Cocktail Party Physics

chamber of secrets

If one more cold or flu virus hits our household before the end of 2009, we might officially place ourselves under quarantine, or opt to live in one of those plastic bubbles to avoid picking up any more pesky illnesses that sap our energy and reduce productivity to the point where taking out the garbage is considered a major achievement. Seriously, I've come down with more colds this past year than in the five previous years combined. Fortunately, Jen-Luc Piquant amuses herself by trolling the Interwebz for cool stuff, and knowing how much I love science-themed art, or art based on science (hell, even science based on art!), she pointed me to a post on Symmetry Breaking, earlier this year that I inexplicably missed, featuring the latest work of artist Roshan Houshmand. Houshmand has created a series of paintings based on the wispy trails left by subatomic particles as they move through bubble chambers.

It's not the first time Symmetry has featured Houshmand. Back in 2007, the magazine published a nice little feature about the Iranian-American artist's work. Although many family members had science-based careers engineers or medical professionals, Houshmand earned degrees in fine art. One year, her uncles were visited her in upstate New York, and she took them to hear string theorist Brian Greene give a public lecture. Greene's talk blew her away, particularly the notion that there might be 11 dimensions to reality. 'Somehow this statement produced a tremendous feeling of relief in me, and allowed me to redefine my perspectives on life," she recalled.

The experience inspired her to spend the next five months immersing herself in physics books. Somewhere in that process of self-education, she came across photographs from bubble chambers, taken in the 1960s and 1970s at Brookhaven National Laboratory and at CERN. She became fascinated by the patterns, the tracks of otherwise invisible subatomic particles traveling through the liquid hydrogen in the chambers, and this inspired to create her series of "Event Paintings," beginning in 2005. "The images are extremely sophisticated and yet there's something so pure and primal about the movement of the forms," she told Symmetry.  

Houshmand starts with the raw printouts of the images and picks those that "speak" to her in some way artistically.  She uses "cold black" paint as a primer (actually a really dark blue), sketches the outlines of the event with chalk, and then colors in that sketch with paints. The result is some truly dazzling works of art, based on the movement of the tiniest building blocks of nature. How cool is that?

Finding ways to make the invisible, visible, is the reason bubble chambers were invented to begin with: scientists were looking for a means of detecting and imaging cosmic rays, first discovered by Victor Hess in 1912 during an ion chamber balloon experiment. Hess was expecting to find a decrease of ionization in the atmosphere with increasing altitude. Instead, he found just the opposite, and concluded there must be radiation entering our atmosphere from space.

Back then, there were no bubble chambers, but there were cloud chambers, invented by Scottish physicist Charles Thomas Rees Wilson in 1895 at Cambridge University's famed Cavendish Laboratory. Wilson was interested in the weather and wanted a means of reproducing the condensation of clouds in the laboratory. This happens as the result of a sudden expansion of the volume of some closed vessel filled with air saturated with water vapor. Said expansion causes a drop in temperature, and makes the air supersaturated, resulting in condensation. And he brought the tools of physics available at that time to bear on the challenge, most notably discharge tubes. He focused on how ions serve as nuclei for water droplets, and even began photographing the formation of those droplets.

By 1910, Wilson had figured out he could use his cloud chamber device to detect charged particles, since they would leave a trail of ions -- and water droplets -- as they passed through the gas in the chamber.  He took the very first photographs of the tracks left by alpha and beta rays, not to mention evidence of how individual atoms and their electrons interacted. Both alpha and beta particles have distinctive tracks: the former is broad and straight, while the latter is thinner and more easily deflected by collisions with other particles. Apply a uniform magnetic field across the cloud chamber, and positively and negatively charged particles will curve in opposite directions. Wilson chambers became all the rage in particle physics, leading to all kinds of exciting discoveries. The discovery of the positron in 1932 at Caltech occurred thanks to a Wilson chamber, garnering physicist Carl Anderson a Nobel Prize in the process. Wilson himself snagged a Nobel, too, for his invention of the cloud chamber.

I love cloud chambers, particularly the one on display at San Francisco's amazing Exploratorium science museum. There's even a handy Website with instructions on building your own. But cloud chambers had their limitations for research purposes, particularly as particle physics continued to advance. They were too small, for one thing, for use at large accelerators. And the liquid filling wasn't sufficiently dense to interact with a large number of highly energetic particles. It also had a slow cycle: the process of reactivating the cloud chamber took too long compared to the accelerator cycles.

Enter Donald Glaser, an American physicist credited with inventing the bubble chamber, which works on similar principles to a cloud chamber, except it is filled with a superheated liquid instead of a gas. The son of a sundries salesman, Glaser hailed from Cleveland, Ohio, and was a sufficiently accomplished musician that he played with the local symphony at age 16. But his real love was math and physics, and he went on to earn his PhD from Caltech in 1950.

Legend has it that while he was on the faculty of the University of Michigan, Glaser was chilling with colleagues over a cold beer, observed the stream of bubbles in his glass, and was inspired to build a device that could track subatomic particles with bubbles. Glaser himself later refuted this story; beer was not his inspiration, although he did use it as a liquid in early prototypes. His first device was a small glass bulb roughly the size of his thumb and initially filled not just with beer, but also soda water and ginger ale. He didn't have much success with those liquids at capturing the trail of bubbles left by subatomic particles. Then he built a small bubble chamber in 1953 filled with superheated liquid diethyl ether, augmented with a high-speed camera to record the very first tracks of cosmic rays. He won the 1960 Nobel Prize in physics for his achievement -- one of the youngest scientists to be so honored.

Today's bubble chambers are filled with, say, superheated hydrogen. Yes, hydrogen is normally a gas but if you keep it under pressure it will take the form of a liquid. Then you can release it ever so slightly at the moment particles enter the chamber, so that it becomes superheated. This happens because the energetic particles make the liquid boil as they pass through the chamber, creating a trail of bubbles in their wake. It's tough to detect the particles themselves, since they're gone within nanoseconds, but the bubbles expand on the order of microseconds -- enough time for photographs to be taken from multiple angles by a set of cameras, thereby giving scientists a 3D image of the particle's path. Then you just re-pressurize the chamber, and you're ready to detect the next batch of particles.

Glaser experimented with superheated liquid hydrogen, as well as xenon gas, after moving to the University of California, Berkeley, further refining his invention. In his first two years at Berkeley alone, he collecting nearly half a million photographs tracking the passage of particles through a newer, bigger bubble chamber built by his colleague, Luis Alvarez. This device was six feet long, compared to the inch-long bubble chamber Glaser first invented, and it could measure particle tracks every 14 seconds. Chalk up yet another Nobel Prize, this time for Alvarez, whose machine helped launch the era of big science in high-energy physics.

Ironically, both Alvarez and Glaser left particle physics after their triumphs. Some have speculated they became bored and a bit disillusioned with how automated the field had become. These days, it's all about trolling through massive amounts of data with supercomputers, hoping to find the telltale signature of a rare exotic particle. Everything is digitized, and modern detectors can record hundreds or thousands of particle bursts in just a few seconds. I think modern particle physicists still find plenty of excitement, creativity and innovation in their work -- it might be more automated, but creating and detecting a top quark isn't exactly as easy as a factory assembly line. But from the perspective of a man schooled in the craft of tabletop physics experiments, it was the end of an era.

Glaser went on to make his mark in the field of molecular biology, researching the evolution of bacteria, how cell growth is regulated, and the causes of cancer and genetic mutation. In particular, he found that certain mutations in Chinese hamsters caused the animals to be unusually sensitive to UV light; exposure to UV rays caused the mutated cells to turn into cancer cells. The same defects can be found in humans, giving rise to a rare cancer called xeroderma pigmentosum. (It's a kind of vampire cancer, in that if the sufferer avoids exposure to daylight, they can remain cancer free.)

He co-founded the first biotechnology company with two colleagues in the 1970s, correctly foreseeing the explosion in applying the fruits of molecular biology research to industry, particularly medicine and agriculture. And when even that lost its novelty, Glaser moved into neurobiology, specifically studying the human visual system and its perception of motion and depth. Glaser also used photo-analyzing equipment he'd originally developed for his bubble chamber to identify species of bacteria via computer scanning, so he brought a bit of automation to his new field as well. And while bubble chambers have been largely superseded in particle physics by later technologies such as spark chambers and wire chambers, they are experiencing some resurgence of interest in the ongoing search for dark matter particles.

All in all, it's been a richly rewarding and varied life for the man who build the first bubble chamber, even discounting the glories of a Nobel Prize. How many physicists can say their inventions have inspired artists to create paintings based on those inventions?

get the lead in

I recall reading an article asserting that women living in the same house or dorm would end up with synchronized menstrual cycles.  I'm thinking that women who blog together must have some universal rhythm too, since I started working on a "lead post" a week ago - well before Lee posted hers yesterday.  Luckily, lead is a dense enough topic that the only overlap between our posts is the Romans.

My inspiration wasn't a half-nekkid HughJackman (see Lee's post), although that is an inspirational vision.  I was trying to find out whether L'Oreal sponsored programming on PBS, as I'm looking for a funding source for a program I'd like to do on cosmetics.  What came up on Ask.com was a paper from Nanoletters by a group of researchers from L'Oreal R&D (in France) about nanoparticles of lead sulfide (PbS) used by the ancient Greeks and Romans for dying hair black.

Lead has been a cosmetics component for a very long time.  Lead white (lead carbonate or 2PbCO₃·Pb(OH)₂ + PbCO₃) was used for foundation by the Hellenes, which is pretty impressive because it takes a lot of chemical synthesis.  Pliny the Elder described how to prepare it from metallic lead and vinegar in a paper in a very early edition of JACS.  The Volos museum in Greece has power compacts from the end of the 4th Century B.C.  Lead white also used to be common in paints, but (as Lee points out), it poses a risk of lead poisoning.  The Romans just used talc and gypsum - as did I the one time my husband and I tried drywalling. 

The natural look is in now, thankfully, but it surprised me that the many of the Greco-Roman recipes are still being used.  Mix lead oxide (PbO) with slaked lime (Ca (OH)₂) and a small amount of water.  The resulting paste applied to gray or light-colored hair and, after 24-72 hours, turns the hair black.  Grecian formula is lead (II) acetate (Pb(CH₃COO)₂) and it works the same way as the ancient formula.  (Just for Men hair coloring does not use lead acetate - but it doesn't work as gradually as Grecian formula.  Or so I'm told.)

The protein alpha-keratin makes up most of your hair (as well as your fingernails).  (Beta keratin makes up harder things, like bird beaks, reptile claws and scales). Keratin is a long coiled molecule that acts like a spring, as shown in yellow in the picture at left.  Four keratin springs twist together to form a protofibril.  Eleven protofibrils twist together to form a microfibril, which is the largest structure shown in the diagram at left.  Keratins have lots of the sulfur-containing amino acid cysteine and that allows the formation of disulfide bridges that hold together keratin molecules.  Think of a disulfide bridge as two keratin molecules holding hands.  The bridge forms a much stronger structure than the two individual molecules.  Sulfur bridges do the same thing in vulcanized rubber.

Microfibrils pack together in long thin bundles called macrofibrils.  Macrofibrils pack together to form long thin cortical cells, and cortical cells pack together to form a hair. Human hair is about 14% cysteine and most of it is in the grey area in the figure that separates macrofibrils.  There is a fair amount of sulfur in hair, which is why burning hair is one of the absolute worst smells in the world - even when it is someone else's hair.  Permanent curling and straightening products break sulfur bridges, reshape the hair, and then reform the bridges so that the hair adapts the new shape.To give you an idea of size, the average hair is about 70,000 nanometers.  A macrofibril is roughly 7 nanometers in diameter. L'Oreal has a great animation showing the composition of the hair. The picture at right (from the L'Oreal animation) shows the macrofibrils (the smallest structures visible in that shot) and the cortical cells that make up a hair.

The little black things you see within each macrofibril is melanin, which is responsible for giving you your hair color.  Large star-shaped cells called melanocytes reside at the bottom of the hair follicle and manufacture the melanin, which is incorporated into the hair structure as the hair is formed. Only about 1% of the hair is melanin, so it doesn't take much to give it its color.

There are only two types of melanin.  Eumelanin is rice-shaped and comes in brown and black varieties. Phaeomelanin is irregularly shaped and imparts a pink to red hue. Japanese hair contains mostly eumelanin and red hair is rich is phaeomelanin.  Black eumelanin is in mostly non-Europeans, while brown eumelanin is in mostly young Europeans.  A small amount of brown eumelanin in the absence of other pigments makes hair blond.  A small amount of black eumelanin without other pigments causes grey hair. With no melanin, hair is white, although we don't know yet whether that is because your body stops producing melanin, or if it just isn't incorporated into the hair.

When the coloring formula interacts with the hair, the lead in the colorant combines with the sulfur in the hair and forms nanoparticles of lead sulfide (PbS) with diameters between 4 nanometers and 15 nanometers.  In contrast, natural melanin that produces black hair is about 300 nanometers in diameter.  The longer you leave the formula on the hair, the more nanocrystals you form and the blacker the hair looks.  This is why coloring products like Grecian formula slowly change the hair color and can get rid of grey gradually, unlike permanent color.  The PbS nanocrystals are very small and it doesn't take a lot of them to change the apparent color of the hair, so the mechanical properties of the hair aren't really affected.

Why do they form nanocrystals and not microcrystals?  One theory is that peptides - polymers that surround the organized keratin proteins - form nanoreactors that limit the size of the PbS nanoparticles.  The nanoparticles accumulate preferentially at the boundaries between the microfibrils, whereas melanin colorants are randomly distributed throughout the hair.

L'Oreal presents the L'Oreal-UNESCO awards each year to outstanding women scientists across the world:  one in African/Arab countries, one in Europe, one in North America, one in Asia, and one in Latin America.  The awards recognize the important role science plays in their industry and in the rest of the world.  They also offer a variety of awards and fellowships for women at other stages in their careers.. because we're worth it.

dance dance (your) ph.d.

Jules Feiffer used to draw cartoons for the Village Voice, back before it, too, sold out to the man, and every now and then he'd throw in an interpretive dance cartoon like the animated one that opens his website. The caption would read something like, "A dance to bowling" and a leggy, Giacometti-like woman would spin her way across the panels, inevitably ending in some kind of disastrous tangle. The subject of this post reminds me somewhat of those cartoons. I hardly know what category to put it in. Biomimicry? Fifteen Minutes? Communicating Science? Just how do you label an interpretive dance of your Ph.D. research? I guess "How cool is that?" works.

Dance, of course, has its own physics in its turns and leaps (one that Jennifer has covered in some of her writing about the physics of the fight in her Buffyverse book), but representing physics, or any kind of science, in dance is a whole different matter. This isn't the first collaboration of its kind, however. In 2004-5, Britain's Institute of Physics worked with the Rambert Dance Co. to create "'Constant Speed,' a ground-breaking physical interpretation of scientific principles," commissioned for Einstein Year. This year's first World Science Festival, held here in New York, featured Armitage Gone! Dance's "The Elegant Universe," inspired by Brian Greene's book of the same name.

Gonzolabs, the people who thought up the 2009 AAAS Science Dance Contest, are also pretty sure that "the human body is an excellent medium for communicating science—perhaps not as data-rich as a peer-reviewed article, but far more exciting." Let's test that hypothesis.

Behold, samples from  "Taking Science to the Dance and Back Again," in which graduate students, post-docs, and professors dance their Ph.D.:

In true Jules Feiffer mode, we have Jolene Chang's "The Mechanism of Agrin's Function in Interneuronal Synaptogenesis":

For the more physics minded, there's also a hot "physics tango" of "Single Molecule Measurements of Protelomerase TelK-DNA Complexes"; an interpretive dance of "Generating Entanglement in a Cold Atomic Ensemble via Atom-Light Interaction in an Optical Resonator"; "Understanding turbulence to use magnetically confined fusion" and more. Here's one of my favorites, "The Effects of Climatic Variability and Land Cover Change on Aquatic Ecosystems, Carbon Cycling, and Ecosystem Services of the Amazon River Basin":

Explanations of the dances can be found on YouTube by clicking on "more info" to the right of the video. Gonzolabs has links to all the videos. The winners, BTW, will have their research professionally choreographed and presented as "This is Science" at the 2009 AAAS meeting in Chicago. Gonzolab's adds that "the goal of this contest is to bring scientists and artists together in a successful collaboration. The output--"THIS IS SCIENCE"--will continue to develop with the aim of a full theatrical run and, hopefully, a world tour."

How cool is that, indeed?

H/T to Dr. Glam.

a spark in the dark

One wouldn't expect the 17th century English philosopher Francis Bacon to have much of a sweet tooth; he always struck me as a rather curmudgeonly sort, thoughts firmly fixed on Higher Matters, eschewing the paltry comforts of the flesh. But Jen-Luc Piquant suspects he might have had a secret fondness for hard candies, based on a passing remark Bacon made in his treatise, Novum Organum (published in 1620): "It is almost certain that all sugar, whether refined or raw, provided only it be somewhat hard, sparkles when broken or scraped with a knife in the dark."

Now, one could argue that Bacon was merely being an observant scientist following his natural curiosity, but stop and think for a moment under what conditions he might have discovered such an effect -- alone in a darkened room with a bag of hard candy and a knife to break up the pieces into smaller bits that were easier to consume. Sounds like a secret sweet tooth to me! This also establishes Bacon as the earliest to record the phenomenon, known as triboluminescence, a.k.a., "the Wint-O-Green Life Saver Effect."

I adored Wint-O-Green Life Savers as a child, mostly for the refreshing minty taste, but they also had loads of entertainment value. It's pretty well known that if you chew fresh, dry Wint-O-Green candies in a dark room -- or snap them in two using a pair of pliers -- you'll get a spark of greenish/bluish light. That's triboluminescence. In 1753, one Father Giambattista Beccaria wrote a treatise on "artificial electricity," in which he described how easy it was "to frighten simple people only by chewing lumps of sugar, and, in the meantime, keeping your mouth open, which will appear to them as if full of fire." One bets Beccaria was just a laugh-riot at parties. (Actually, considering the level of superstition at that time, he was fortunate not to be run out of town, or even burned at the stake.) 

By the late 1790s, sugar production began to produce more refined crystals of pure sugar in the shape of a large solid cone. Once transported and sold, the cone would be broken into smaller chunks using a "sugar nip" -- I'm guessing similar to, say, nail clippers or a similar type of pinching device. And of course, when the sugar cone was nipped in a darkened setting, there would be tiny bursts of visible light, and Beccaria's little party trick became less effective -- because everyone knew about it by then. It's not just sugar that shows the effect, either, When a diamond facet is being ground, or the gem is being sawed during the cutting process, the diamond may fluoresce blue or green. Open certain postal envelopes in the dark, or tear a Band-Aid wrapper very quickly, and you might see a brief blue-green glow.

There's actually rather a lot going on here, from a science standpoint. The simplest explanation is that when molecules are crushed or torn asunder, electrons are forced from their atomic fields and start colliding with nitrogen molecules in the air. The collisions cause a transfer of energy from the electrons to the nitrogen molecules, which begin to vibrate (an "excited state"). The nitrogen molecules want to get rid of the excess energy -- I guess the vibrations make them uncomfortable -- so they emit light, usually in the ultraviolet range, but there's usually a small amount of visible light as well.

Or, as Wikipedia succinctly puts it: "electrical fields are created, separating positive and negative charges than then create sparks while trying to reunite." It's rather like a lightning strike, in fact. The effect is usually observed with asymmetrical crystals; when those materials are scratched, crushed or rubbed, the chemical bonds are broken and a small flash of light is emitted. Hence the name triboluminescence from the Greek tribein ("to rub") and the Latin lumen ("light").

The effect is even more pronounced with Wint-O-Green Life Savers because of the flavoring used: wintergreen oil is technically known as methyl salicylate, a fluorescent chemical, which means it absorbs light of a shorter wavelength and then emits it as light of a longer wavelength. So when you crush a Wint-O-Green Life Saver between your teeth, negatively charged electrons break free; the atoms that once were their homes become positively charged, and the free electrons start dashing about in search of a new home. Meanwhile the sugar crystals disintegrate, causing nitrogen molecules from the surrounding air to attach themselves to the surface. The free electrons strike the nitrogen molecules, causing them to emit invisible ultraviolet radiation and a faintly visible glow. The molecules of methyl salicylate (wintergreen oil used for flavoring the candy) absorb the ultraviolet light (shorter wavelength), and then re-emit visible blue-green light (longer wavelength). And you have sparkage.

Most of us would be satisfied with that level of detail in an explanation, but scientists adhere to higher standards. They want to know precisely what is happening atom by individual atom, and preferably even at the smallest subatomic level. That way they can better control physical phenomena, and the more you can control them, the easier it is to exploit such effects in practical applications. That's why researchers at the University of Illinois at Urbana-Champaign began conducting experiments that exploited the effect to shed light -- literally -- on how materials fracture. They published their findings last year in the Journal of the American Chemical Society.

"When you break a pencil, you actually have to have broken chemical bonds," Illinois professor Kenneth Suslick told the New York Times last year. "Yet our understanding of the process is surprisingly poor. I fact, when you look at the quantum mechanics of that, it isn't exactly clear how the breakage occurs." What is clear is that when one breaks a material, invariably this drives chemical reactions. And a reaction like triboluminescence "gives us a spectroscopic probe to see what's going on right at the fracture point," said Suslick.

But triboluminescence, as it naturally occurs, is a very small effect. The Illinois researchers had to figure out some way to amplify the effect in order to glean useful information from the fracture point (a spectral fingerprint, if you will). Suslick and his collaborators filled a test tube with a slurry of small sugar crystals and liquid paraffin, then immersed a vibrating titanium rod into it. This generated ultrasound waves, creating lots of tiny bubbles constantly growing and collapsing in the paraffin (acoustic cavitation). The shock waves caused the sugar crystals to collide, nitrogen and oxygen bubbled through the slurry, and the result was bursts of light 100 to 1000 times brighter than the usual triboluminescence. So far they've found the presence of carbon monoxide, CO2 ions, and other products of combustion, and are now working on determining the chemical reactions taking place during triboluminescence.

Research in this area continues to yield surprising results. Last month, physicists at UCLA announced that unspooling a simple roll of Scotch tape produces sufficient X-rays to make clear images of their fingers. Seth Putterman and several students constructed a device to unspool the 3M brand Scotch adhesive tape at a steady rte of about 1.3 inches per second, and placed it in a vacuum. They measured emitted light and X-rays.

Surprisingly, the tape did not emit X-rays continuously, but in short bursts -- enough energy to produce an X-ray image of a finger in a second. (A dental X-ray takes about one-third of a second.) The next step is to build a device that brings two pieces of tape together, and then rapidly separates them -- at a rate of around 1000 times per second -- using a piezoelectric device. The idea is control the effect, and hopefully miniaturize it for potential applications.

Something similar happens with cloth tape, which displays a glowing line where the end of the tape is being pulled away from the rest of the roll. Putterman's team has found most brands of clear adhesive tape also give off x-rays, albeit with a different spectrum of energies. Duct tape does not, and they haven't gotten around yet to testing masking tape. Apparently you also get triboluminescence when you tear off the piece of tape at the end of a roll of photographic film.

Given Putterman's prior work on things like sonoluminescence, it's not surprising that when asked about potential applications, his thoughts naturally turn to nuclear fusion. The idea is that energy from the breaking adhesive could somehow -- aye, there's the sticking point! -- be directed away from the electrons to heavy hydrogen ions that would be cunningly implanted into the tape. Those ions would accelerate and (hopefully) collide with sufficient force that they could fuse, emitting energy in the process. But fear not, OSHA! Ripping off a piece of Scotch tape is not exposing us to dangerous radiation on a daily basis in the workplace -- unless you happen to work in a vacuum. Air molecules otherwise intercept the X-rays, rendering them harmless pretty quickly.

A more realistic possibility is finding some way to exploit the phenomenon in simple medical devices to destroy tumors with bursts of x-rays. And like the Illinois researchers, Putterman's UCLA group is eying a potential application to detect x-ray emissions from composite materials as they start to fatigue (i.e., become more prone to cracking); current methods, which work very well with metals, don't always reveal weak areas composites in time to prevent a crisis. Since composite materials are increasingly used to build airplanes. I, for one (in a burst of self-interest), would support any new technology capable of telling ground crews whether or not the plane I'm boarding is likely to break into pieces mid-flight, 37,000 feet in the air. Just sayin'...

So, wintergreen-flavored candies and Scotch tape could be potential energy sources in the future -- bet the manufacturers never saw that coming. Science is weird. And in this case, truly stranger than fiction.

into the infrared

It's a lazy Easter Sunday, with no plans other than to lounge around the loft with the Spousal Unit and resident cat, surfing the InterTubes for amusing items -- like this wonderful site detailing fiendish experiments on Peeps -- perhaps pausing now and then to reflect on Life With a Capital "L." Among other things, I was shocked to realize that I am more than halfway through my three-month fellowship at KITP, with only four more "Journal Club" sessions to go. It's been a lot of fun: we've had sessions on "The Art of the Book Deal"; a rousing panel discussion on ongoing tensions between scientists and the media (which the Spousal Unit describes at length here); a brainstorming session on scientists in Hollywood, in which we devised the framework for a physics-centric (or at least science-centric) TV series; and of course, a session on Science Blogging 101, in which I set up a blog for our cat, Clio, on Blogger just to illustrate how easy it is. (If Chad at Uncertain Principles can write a book about conversations with his dog about quantum mechanics, Clio can have her own blog.)

My musings reminded me that I've been meaning to write a post about the infrared photography of Caltech's Tom Prince, who's currently at KITP on sabbatical before heading back to Pasadena to take the helm of the newly funded Keck Institute for Space Studies. We hope it will be abbreviated KISS, making it possibly the best science acronym ever. As a handful of shyer souls beat a hasty exit when I asked if anyone wanted to participate in a practice press conference, Tom graciously volunteered to be the guinea pig during the session on Press Conference Protocol. (I have since learned to give people advance notice and ferret out volunteers beforehand.) He spoke for 10 minutes or so about his hobby -- complete with sample photographs of KITP in the infrared -- and took a few questions from the audience afterward. The photographs are truly stunning. Check this out:

And here's another that captures the nearby beach and big blue sky:

It's tough to pinpoint at first what makes these photographs so striking, but it's related to the properties of near-infrared light -- i.e., light just beyond the visible spectrum (wavelengths between 700 nm to 1200 nm, usually falling around 900 nm). Infrared photography records what the human eye cannot see. Many materials reflect and transmit IR light in a different manner than visible light. So there are elements in IR images that resemble photographic negatives (although these pix are clearly not negatives). Blues, browns and dark greens in shadow appear dark, while reds, whites and greens in sunlight appear light. Take a portrait of your loved one and the skin will have a chalky appearance in the IR image, red lips will be pale, and the eyes will show up as dark spots. Vegetation comes out very bright in IR photographs, while a clear sky appears dark, apart from the occasional white cloud.

Andrew Davidhazy of the Imaging and Photographic Technology Department at the Rochester Institute of Technology explains on his Website that this last effect occurs because of "the high near-infrared transmission characteristics of green chlorophyll and high infrared reflectance of the underlying cellulosic structure of these subjects." Among other things, this can be used in aerial surveys and reconnaissance to distinguish trees and grass from diseased or dead trees or burned grass, since those appear dark in IR photographs. (You do need to use a special filter for IR photography, and special IR film if you're using a traditional camera, since otherwise the infrared effect is masked by the exposure to visible light. And  note that this is not the same thing as thermal imaging: IR photography uses radiation reflected from the subject to form images, whereas thermography uses IR radiation naturally emitted by objects, and requires special IR sensors.)

Ideally, the photographer takes all these effects into consideration when composing a scene or choosing topics. Tom said that he tries to take his photographs on bright sunny days -- very common in Santa Barbara -- because there is more IR light when the sun is bright, making the high-contrast effects that much stronger, although he's gotten some interesting, moodier effects in photographs taken on cloudy days. Other suggestions from IR photographers include taking pictures in a graveyard, because the grass will come out almost completely white, with the dark tombstone seeming to almost float eerily in space. Stone buildings covered in ivy or other creeping vegetation also yield striking, high-contrast IR images. And apparently, if you photograph people wearing sunglasses, it's sometimes possible to see the eyes behind the opaque shades in an IR photograph, because the filters used in the sunglasses don't have any effect on IR light.

Tom is just one among thousands of IR photography enthusiasts around the world, as I discovered when I Googled the term after his talk. My research yielded a rich lode of fascinating details. I already knew that infrared light was discovered by Sir Frederick William Herschel, best known for building killer telescopes in the 18th century and discovering the planet Uranus. In 1800, Herschel took some time away from his telescopic observations to fiddle with a different kind of experiment: passing sunlight through different colored filters. The different colors seemed to pass different amounts of heat, so he took things one step further, and passed sunlight through a glass prism to create the telltale rainbow spectrum of visible light. Then he measured the temperature of each bulb.

Herschel found that not only were all the measured temperatures higher than the controls, but those temperatures increased with each color from the violet to the red part of the spectrum. And when he decided, just for curiosity's sake, to measure the temperature just beyond the red portion of the visible spectrum, it had the highest temperature of all. Herschel attributed the effect to "calorific rays," and subsequent experiments demonstrated that they behaved just like visible light -- not surprising, since what he'd discovered was infrared radiation. It was the first demonstration that there were types of light beyond the visible spectrum.

Infrared radiation spawned not only a host of practical applications, but also an entire field of astronomy. Infrared telescopes can see past the huge amounts of interstellar dust in the cosmos into the very hearts of galaxies. People had figured out how to take infrared photographs as recently as the 19th century, but it wasn't easy. In the early 20th century, however, scientists developed special infrared dye sensitizers to create infrared films, and the use quickly spread from the laboratory into more practical applications. In the late 1920s, for instance, John Logie Baird developed the first working infrared videosystem, Noctovision, which, among other things, made it possible to film nighttime scenes during the day (a technique known as "day for night," or, as Jen-Luc Piquant prefers to phrase it, La Nuit Americaine). Just underexpose the shot a little bit; then a dark sky with bright moon-lit clouds and deep shadows looks pretty much how we'd expect a nighttime scene to appear.

Today, IR photography has found application in the study of plant diseases, revealing changes in pigment or cellular material; in paleobotany; to enhance details of deeply pigmented tissues in photomicrography in the biological sciences; and by the textile industry to detect irregularities in fibers. It is also used quite often in criminal investigations to examine and identify cloth, fibers and hair, and it's become a standard laboratory tool for imaging faded, damaged or altered documents. It makes clear the differentiation between pigments, dyes and inks, so if something has been overwritten, you can sometimes figure out the underlying text using IR imaging techniques. This proved handy in the 1930s, for example, when people wanted to see what lay underneath the blacked-out portions of documents vetted through censors.

Davidhazy has a terrific example of this infrared luminescence (or fluorescence in the infrared) on his Website. Twenty years earlier, a mother had placed a letter to her children in a homemade time capsule and buried it near the cornerstone of their house, intending it to be unearthed and read 20 years into the future. Unfortunately, when he now-grown children did so, much of the ink had washed away because water had seeped into the box. There was residual ink, however, albeit not visible to the human eye. When the letter was illminated with light devoid of IR wavelengths, the residual inks fluoresced in the infrared, and when filtered through an IR transmitting filter placed over the lens of a camera, those emissions were captured on Kodak high-speed infrared film. And the children were able to read their mother's words after all.

The rise of the digital camera is beginning to eclipse the use of actual IR film and traditional cameras. No longer is there any need to fuss with all those chemical and mechanical processes. Instead of focusing reflected incoming light onto a piece of film, a digital camera focuses that light onto a semiconductor device -- either a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) technology -- that records light electronically, converting that light into electrical charges.

The CCD and CMOS chips used in digital cameras are already very sensitive to near infrared, not just visible light, which is why these cameras come equipped with filters to remove the infrared. Tom Prince simply adapted his standard digital camera with an opaque filter that cuts out the visible light and enhances the infrared, for a cost of roughly $250. (He doesn't recommend doing so yourself unless you have easy access to a clean room, as it requires opening the camera and exposing the delicate electronic innards to particles in the environment.) Using such a filter, you can't see the shot through the viewfinder. Tom (and, I assume, other IR photographers) have to compose the shot with the filter off, steady the camera in place, put the filter back on, adjust the focus, and then take the shot. It's a little hit and miss, but as the images featured in this post attest, you can get some genuine stunners.

So what happens when you take a color photograph using an infrared filter? Tom has tried that, too, and it is possible to do so. It's just a bit more work, since you need to take two pictures: one with the IR filter, and immediately after, another regular photograph. They need to be in alignment, too, so most IR hobbyists recommend using a sturdy tripod to hold the camera in place. And don't forget to take both photos with the same aperture settings to ensure consistent depth of field. The two photos can then be merged in Photoshop, where one can modify the color channels directly. Any color image can be broken down into the red, green, and blue channels (which is how color images are created); IR light in that context is just another "channel." Here's one of Tom's color IR photographs:

The overall effect isn't quite so much of an eerie contrast, although one still gets the sense of something being "different" about the photograph. Here's the same scene in standard IR black-and-white, for comparison:

You can see many other examples of infrared photography by several different photographers by browsing this gallery of links, and several examples comparing and contrasting color and B&W IR photographs here. Why not browse a little bit and savor a novel way of looking at the world? It's way cooler than rose-colored glasses.

come firewalk with me

While the Spousal Unit and I were entertaining an out-of-town friend at Takami, (a great new downtown LA rooftop neo-sushi bar) on Friday night, one of our local pals was really getting into the spirit of things at a UCLA Physics Department bash. He allowed himself to be persuaded to walk across a bed of piping hot coals in a demonstration of firewalking. Now that's a committed physics professor! The upshot? As we were downing our second Lotus Blossom martini and savoring the spicy albacore tuna sashimi -- a specialite de la maison -- poor David was being escorted home with badly blistered feet, and spent the rest of the night soaking his very sore soles in cold water. His enterprising students caught the whole thing on video, and thoughtfully posted it on the Internets for your viewing pleasure. (Listen carefully, and you can hear David exclaim at the very end, "This actually hurts...")

I'm sympathetic to his suffering, unlike Jen-Luc Piquant, who revels in the misfortunes of others. (Schadenfreude is her middle name, or it would be, should she ever get it legally changed from the decidedly non-mellifluous "Marie-Evangeliste.") But some obvious questions arose in my mind. First, the UCLA party was supposed to be Tesla-themed, so what the heck does firewalking have to do with that? Tesla played with electricity, not actual fire, although both can burn, and Tesla did like showy demonstrations with a strong possibility of injury. Maybe that was the rationale. Second, and more to the point, shouldn't a guy smart enough to get a PhD in physics know better than to walk across hot coals?

Like many things in life, firewalking is a bit of a misnomer, since people are really walking barefoot over a bed of hot coals instead of actual flames. The earliest known reference to the practice can be found in an Indian story dating to around 1200 BC, but firewalking shows up in cultures all over the world, spanning thousands of years. Not surprisingly, it's often associated with religious rituals (eg, in certain Eastern Orthodox communities in Greece and Bulgaria), or done to demonstrate the mystical powers of, say, Indian fakirs. You'll also find firewalking in Polynesia, among Japanese Taoists and Buddhists, and performed by certain bushmen in the Kalahari desert as part of their healing ceremonies.

In modern-day America, the practice is more crassly commercial. Sometime in the 1970s, an enterprising snake oil salesman motivational author named Tolly Burkan started offering evening firewalking courses to the public, selling it as a kind of New Age way of confronting one's fears and asserting mind over matter, emerging with a stronger sense of empowerment as a result. Or something. Think "Fear to Power" instead of "Will to Power." He's since founded The Firewalking Institute for Research and Education, and describes the practice as "a method of overcoming limiting beliefs, phobias, and fears." But he doesn't claim that anything supernatural or paranormal is necessarily going on, which is smart, because the science behind firewalking has by now been pretty well documented.

David isn't the first scientifically minded sort to engage in firewalking: noted skeptic Mike Shermer has done it, as has Jearl Walker, a former columnist for Scientific American who has performed firewalking and other insane feats in classroom demonstrations, memorably commenting, "There is no classroom demonstration so riveting as one in which the teacher may die." (No doubt David's physics students would agree.) A physics professor in Pittsburgh named David Willey does it all the time, and has arguably done the most in recent years to spread the word about the underlying physics behind safe firewalking.

There's even been the odd scientific study of what's involved, scientifically, in the firewalking phenomenon, beginning with one performed in the mid-1930s by the University of London Council for Psychical Research. That study concluded that the secret of the successful firewalk is as simple as the low thermal conductivity of the burning wood-turned-to-coal, an insulating layer of ash, and the short time of contact between the hot coals and the soles of the feet. Per Willey: "What I believe happens when one walks on fire is that on each step the foot absorbs relatively little heat from the embers that are cooled, because they are poor conductors, that do not have much internal energy to transmit as heat, and further that the layer of cooled charcoal between the foot and the rest of the hot embers insulates them from the coals." (Check out some of the "firewalking" hyperlinks if you want more on the specifics of heat conduction, etc.)

Armed with that kind of background knowledge, it's not surprising David figured he'd try his hand at it. But if firewalking is supposed to be so safe, and un-magical, and rooted in sound science, why did he get blisters all over the soles of his feet? Well, like most scientific experiments, you have to set them up and perform them correctly to replicate successful results; there's not much margin for error. People do get hurt in such stunts; in 2002, about 20 managers with the KFC fast food chain in Australia were treated for firewalking-related burns. (Insert your own lame "fried chickens" joke here.) Guess that whole "mind over matter, confronting your fears, blah, blah, blah" mantra didn't work so well for them.

I wasn't there to witness David's firewalking, so I can only surmise about what might have gone wrong. The most obvious explanation is that David lingered a bit too long in one place while walking over the bed of hot coals. Except I did see the video, and he seemed to be moving across it pretty quickly. (I, personally, would have bolted across. While wearing protective, flame-retardant shoes.) So maybe there was something not quite right with the set-up. It's critical that the coals be allowed to burn down sufficiently so that they are at a relatively comfy 538 degrees Celsius or so (1000 degrees Fahrenheit), preferably with a thin layer of ash over them providing a bit of extra insulation. This process also burns off any excess water content in the coals; any remaining water would increase both the heat capacity and thermal conductivity of the coals. It's equally critical to make sure no bits of metal have found their way into the coals, because metal has very high thermal conductivity.

Perhaps David could have further lessened his risk of injury by dampening his feet beforehand (the so-called "Leidenfrost" effect, in which a thin layer of sweat or water instantly forms an insulating boundary layer of steam when exposed to intense heat). However, per Willey, this probably isn't a major factor. For one thing, it carries an added risk of coals sticking to your feet as you walk -- increasing exposure time and therefore causing the soles to burn more than if you just crossed with dry feet. (Willey prefers firewalking with dry feet, and also places a water-soaked carpet remnant at the end of the walk for immediate cooling.) Maybe it's something as simple as the fact that D. has very thin soles, and/or insufficiently calloused feet.

The upshot is that David put his faith in theory, trusting that it would be borne out by experiment, further bolstered by the knowledge that it had been borne out by experiment in the past (alas, conveniently neglecting to fully consider the numerous occasions when the experiment failed). It's always a sad thing when scientific experiments don't quite work. Consider the following exchange posted on Overheard in New York, which supposedly took place in a physics lab at City College of New York, after a less-than-satisfactory experimental result. A student points to the equipment and asks, "Um, is this broken?"  And the professor (identified as being "Russian") sighs defeatedly, "No. Nothing is broken, except my heart."

For David, it's probably less the intangible pain of a broken heart over a failed experiment, and more the physical discomfort associated with "Yowza, these burn blisters hurt!" Nonetheless, I think he learned a lot from the experience, per his email after I told him I was planning a blog post on firewalking in his honor: "You can tell people that it really hurt, and no creams or sprays helped, not even 30% benzocaine. But ice water worked like a charm." His advice for any aspiring firewalkers? "It's a good idea to hoard Vicodin in advance, which I neglected to do." Heed his words, impressionable young people: David has suffered so you don't have to.

He also had a question of his own, namely, "Why does a burn feel hot even hours after the burn? It must have something to do with swelling, but why would that feel like a burn when other causes of swelling do not?" Good question. If pressed, I'd probably fall back on the first stage of wound healing: inflammation. Blood rushes to the wound site carrying new cells and other useful components for rebuilding tissue, then carries away dead cells, bacteria, and the like. Which in turn makes the wound site feel hot. But it's not the most satisfactory explanation, so commenters should feel free to weigh in with their own thoughts about why this is so. It's not like I've thoroughly consulted WebMD (a.k.a., "The Hypochondriac's Bible") on the subject. (I've been avoiding the site ever since it chastised me for being, like, the millionth person to search the terms "chronic headache" and "brain tumor." Quoth the site (in heavy underlined text): "Most headaches are not an indication of brain tumors." Implied message: "So stop asking us and take some Excedrin already!")

While David is waiting for his feet to heal, and contemplating his own folly while wondering where the firewalking experiment went so horribly wrong, we offer this funky YouTube video of a surfing rats experiment for his amusement. They're call The Radical Rodents, and we think they could give Tyson, the famous Skateboarding Bulldog, a run for his money in the YouTube "Most Downloaded" video awards category. If nothing else, they can take David's mind off the blistering pain. (UPDATE: He can also bask in the glory of being quoted in USA Today.) And once he's mobile again, we'll treat him to Lotus Blossom martinis at Takami, where he can regale the wait staff with tales of his derring-do.

by the sword

We're back! All tanned, rested, and ready to tackle whatever life chooses to hurl our way. It was tough to drag ourselves away from the palm trees, sandy beaches, fruity tropical drinks by the pool, haute cuisine, and luxurious on-site spa, not to mention our own private butler (who seemed disappointed that we didn't need him very much). But the sound of a lonely cat, meowing in the empty Los Angeles apartment, drew us back -- that, and the fact that there were bugs. Big ones, small ones, and (most distressingly) bitey ones. After waking up two mornings in a row with fresh raised welts on my arms, I learned to keep the windows closed, even though I liked listening to the waves crashing on the shore at night.

I have no idea what kind of bug was doing the biting while I was blissfully slumbering, but I'll bet Johanna E.M.H. van Bronswijk of Eindhoven University of Technology in the Netherlands would know. She was honored last week with the 2007 Ig Nobel Biology Prize for her work taking "a census of all the mites, insects, spiders, pseudoscorpions, crustaceans, bacteria, algae, germs and fungi with whom we share our beds each night." Apparently there's a whole teeming ecosystem of insects in Netherland beds, at least the ones van Bronswijk studied. Her research wasn't alone in being, um, honored with an Ig Nobel Prize. For instance, the Chemistry Prize went to Mayu Yamamoto of the International Medical Center of Japan "for developing a way to extract vanillin --vanilla fragrance and flavoring -- from cow dung." A Cambridge ice cream shop called Toscanini's created a new flavor in Yamamoto's honor: "Yum-a-Moto Vanilla Twist." No word on whether the vanilla flavoring was derived from cow dung.

But by far my favorite of this year's Ig Nobel honorees was the Medicine Prize, awarded to Brian Witcombe, a consulting radiologist at Gloucestershire Royal NHS Foundation Trust in England, and Dan Meyer, who heads the Sword Swallowers Association International, based in Antioch, Tennessee. They were honored "for their penetrating medical report, 'Sword Swallowing and Its Side Effects,'" which was published to almost no fanfare last December in the British Medical Journal -- maybe because it was Christmas and people were too busy swallowing Yorkshire pudding and opening prezzies to pay much attention to the findings.

For all its long history, very few published reports exist of related injuries from the practice of shoving sharp steel blades down one's throat -- perhaps there are only a little more than 100 sword swallowers worldwide, out of a population of some 6.6 billion people. So Witcombe set out to explore the various techniques and side effects of sword swallowing, with Meyer's help. Forty-six SSAI members participated in the study, having swallowed a combined 2000 swords over the prior three months. More than half (25) had swallowed more than one, five managed to swallow at least ten swords at a time, and one person achieved the whopping feat of swallowing 16 swords simultaneously.

This sort of thing can't possibly be free of peril. A news release last December reported that Witcombe and Meyer found, "Sword swallowers are more likely to sustain an injury -- such as a perforation of the esophagus -- if they are distracted or are using multiple or unusual swords." Mostly, the respondents suffered from a sore throat (or as they call it, "sword throat," such wags, those guys), generally from the multiple sword stunts, or swallowing odd-shaped blades such as curved sabers rather than straight ones. Lower chest pains were another common complaint -- the only remedy being not swallowing any swords for a few days. Sixteen had suffered some form of intestinal bleeding, and three had undergone surgery to repair injuries to their necks. One lacerated his pharynx, another slashed his esophagus -- he claimed to have been distracted by a misbehaving macaw on his shoulder -- and one unfortunate belly dancer suffered a major hemorrhage when three blades lodged in her esophagus unexpectedly "scissored," after an appreciative bystander shoved some dollar bills in her belt. His donation didn't come close to covering her medical expenses, which came close to $70,000. Not surprisingly, most sword swallowers have higher than average health care and medical costs. All it takes it one tiny slip-up, after all.

These injuries are quite real, and quite serious, because unlike many other sideshow novelty acts, sword swallowing is not a magician's illusion -- although there is a trick to it (more on that later). As the x-ray at left attests, sword swallowers really do maneuver that sharp metal blade down the hatch, past all kinds of vital organs. (You can see a really cool in-real-time x-ray here, and watch Meyer do his thing here and here -- at the latter link, he swallows seven swords at once! My throat hurts just thinking about it.)

Sword swallowing is an ancient art dating back to India before 2000 B.C., where it was used primarily as "a demonstration of divine union and power," per Wikipedia. Modern-day Indian fakirs still perform such feats, along with eating burning coals, swallowing snakes, and stopping their own pulse or raising their body temperatures through sheer will -- although not all such feats are genuine; many are illusions.

The art spread to China in the 8th century, then to Japan, where it found a home in Sangaku, that nation's acrobatic theater. It also found its way to Greece and Rome, and finally into Europe in the early Middle Ages, where it became a fixture of street performers. It languished a bit during the Dark Ages, in part thanks to persecution from the Inquisition, resurged briefly in the early 1800s, and then died out again as people lost interest in street theater. But a featured exhibition of sword swallowing at the 1893 World Columbian Exposition in Chicago brought sword swallowing mania to America, where a whole new generation of performers emerged, making some fascinating innovations along the way: multiple swords, bayonets, hot swords, and glowing neon tubes, among other feats. Meyer is one of the best-known contemporary sword swallowers.

It takes practice, sometimes over many years, to develop sufficient skill for safe (relatively speaking) sword swallowing. The term is a bit of a misnomer, since swallowing is actually the last thing you want to do with a sharp blade, since it involves contraction of numerous muscles; instead, the idea is to completely relax the throat and turn it into one long "living scabbard." Essentially, sword swallowers have to figure out how to carefully align a sword with their upper esophageal sphincter -- a ring of muscle at the top end of the throat-- and straighten the pharynx, commonly achieved by hyper-extending the neck by tipping the head waaay back.

The practitioner must then move his tongue out of the way and consciously relax his throat as he "swallows" -- not an easy thing to do because of our involuntary gag reflex, the body's defense mechanism against swallowing foreign objects. Basically, there are nerve endings lining the back of the throat that can detect any intrusive, non-chewed-food objects, generating nerve impulses which neurons carry to the brain stem. The brain responds by using motor neurons to instruct the throat muscles to contract. The end result: you retch, sometimes vomiting, as the body attempts to force the unwanted object out of the throat and mouth.

On the way down, the sword straightens out the curve of the esophagus and nudges certain organs out of the way. Per the book Bizarre Medical Abnormalities, published in 1897:

"The instrument enters the mouth and pharynx, then the esophagus, traverses the cardiac end of the stomach, and enters the latter as far as the antrum of the pylorus, the small cul de sac of the stomach. In their normal state in the adult these organs are not in a straight line, but are so placed by the passage of the sword. In the first place they head is thrown back, so that the mouth is in the direction of the esophagus, the curves of which disappear or become less as the sword proceeds; the angle that the esophagus makes with the stomach is obliterated, and finally the stomach is distended in the vertical diameter and its internal curve disappears, thus permitting the blade to traverse the greater diameter of the stomach."

The same book also notes that sword swallowers proved vital to studying the human digestive system in the 19th century. Specifically, a Scottish physicist named Stevens had an assistant sword swallower down small metal tubes with holes in them, filled with pieces of meat. After a set interval of time, the acrobat would "disgorge" the tubes, and Stevens could study how much the meat had been digested. Also, in 1868, a sword swallower visited Freiburg, Germany, so impressing a local doctor named Keller that he examined the man's throat with a laryngeal mirror. His colleague, one Dr. Muller, is credited with first suggesting that such acrobats would make terrific subjects for esophagoscopy, because of their ability to voluntarily relax all the muscles in the throat at the same time. Another colleague, Adolph Kussmaul, actually performed the first successful esophagoscopy on the visiting sword swallower using a rudimentary endoscope (basically a straight tube), mirrors, and a gas lamp for illumination. The results were a bit disappointing because of the poor illumination, but it did lead to further improvements in the technique.

A famous sword and snake swallower of the mid-1800s, called Sallementro, claimed he learned his art at 17 from a friend; it took him three months. He tried starting with full-sized swords, but discovered "it made my swallow sore, very sore, and I used lemon and sugar to cure it." Apparently he was unable to eat anything, and subsisted on a liquid diet for two months until he'd mastered the trick. Knives, he found, were easier than swords because of the shorter length.  "It was tight at first, and I kept pushing it down further and further." He recommended resisting the urge to cough (duh), and also oiled the blade to reduce the abrasion as it slides down the throat.

Snakes proved less tricky, although Sallementro was careful to "cut the stingers out, 'cos it might hurt you." He used 18-inch serpents, cleaned by scraping them with a cloth because otherwise the things tasted nasty. Unlike swords, snakes are quite helpful to the process, naturally inclined to seek out a dark hole down which to disappear -- unless the swallower coughs too much, in which case the snake seeks to escape back up the hatch. Sallementro said that  swallowing snakes "tickles a little, but it don't make you want to retch." Speak for yourself, buddy.

Like Sallementro, Witcombe and Meyer's study found that many of the respondents had desensitized their gag reflex by starting with smaller objects and increasing the size over time. They started with their own fingers, then upgraded to spoons, paint brushes, knitting needles, bent wire coat hangers, and so forth, before attempting short knife blades and, finally, swords. Per Cecil Adams of Straight Dope fame, I learned that Dan Mannix, a retired carnival sword and flame swallower, wrote a memoir of his experiences in 1951, and reported that he definitely threw up the first few times he tried to overcome the involuntary gag reflex. Then he struggled with getting a sword down his throat because he couldn't... quite... relax. (Hmmm. Wonder why?) Eventually he succeeded, but said that he had to bend forward a bit halfway through the sword's passage to get it past his Adam's apple. He also occasionally struck his own breast bone with the sword, which apparently felt like a blow to the solar plexus, from the inside.

Many have emulated Sallementro and figured out that lubricating the blades with saliva or butter made it easier to slide them down their throats, although one admitted to retiring from the sport after developing a chronic "dry mouth" condition. The sides of the swords aren't sharp, but the tips are, as those who suffered ruptured stomachs (with the resulting peritonitis) can attest. Adams -- recognizing that there's always someone stupid enough to try this sort of thing at home, despite cautionary words -- recommends wiping the blade before and after swallowing: the first, to remove any dust which could trigger the gag reflex, and afterwards to remove stomach acid, which could corrode the blade's metal. (Neon tubes, by the way, have an added risk of shattering inside the throat, with seriously disabling and sometimes fatal effects.)

The gag reflex is also an impediment to aspiring competitive eaters, sometimes called "gurgitators." (Here's a video clip on the topic.) Back when I lived in New York City, every fourth of July, on Coney Island, Nathan's held its annual hot dog eating contest, which garnered a good share of TV coverage. Maybe it was a fascination with the sight of all those people stuffing hot dogs in their faces in such a short span of time, because for five years' running, the outcome was almost a given. The winner all five of those years was Takeru Kobayashi, an internationally renowned gurgitator who holds the world record for eating hot dogs: 53-3/4 hot dogs with buns,consumed in a mere 12 minutes. That's a staggering 12,500 calories in a single sitting. Compare that to the USDA recommended caloric intake for an adult male: 2300 calories. Kobayashi won the event from 2001 to 2006, only being deposed this past summer by some guy named Joey Chestnut. But there are lots of other eating competitions held all over the world every year, many of them sponsored by the International Federation of Competitive Eating (IFOCE).

Gurgitators have some specific strategies, such as dipping contest food in a glass of water, thereby softening and lubricating it so it does down that much easier -- similar to how some sword swallowers lubricate their blades before swallowing. It's also advisable to break food into smaller pieces before eating it, so you can fit more in your mouth and cut down on chewing time. Kobayashi breaks a hot dog in half and stuffs both halves into his mouth at once (buns are always eaten separately). But ultimately, the best competitive eaters seem to have an innate ability -- if such is the word -- for over-eating, thanks to suppression of the gag reflex, better stomach elasticity, and (more mysteriously), suppressing the usual signals the stomach sends out to indicate it is full.

Like sword swallowers, competitive eaters are able to relax all the muscles that line the esophagus simultaneously, turning it into a hollow pipe. Another key is stomach elasticity: it's not the size of someone's stomach, but how much it can expand in order to adapt to the huge amount of food coming in. So gurgitators often "train" by chugging gallons of water in a short period of time to stretch the stomach, or eat huge amounts of cabbage (low-calorie, high-fiber) because it stays in the stomach longer before breaking down. Thats also why fatter isn't necessarily better. The prevailing theory is that excess fat pushes against the stomach and limits how much it can expand. So the best competitive eaters tend to be on the thinner side. It shouldn't be surprising that, as with sword swallowing, there are inherent dangers to competitive eating: vomiting (which damages the esophagus and tooth enamel from the stomach acids that arise), heartburn, gas, and high risk of choking, stomach rupture, or swallowing bones, which can injure the intestines. The IFOCE discourages "training," in part because drinking those huge amounts of water can perforate the stomach lining, or lead to a potentially fatal condition known as water intoxication.

When food empties into the small bowel, this triggers a hormonal stimulus telling the brain that it is sated, making it very uncomfortable to continue eating beyond that point -- unless you have a natural (or learned) ability to dampen or block those signals. That seems to be the case with the best competitive eaters, which is why gastrointestinal specialists are interested in studying such people in hopes of applying the new knowledge to combat over-eating and obesity. It could also lead to breakthroughs in treatment for chronic dyspepsia, in which people feel bloated and in pain after eating only a modest meal because something triggers the stomach to send a discomfort signal to the brain prematurely. and it could help with treating more serious compulsive eating disorders, such as that featured in an episode of C.S.I.: a man feels so compelled to eat that he must be kept chained to a chair and watched at all times, because once he starts eating, he is incapable of stopping. One day he escapes, and after placing second at a local eating competition, finds his way to one of the many Vegas casino buffets, and literally eats himself to death: his stomach distends so much that it crushes the rest of his internal organs, and he dies in a back alley -- with, it must be said, a big smile on his face. Sated at last, albeit in death.

I eagerly await an Ig Nobel worthy study of the gastrointestinal effects of competitive eating; it'd be a nice complement to the whole sword swallowing thing. But in the meantime, congrats to physicists Albert Fert and Peter Grunberg for winning this year's bona fide Nobel Prize in Physics for their discovery of the giant magnetoresistance effect -- about which we will be blogging about in the next couple of days.

REPOST: fashionably late to the dating game

[Original posting at the cocktail party is on a brief hiatus, but we are offering a few reruns to tide you over until the new fall season begins October 9. For today's rehashed offering: A recent article on BBC News described using super-powerful x-rays -- specifically, synchrotron radiation -- to peer beneath the skin of ancient manuscripts, something we covered in this post last summer.]

One tries to stay abreast of all the cool science stories wafting about the World Wide Web, but occasionally, to our great chagrin, we miss something that is so, like, utterly crucial. This is one of those days. Jen-Luc Piquant belatedly stumbled across a fascinating news item from June about a Penn State biologist who has drawn on his scientific expertise to develop a new method (based on a similar technique used to study genetic mutations) for dating manuscripts and artwork from several centuries ago. We aren't sure how this tasty tidbit escaped our notice, but it did, despite the Penn State press release and subsequent coverage in such regularly-perused venues as SEED and the Washington Post. Still, it's just too cool not to post something about it, so we prefer to think of this as coming fashionably late to an already hoppin' party.

The hero of today's bibliophilic tale is Blair Hedges, a professor of biology at Penn State University who specializes in evolutionary dynamics, but has a passionate side interest in old prints and maps, particularly from the Renaissance period. In fact, he's spent years scouring the Caribbean in search of ancient maps of the sea's many islands. Many of the maps he acquired were undated, their provenance a subject of much contention among experts. Dating manuscripts is traditionally a tricky business; antiquarians rely on analyzing fonts, type of paper, or printer's watermarks, among other features. 

The problem with such an approach is that it's a bit too subjective and inexact, by scientific standards; sometimes the best even the top experts can do is make educated "guesstimates." Furthermore, truly gifted forgers, like that infamous murderous Mormon, Mark Hoffman (featured in the terrific book, The Poet and the Murderer), can produce convincing forgeries able to fool most experts. Hoffman produced his forged Oath of a Freeman -- a masterpiece in its own right, as forgeries go -- by acquiring old parchment paper from the desired time period, and making his own engraved plates. Even documented provenance can sometimes be cleverly faked.

Hedges decided there should be a better method, and set about developing one -- a research project he funded himself. He compares his new "print-clock" technique to the molecular clock techniques used to time genetic mutations over several generations, a key tool for dating genetic material in his biological research. In the case of book dating, he measured time-related changes (deterioration) in over 2500  Renaissance works, figuring that the changes were simply random errors in the printing devices, akin to the random errors in DNA that give rise to genetic mutation.

First, he took digital photographs of the texts or prints to be studied -- anything from an engraved book jacket, a biblical text, or an illustrated work like a 15th century map. Then he used image-analysis software and standard statistical methodology to analyze those images. The software specifically detects and counts breaks in the lines of woodblock prints, and can measure fading of the etched and engraved lines of copperplate prints. He published his findings in the June 21 issue of the esteemed Proceedings of the Royal Society.

For the method to work, Hedges had to figure out how to calibrate his "print clock." He discovered that the engraved wood blocks and copperplates used for printmaking deteriorate at a clock-like, constant rate over time, irrespective of print runs.  Historians have long known that there are noticeable changes in print quality found in later editions of printed texts, which they have attributed to the wear and tear of the printing process itself, or the number of times an impression was made with a particular block or plate.

In contrast, Hedges says his analysis demonstrates that changes in print quality are caused by aging of the wood and copper materials that make up the plates during storage between print runs. Why is this helpful? Because the deterioration process is a measurable physical characteristic that he likens to the "random radioactive decay of geologic clocks and the random genetic mutations of molecular evolutionary clocks." Specifically, he found that the number of breaks in the lines of images printed from woodblock carvings increased over time, while the image intensity became more pale in copperplate prints. (A line break is a faded line in a drawing that may have been bolder in an earlier edition of the same text.)

To take advantage of this property, Hedges studied images with known print dates made with the same woodblock or copperplate; this gave him a reference point for determining how the line breaks and other print features deteriorated over time. In the case of woodcuts, it was Bordone's Isolario, an atlas with maps of the Caribbean islands. Three editions have known print dates: 1528, 1534, and 1547. Using the print-clock technique, Hedges was able to determine that his undated copy was printed in mid-February of 1565, give or take a year, so it would have been the fourth edition. For the copperplates, Hedges focused on two books of early maps of Jamaica, Cuba, and Hispaniola; one was printed in six editions over five decades, with the first appearing in 1572, while the other had three editions, the first having been run in 1596.

Now Hedges is chomping at the bit to apply his new technique to undated printings of Shakespeare's Hamlet and Romeo and Juliet, as well as undated prints by Rembrandt. And according to David Gants, an expert on early books at the University of New Brunswick in Canada, if Hedges' print-clock method turns out to be equally accurate for dating woodcuts from various times in the period where books were hand-pressed, "it will -- in one stroke -- render antiquated the existing strategies for dating books."

Pretty cool, huh? Nor is this the first time science has come to the aid of antique books and art, or even archaeological finds. All kinds of cutting-edge instrumentation has been brought to bear on such objects, often with fascinating results, from ultraviolet imaging to x-rays and synchrotron radiation. For instance, in 1999, a team of archaeologists from the University of Chicago's Oriental Institute submitted priceless artifacts recovered from a dig in the Amuq Valley in Turkey, to scientists at the Advanced Photon Source (APS) at Argonne National Laboratory for analysis. They wanted to know how certain artifacts had been made, but the only way they knew to do that was to take the relics apart -- something they were understandably loathe to do. But synchrotron radiation can analyze the internal structures of materials down to the atomic level without destroying or damaging them.

The APS is essentially a gigantic x-ray machine, featuring a ring about the size of four football fields. Inside that ring, electrons accelerate to the speed of light along the curved path, emitting electromagnetic radiation (a.k.a. "light") in various wavelengths ranging from x-rays to infrared. Different materials absorb and emit different kinds of light, which can be detected and analyzed to determine which are present in a given object.

Last year, SLAC made international headlines when it announced the results of an analysis of a priceless Archimedes manuscript (see image, above). The original 174-page manuscript described, among other insights, Archimedes' explanations of the pulley, the fulcrum and the lever, as well as his famed "Eureka!" insight into the physics of flotation that turned him into one of the world's earliest streakers. But the original Greek parchment scrolls were erased and re-used twice, once in the 10th century and again in the 12th, and re-inscribed with the text of a prayer book. It was common practice in that time period, but it did irrevocably alter the history of mathematics, since Archimedes' work was largely unknown during the Italian Renaissance as a result. The parchment was so badly damaged -- moldy, with charred edges -- that traditional imaging methods weren't effective for certain pages.

SLAC's Stanford Synchrotron Radiation Laboratory (SSRL) came to the rescue, revealing the long-obscured original text beneath the later inscriptions. It turns out that the inks used in all the relevant time periods contained iron pigment, and the SSRL can measure extremely small concentrations of iron in proteins. The facility's x-ray beam is tuned to the specific energy for iron, which causes the remaining traces of iron ink to fluoresce. This can be detected and rendered into a visible image, in a manner similar to old dot-matrix printers.

That's science for you: nailing down elusive dates for artifacts, making long-invisible inky inscriptionss visible again, and solving a few historical mysteries in the process.  I'm sure we can look forward to even more "Eureka" moments as scientific progress marches on.

fun with primordial ooze

Spending time with my nieces and nephew recently brought back fond memories of -- among other things -- Dr. Seuss, specifically, a tale called Bartholomew and the Oobleck. It's not one of the best-known works (and it's in prose rather than Seuss' trademark rhyming), but I've always liked it. Anyway, Bartholomew is a royal page in the Kingdom of Didd. King Derwin is a bit of a dunderhead who decides he's bored with plain old water-based rain and show, and orders the casting of a magic spell that causes a green sticky substance to rain down from the sky. The stuff was called "oobleck," and as often happens with magic spells, it turned out to be more troublesome than entertaining, gumming up the entire kingdom until the creatively pragmatic Bartholomew figures out how to save the day.

Very few people would associate Dr. Seuss with science, but if you're, say, me, the tale provides the perfect segue into a discussion of Newtonian versus non-Newtonian fluids -- and who wouldn't want to talk about that first thing on a Monday morning? Of course, I mean "Newtonian" as in Sir Isaac Newton, that 17th century stood-on-the-shoulders-of-giants physicist. Towards the end of his life, Newton delineated the properties of what he deemed an "ideal liquid," of which water is the best example. One of those properties is viscosity, loosely defined as how much friction/resistance there is to flow in a given substance. The friction arises because a flowing liquid is essentially a series of layers sliding past one another. The faster one layer slides over another, the more resistance there is, and the slower one layer slides over another, the less resistance there is. Anyone who's ever stuck their arm out of the window of a moving car can attest that there is more air resistance the faster the car is moving (air is technically a fluid).

That's the basic principle.  But the world is not an ideal place, and not all liquids behave like Newton's ideal liquid. In Newton's ideal fluid, the viscosity is largely dependent on temperature and pressure: water will continue to flow -- i.e., act like water -- regardless of other forces acting upon it, such as being stirred or mixed. In a non-Newtonian fluid, the viscosity changes in response to an applied strain or shearing force, thereby straddling the boundary between liquid and solid behavior. Physicists like to call this a "shearing force": stirring a cup of water produces a shearing force, and the water shears to move out of the way. The viscosity remains unchanged. But non-Newtonian fluids like oobleck? Their viscosity changes when a shearing force is applied.

Ketchup, for instance, is a non-Newtonian fluid, which is one reason smacking the bottom of the bottle doesn't make the ketchup come out any faster; in fact, it slows it down, because the application of force increases the viscosity.  Blood, yogurt, gravy, mud, pudding, and thickened pie fillings are other examples. And so is oobleck. They aren't all exactly alike in terms of their behavior, but none of them adhere to Newton's definition of an ideal liquid.

Perhaps you got to play around with a manmade version of oobleck in middle school science class. I didn't, but some of my pals vividly remember doing so, which doesn't speak well for my early science education, although I do recall making something called glurch in chemistry class -- starch, glue and food coloring -- as an experiment in polymerization.

Oobleck is even simpler to make. You combine 2 cups of corn starch with 3 drops of green food coloring and gradually mix in enough water to create a mixture that resembles pancake batter (usually about equal parts starch and water). Ta-da! Your very own oobleck! And just as the Didd-ians discovered, it's a sticky, messy substance. It's also fascinating in its behavior, as this video by a group of Gonzaga University students (who claim they were just bored during spring break and decided to film their kitchen experiment for posterity) aptly demonstrates.

The substance becomes thicker, or more viscous, in response to agitation, compression or other similar applied forces: punch the oobleck, and it hardens into a solid, softening into a fluid again once the energy dissipates. Compress it into a ball and toss it in the air, and it will quickly lose its shape and flatten before it lands. (Side note: non-drop paint exhibits the opposite effect, brushing on easily but become more viscous once it's on the wall. And under rare circumstances, liquid hydrogen and liquid helium can become superfluids, exhibiting zero viscosity at extremely low temperatures.) As the Gonzaga students correctly (albeit blasphemously) note, you can be like Jesus and literally walk across a cornstarch/water mixture, as these Barcelona folks did, filling a pool with the mixture using a concrete mixer truck.  Things get even weirder if you put the mixture into an agitator. No wonder oobleck is such a time-honored favorite on YouTube: you can find even more fun experimental videos here.

Similar shear-thickening fluids are already being used on prototype bullet-proof vests and sporting equipment, because their sensitivity to impact means they can better absorb the energy of a high-velocity projectile or hard impact, while still being flexible enough for wear comfortably. For instance, at the University of Delaware, scientists treated the fabric of Kevlar vests with a shear-thickening fluid (silica particles suspended in polyethylene glycol). Under normal conditions, the molecules of the treated material are weakly bonded and can move around with ease; that's why the material is so flexible. But the shock of any impact -- a hard fall, or incoming bullet -- will cause those chemical bonds to strengthen so the molecules lock into place and the fabric becomes instantly rigid. Once the force from the impact dissipates, the bonds weaken again and the vest becomes flexible again. The US and Canadian skiers in the 2006 Winter Olympics wore a similar form of "smart armor" manufactured by a British company called d3o Labs.

Note that when the Barcelona folks submerge themselves in the oobleck, they wade through it veeerry slooowly. They have to: the faster they move, the more the stuff will resist their movement. It's very similar to how quicksand behaves. If you want to escape quicksand, it's best not to struggle too frenetically, but slowly and patiently work your way to firmer ground. That's because quicksand is also a non-Newtonian fluid, despite being made up of fine grains of sand or silt; when mixed with clay and salt water, it becomes a colloid hydrogel. So quicksand appears solid when it is undisturbed, but even a tiny (like, 1%) change in the stress on it will cause its viscosity to decrease quite suddenly, and the person walking across it will sink into the sand, after which the sand and water mixture will separate to form something akin to a solid. Apparently it's the salt that's the blame for that trapping power

Once you're mired in the stuff, it's very difficult to get out: Wikipedia informs me that the trapped person "must apply sufficient pressure on the compacted sand to re-introduce enough water to liquefy it. The forces required to do this are quite large: to remove a foot from quicksand at a speed of one centimeter per second would require the same amount of force as that needed to lift a medium-sized car." God forbid your entire lower body should be submerged: the necessary force to return the stuff to a more fluid form would be beyond anything you could muster. Maybe a pal could happen by -- hopefully before the tide comes in and drowns you, should you be unfortunate enough to become trapped in Morecambe Bay in England -- and add some water to loosen things up sufficiently for you to break free. In which case, remember to move slowly out of it.

Remember the Lightning Sand in The Princess Bride? That was a form of dry quicksand, which has been been deemed the stuff of legend by scientists for decades, despite reports of people and entire vehicles being swallowed instantly by desert sands-- just like the crashed biplane in The Mummy, which sank into dry quicksand in a matter of minutes, taking the newly deceased Captain Winston Havlock with it. Dry quicksand is basically loose sand whose bulk density has been reduced by blowing air through it, so that it yields more easily to weight or pressure. It might behave like wet quicksand, but there's no water in it; it's purely a granular material. In parts of the Sahara Desert, it's known as fech fech: a very fine powdery sand under a thin crust that acts as a surprise "trap". The ground can collapse quite suddenly beneath a jeep traveling through those areas, making them virtually impassable.

It turns out that those legends of dry quicksand just might be true after all, thanks to work in 2004 by physicist Detlef Lohse and colleagues at the University of Twente in the Netherlands, who managed to create bona fide dry quicksand and reported their findings in Nature. The researchers filled a container with very fine-grained sand. There were holes in the bottom of the container, and the scientists blew air through it, then shut down the stream of air so that the grains rearranged themselves downward to form a loosely packed substance. Then they hung a pingpong ball filled with tiny bronze balls (just so they could vary the weight in repeats of the experiment) from a thin piece of rope, so that the ball was just touching the sandy surface. The rope was burned through, at which point the ball fell into the sand in one sharp movement. And it moved effortlessly through the sand, rather than the sand being able to support its weight via chains of invisible force -- which is how sand normally behaves.

See what a little Dr. Seuss can do when it comes to finding educational yet fun opportunities to talk about science? Science is everywhere. We also had a family brunch at the Space Needle right before I returned to Los Angeles, where my niece Morgan ordered the Lunar Orbiter for dessert. It's pretty much a dish of ice cream, except it's served in a special dish that keeps it chilled over dry ice. When the dessert is brought to the table, the waiter pours hot water onto the dry ice, and voila! Lots of steamy fog spills over the entire table, to the delight of everyone present -- children and adults alike -- resembling a gaseous primordial ooze. (I can remember as a child, our summer neighborhood swim team would sometimes dump a bunch of dry ice in the heated pool at the end of a winning meet to celebrate, causing the water to bubble as well as producing heavy fog effects.)

Should you be at the Space Needle when a youngster orders the Lunar Orbiter in the future, this is your chance to explain the science behind dry ice: namely, the mysterious nature of phase transitions. In this case, dry ice is created in such a way -- by pressurizing carbon dioxide gas and rapidly lowering the temperature -- that the gas freezes directly into a solid, skipping the liquid phase altogether. (Like many serendipitous breakthroughs, it was first observed in 1825 by a French chemist named Charles Thilorier, who was actually investigating something else entirely.) Adding hot water to the very dry ice reverses the process, producing a heavy fog instead of melting into a liquid.

There's tons of online resources for conducting your own experiments with dry ice for those who want to do their own investigating. Just remember to wear gloves when handling the super-cold substance, and if you're creating fog, to do so in a well-ventilated area. The fog is water vapor mixed in with CO2, and the latter is heavy enough to concentrate at toxic levels close to the ground. An entire subplot of C.S.I. rested on this fact: a physics student wants to take revenge on a jock who seduced, then abandoned her, so melts blocks of dry ice, releasing the water vapor and CO2 into his dorm room in hopes that it will make him sick. But she miscalculates: he and the femme-de-la-nuit end up sleeping on the floor, and are killed instead by the toxic vapors. Jen-Luc Piquant urges everyone to use their scientific knowledge for good, but if you're to hell-bent on engaging in a bit of mischief, it's wise to always double check your calculations.

run, baby, run

Shhh! Try to keep it down to a low whisper, will ya? Jen-Luc Piquant is currently lost deep somewhere in the final Harry Potter book, having waited patiently for her turn -- and somehow avoided all the online spoilers in the process, no mean feat by now. (Anyone considering trying to ruin the surprise for her should be forewarned: she is ruthless when wreaking her revenge. When you least expect it, she will emerge out of Cyberspace via your computer monitor, just like the ghoulish Samara in the horror flick The Ring, who comes oozing out of the TV to claim her victims. Better yet, she'll send Oscar the Cat, a.k.a., the Feline Harbinger of Death, to sit and stare at you expectantly with those unblinking almond eyes. Aieee!) While waiting for myself and Future Spouse to finish our respective readings, Jen-Luc perused the biology of Harry Potter (courtesy of the Biology in Science Fiction blog) and re-read Roger Highfield's entertaining The Science of Harry Potter to keep herself in that Rowling frame of mind. 

Certain skeptical types might assume that it is pointless to look for science in a children's fairy tale, but that just demonstrates an overly literal mind or limited imagination, in our humble opinion. It's all a matter of perspective; as Highfield ably demonstrates in his book, quite a bit of cutting-edge modern technology is, in its own way, quite magical -- electronic paper, for example. And just this week, Wired reported that DARPA -- described as "the Pentagon's way-out research arm" -- wants to design a software suite that can help battlefield commanders predict the future. Seriously. They're developing a "digital crystal ball" capable of foretelling how any given military mission will turn out beforehand. Professor Trelawney would be so proud. And maybe Oscar the Cat can help with the divination aspects.

There's been another Oscar in the news this week: Paralympic champion sprinter Oscar Pistorius, a.k.a. "the Blade Runner," a double-amputee since he was a baby in South Africa. Pistorius was born without fibulae in both of his legs, which were amputated halfway between his knees and ankles just before his first birthday. He's always worn prosthetics, taking his first steps on fiberglass pegs, and has always been highly athletic, playing rugby, water polo, tennis, even wrestling before taking up track and field after suffering a serious injury in rugby. He's known for refusing special treatment, even perfectly legal ones, like handicapped parking spaces. He says his motto has always been, "You're not disabled by the disabilities you have, you are able by the abilities you have."

[UPDATE: There's a fascinating post up at my new favorite blog, Neurophilosophy, on the discovery of the 300o-year-old prosthetic foot. Check it out!]

That motto has served him well thus far. Not yet 21, Pistorius has racked up an impressive string of titles, and is the current Paralympic double amputee world record holder in the 100, 200 and 400 meter events. A few weeks ago, he made his international debut against the world's top able-bodied runners by running the 400 meter event at the Norwich Union British Grand Prix in Sheffield, England. He didn't fare very well, given wet conditions; he placed seventh in a field of eight, and was ultimately disqualified for running outside his lane.

Now Pistorius has set his sights on qualifying for the 2008 Summer Olympics in Beijing -- and therein lies the controversy. It's not unprecedented: according to a May 15 article in the New York Times, there have been at least three disabled athletes who have competed in the Summer Olympics: an American gymnast with a wooden leg (George Eyser); a paraplegic archer from New Zealand (Neroli Fairhall); and a legally blind American runner (Marla Runyon, who competed in the 1500 meters at the 2000 Summer Olympics in Sidney). There's never been an amputee competing in an Olympic track and field event; Pistorius wants to be the first.

The sticking point is whether his prosthetics give him an "unfair advantage" over able-bodied athletes. "But the man is a double amputee!" you may well exclaim. I certainly did. Nonetheless, that's the gist of objections, and the International Association of Athletics Federation (IAAF) is still mulling over the issue before deciding whether or not Pistorius can compete. (There's very little question of his qualifying.) They throw around a lot of impressive scientific jargon when discussing his case, talking about measuring the maximum amount of oxygen his body uses in one minute, per kilogram of body weight (known as an athlete's VO2 max), or assessing the mechanical efficiency of his stride using a dizzying array of different techniques, including force plates and 3D kinematics. They've already used high-definition cameras to film his running motion.

Just what's so special about those prosthetics? These days, Pistorius runs on a pair of high-tech prosthetic limbs made out of carbon graphite, called Cheetahs, since the J-shaped design mimics an actual cheetah foot. They make a telltale "snick-snick-snick" sound on the asphalt as he runs -- a sound competitors have come to dread; one fellow runner said he felt like he was "being chased by a giant pair of scissors."  They're also a bit longer than natural limbs, which some believe enable him to cover more ground with every stride -- those naysayers include single-amputee Paralympic athletes Marlon Shirley and Brian Frasure, both of whom were beaten by Pistorius this past May at the Paralympic competition in Athens. (Jen-Luc thinks this sounds a bit like a case of sour grapes.) That's not something Pistorius can help: the Cheetahs must be longer than biological legs, to compensate for their imperfect biomechanics. Also, the design means Pistorius runs pretty much on tiptoe.

In fact, the more I read about the objections, the more it sounds like people are basing their objections on perception rather than solid science. Any cited perceived advantage is easily outweighed by everything else that Pistorius must overcome. The Cheetahs are not without their drawbacks. For instance, Pistorius doesn't experience the lactic acid buildup that plagues able-bodied athletes, but they don't have to contend with the possibility that the carbon in an artificial limb will snap at an inopportune moment, sending Pistorius to the ground in a movement that more closely resembles a skier wiping out on the slope than a runner stumbling.

He's a slow starter, since he needs to exert more energy to get moving out of the starting blocks that his able-bodied competitors; unlike them, his later stage of a race is his strongest and fastest. For that reason, he'll never be as strong in the shorter 100-meter event; he really shines in the longer 400-meter event, because there he has time to find his rhythm after the inevitable shaky start. As the Sheffield competition made clear, if it's raining, he has trouble with traction. And a stiff, strong wind can blow his legs sideways. Most runners lose speed coming out of a turn, but Pistorius might actually gain energy -- the downside is that once the Cheetahs get going, they can be really tough to control.

Most damning of all is what you find when you crunch the numbers of energy return for Pistorius' artificial limbs. The Cheetahs rely on a passive spring to absorb energy as the foot lands, returning energy to propel the next step forward -- pretty much the same biomechanical concept behind how an able-bodied person walks. but the Cheetahs can't generate anywhere near the propelling force of a biological limb: landing on a human foot in a running stride has a 241% energy return, thanks to the contraction of leg muscles, compared to a roughly 82% spring efficiency for a passive prosthetic foot like that on the Cheetahs. So Pistorius actually has to work at least 30% harder than his  able-bodied competitors to compensate for not having the usual collection of muscles, tendons, ligaments, joints and bones -- and all that power must come from his hips, producing a weird, slightly waddling stride as he runs. The field of prosthetics hasn't yet come close to matching Mother Nature's design.

Pistorius has plenty of supporters, not just detractors. Hugh Herr, director of MIT's Biomechatronics Group and himself a double amputee, thinks Pistorius has "a distinct disadvantage" in track and field: "He's just really fast." Robert Gailey, an associate professor in the University of Miami's department of physical therapy, agrees with that assessment: "There is no science that he has an advantage, only that he is competing at a disadvantage," he told the New York Times. Imagine running on stilts: that's essentially what Pistorius is doing. He's just really, really good at it because he's been walking and running on stilts since birth. His handlers are fond of saying that anyone who thinks having carbon-fiber legs will automatically make them a faster sprinter, should have the operation and meet them at the track.

True, he does have an innate advantage over Shirley and Frasure, both of whom still have one natural leg. Mixed leg sprinters aren't as smooth or fast, according to Gailey, because they lose energy to vertical movement by pistoning up and down. Pistorius might waddle a little, "but his gait has a circular smoothness." Short of amputating their other legs, Shirley and Frasure will just have to accept this innate shortcoming, or find some other means of compensation.

Pistorius isn't some futuristic cyborg, just a gifted runner with two artificial limbs. It's easy to confuse the passive prosthetic limbs used by Pistorius with more active models using bionics and robotics. For instance, Herr has developed a computer-controlled robotic ankle giving an amputee a faster and more natural gait, as well as the Rheo Knee, which has a microprocessor and numerous sensors to allow it to adapt to changes in speed, load, and uneven terrain. The motor generates extra power if the user is walking uphill, while downhill, the ankle uses a brake-like device to dissipate some of the energy. The robotic ankle is powered by a rechargeable battery capable of storing sufficient power for a walk of several miles. Similar work on an artificial foot and ankle that can adapt to changing terrains and walking speeds is being done at Northwestern University. (At the very cutting edge is Cyberkinetics in Massachusetts, which implanted 100 electrodes onto the motor cortex of a paralyzed man that enables him to operate a computer or move an artificial arm using just his thoughts. Yikes!)

Despite all the technological bells and whistles, such devices still aren't as strong or powerful as natural limbs, and they don't respond automatically to signals from the brain, because they aren't linked directly to the central nervous system. But someday they might be. In so, then those types of prosthetics conceivably could confer an unfair advantage on a disabled athlete in the not-too-distant, according to Gailey -- which might be why the IAAF is concerned about setting a future precedent. Nobody wants to see track and field turn into the massive global embarrassment that has become this summer's scandal-plagued Tour de France. "If there are no constraints placed on what technology can be used, at some point there will be an advantage," Herr admitted to the New York Times; in fact, that's the ultimate goal of such research.

Pistorius' success is pushing hard against the traditional boundaries separating disabled and able-bodied athletics, and it's raising a lot of questions and making a lot of people uncomfortable in the process. Nor is the issue likely to go away: a single amputee named Jeff Skiba competed in the US indoor track and field championships last year. The IAAF recently amended its competition rules to ban the use of "any technical device that incorporates springs, wheels, or any other element that provides a user with an advantage over an athlete not using such a device." They claim this is not intended to target Pistorius, merely to better define what constitutes therapy versus an enhancement.

Even the head of the organization's medical and anti-doping commission, Juan Manuel Alonso, admitted to the New York Times that "There is no real grounds to say he [Pistorius] should not be allowed to compete" in the Olympics. I say, enough already. Let the man compete. He's had to overcome enough. Don't make him a poster boy for futuristic technology he's not even using. Yet.

ADDENDUM: Cocktail Party Physics will be hosting the next Philosophia Naturalis blog carnival, slated for April August 15th. Jen-Luc Piquant expects to be finished with Harry Potter any moment now, and is quite keen to begin sifting through submissions. So if you've got anything, be sure to send it along to her at [email protected].