-(R)^2]/[ M*R^2]= (5/3)* 2.4x10^15 kg *[(6x10^6 +10)^2-(6x10^6)^2]/[ 6 × 10^24 kg*6x10^6]

Which is about

=(2*ml*2*R*h)/(M*R^2)=4*ml*h/(M*R)=4*2.4x10^15 kg*10/(6× 10^24*6x10^6)

=10*15*10*10^15/(36*10^30)=1.5*10^18/(3.6*10^31)=.5*10^-13=5*10^-14

So the rotational inertia of the earth should drop by 5*10^-14 %in the fall.

Angular momentum is conserved, so if the angular inertia falls, the angular velocity must rise by the same amount. That means the day shortens by 5*10^-14 %. Which is to say the day is shorter by 1 part in 2,000,000,000,000,000.

Atomic clocks at NIST are half as accurate as this, and should be nearly able to detect an increase in the Earth’s rotation as a result of the leaves falling from the trees in the Northern Hemisphere in autumn. The prototype Cesium fountain clock at NIST is accurate enough to see a change of the order that I calculated, but I imagine I made pretty big errors and am probably off by several orders of magnitude one way or the other.

-Buzz

Lava And The Lamp

buzzskyline@gmail.com — Fri, 09 Oct 2009 10:14:03 PDT

Do lava lamps and actual lava share similar characteristics?

WASHINGTON -- When Imre Jánosi's teenage daughter asked him how her new lava lamp worked, she probably expected a quick explanation. But her innocent question sent Jánosi, a physicist at Loránd Eötvös University in Budapest, on an experimental quest to plumb the physics of the popular novelty toy.

"I wanted to find something, an easy explanation for what happens inside," Jánosi explained. "So I started to check the web and the professional literature, and that was a real surprise. There was practically no useful information, nothing about the physics."

Jánosi knew the basics, of course; a lava lamp operates on the principle of convection. The chamber is filled with water (sometimes mixed with additives) and a wax-like substance. Initially, the wax is denser than the water, and settles at the bottom of the lamp. A light bulb heats up the wax until it's less dense than the surrounding liquid. It then rises to the top, cools, and falls back to the bottom.

But Jánosi considered this to be a vague, hand-waving explanation at best. He wanted to know the details. He also had a scientific motivation; Jánosi works in the von Karman Laboratory of Environmental Flow in Hungary, which uses small-scale experiments to study the behavior of fluids in the atmosphere, oceans, and deep inside the Earth. Teachers and even scientists often compare the lava lamp's undulations to the slow convection in the Earth's mantle, and Jánosi wondered if it was truly a good analogy.

Jánosi and his colleague Balázs Gyüre concocted their own lava lamp recipe. A glass cylinder filled with salt water, a heating pad, and a water-cooled lid served as the lamp. Silicone oil was the perfect lava; it was denser than salt water at room temperature, but less dense than salt water when heated past a critical temperature. After much frustration playing with the ratios of oil to water, they had it: a lab-grade lava lamp.

While blobs form and distend erratically in a commercial lava lamp, Jánosi's flowed like clockwork. The silicon on the bottom heated up until it formed a blob that floated to the top. As it cooled, the blob dropped back to the bottom. The lamp could run for two weeks without stopping, while Jánosi and Gyüre studied its behavior at different temperatures.

Earth's inner mantle consists of hot, flowing rock that circulates extremely slowly, and is often explained by analogy to the flow in a lava lamp. But Jánosi found that there are some key differences. The wax in a lava lamp is more viscous than water, meaning it flows less easily.

However, Jánosi said, "Hot plumes that are rising up in the liquid mantle ... are at least 100 times lower in viscosity than the surroundings."

Secondly, lava lamps contain two separate substances that don’t mix together, while the mantle is a blend of many of different materials.

To help him explain the lava lamp's workings to his daughter, Jánosi's paper will be published in the journal Physical Review E.

But his scientific love affair with the toy is far from over. By tinkering with his lava lamp's ingredients, Jánosi may be able to bottle the mantle's physics. "If we could come up with an analogy for mantle convection ... that would be a great step," he said.

-Lauren Schenkman
Inside Science News Service