Cocktail Party Physics

get your physics phreak on

We certainly hope everyone tuned in for Monday night's special Halloween episode of The Big Bang Theory, that brand-new sitcom featuring a bunch of physics postdocs who discover a hot young blonde woman has moved in across the hall. (Yes, Gordon, you should be watching, if only for the occasional physics in-jokes.) Because we've been excitedly holding this post until the episode aired so as not to spoil the experience for those not lucky enough to have snagged a preview DVD of the episode. Spoilers suck.

The premise of the episode is quite simple: our lovable geek boys are invited to Penny's Halloween party, and while they are initially reluctant to attend -- knowing full well they'll be out of place among her circle of hard-partying Angeleno pals -- they can't pass up a good costume party. There is no prize for best costume, much to Sheldon's disappointment. (Sheldon is the tall skinny theoretical physicist with a serious case of Asperger's.) We can understand his feelings. He totally would have won if we'd been judging.

See, Sheldon showed up as the Doppler Effect. Let's just say it: Best. Costume. Evah. Fun, too: whenever people would ask what he was supposed to be -- "like, a zebra or something?" -- he'd respond by making that telltale Doppler shift sound ("nee-yah-WOO-ahmmm!") and wait, in vain, for someone to guess correctly. Needless to say, most of the guests were all Children Who'd Been Left Behind in the public school system, at least in terms of their science education.

Anyway, we totally loved this episode, and it's inspired us to compile a list of other physics concepts that might make good costumes for the upcoming Halloween holiday. C'mon, it's way better than dressing up as Brangelina (although we loved them in Mr and Mrs Smith; who doesn't have the occasional "Who's your daddy now?" moment?). We haven't quite figured out how, exactly, one might convey some of these concepts in visual form, but that's where you all can help. Feel free to leave your own suggestions in the comments; bonus points for clever obscurity!

* We'll start by dipping into the classics: try dressing as Schroedinger's Cat! Cat costumes are fairly easy to come by, and you can carry around a little vial filled with colored liquid with a label ID-ing it as cyanide or something. Granted, it'll be a bit tricky walking around all night in a constant superposition of states, but imagine how much fun it will be when someone (a.k.a., an "Observer") notices you, asks about your costume (i.e., "makes a measurement"), and you get to demonstrate your collapsing wave function.

* Alternatively, you can take a more classical approach and dress up as Maxwell's Demon. A snazzy impish costume would do the trick, or your standard Red Devil outfit, and you can emblazon Boltzmann's equation for entropy across your chest for good measure. Then wander around the party separating all the guests according to how "hot" or "cold" they are to create the telltale temperature difference, from which it is possible to extract useful Work (with a capital "W").

* If you're looking for something a bit less mainstream, how about dressing up as a Bose-Einstein condensate this Halloween? That's what happens when a cloud of atoms in a gas get so cold -- practically down to Absolute Zero -- that they behave like one giant superatom. I'm not entirely sure how this would work; a bit of creativity is required. But it'd be a great idea for a costume once we've worked the problem. Any ideas?

* Perhaps you're feeling more astrophysical. You could try dressing up as a black hole. Black is the default party color for hipsters, plus, you could go around devouring all the hors d'oevres that cross your event horizon with zero guilt because hey -- gobbling things up is what black holes do!

* If you're part of a couple, there's tons of options. For instance, you and your date can attend the Halloween festivities as a binary star, or, if you prefer to separate and mingle while still remaining, technically, a couple, you can go as a Cooper pair (see last week's post on the anniversary of BCS theory for more information). If you're feeling very ambitious, try coming up with a couple's costume for the classic double-slit experiment. You and your date can dress up as particles of light, and periodically split up whenever you encounter other guests (the "barrier"). Your coordinated outfits should form an interference pattern whenever you recombine on the other side of the room.

* Don't have a date? You can always dress up as an antiparticle, popping out of your social vacuum at random fluctuating intervals and threatening to annihilate  into a burst of energy every time you encounter an attractive guest made of regular matter -- opposites attract, after all. Who knows? Some sassy young regular particle might think mutual annihilation sounds kinda hot, if a bit kinky. It's certainly far preferable to all those lame pick-up lines one usually encounters at parties.

* Finally, you could get a whole big group of pals together and go as various parts of the Standard Model. Could be risky, though, since you just know everyone will want to be the charmed and strange quarks. (We could make jokes about top and bottom here, but that would just be tasteless. Please resist the temptation yourselves and aspire to a higher brand of humor.)

Feel free to suggest other costume ideas. If you've already celebrated Halloween over the weekend, and are looking for at-home activities on the day itself, you can check out this mockumentary on ghosts (h/t: OmniBrain), or use the Cadaver Calculator to figure out how much your dead body is worth (mine is worth $4475). And while you're surfing around the Internet looking for appropriately scary stuff, make yourself a yummy Brain Hemorrhage cocktail: Pour 1 ounce of peach Schnapps into a shot glass, then slowly add 1 teaspoon of Bailey's Irish Cream. Top off the whole thing with 2 drops of Grenadine. Mmmm! Tasty, bloody brains! Happy Halloween!

just an ordinary man

We're a bit late with birthday greetings, but still wanted to weigh in with well wishes as the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity turns 50. It first appeared in a paper published in The Physical Review in July 1957, and is considered one of the most important milestones in 20th century physics. Small wonder that there have been so many honorary conferences organized this year to commemorate the occasion, most recently  an APS-sponsored conference held October 10-13 at the University of Illinois, Urbana-Champaign. Eight Nobel Laureates were on hand to give talks, including both Leon Cooper (the "C") and Robert Schrieffer (the "S"). John Bardeen (the "B") missed the festivities; he died in 1991. The APS presented a bronze plaque marking the old Physics Building at UIUC as a "site of historic significance." And the university chose this occasion to announce its new Institute for Condensed Matter Theory, making it a truly golden anniversary in the field of condensed matter physics.

"What's all the fuss about?" the average non-scientist is probably wondering. Well, back in 1911, a Dutch physicist named Heike Kamerlingh Onnes was studying a variety of materials at ultra-low temperatures (i.e., close to absolute zero). He found that supercooled mercury lost its resistance completely to the flow of electricity and dubbed the phenomenon superconductivity. Later experiments revealed the same effect in tin, lead, and other pure metals. It was truly a momentous experimental discovery, but it lacked a theoretical underpinning. Try as they might, physicists couldn't explain the actual mechanism behind superconductivity.

Things got weirder the more they looked into this mysterious effect. For instance, in 1933, a physicist named Walter Meissner found that superconductors would expel a magnetic field, making it possible to levitate a magnet -- the "Meissner effect." And around 1950, physicists found that mercury isotopes with lower atomic weight became superconducting at a slightly higher temperature -- the "isotope effect." This seemed to suggest that the motion of atoms in a material, and not just the electrons, was involved in superconductivity.

Felix Bloch became so frustrated with the knotty problem that he postulated his own eponymous "Bloch's Theorem: Superconductivity is impossible" -- even though it was clearly possible, since it had been experimentally confirmed again and again, in an ever-growing number of materials. Richard Feynman admitted that he'd "spent an awful lot of time in trying to understand it... I developed an emotional block against the problem of conductivity." In fact, when he first learned about the seminal BCS paper, "I could not bring myself to read it for a long time." It took a lot to stump a scientist of Feynman's caliber, and he wasn't the only big-brained physicist mulling over the problem.

Technically, Bardeen was an electrical engineer by training, at least early on in his career. He was born in Madison, Wisconsin; his father, Charles, as a professor of anatomy and helped found the medical school at the University of Wisconsin, Madison (UWM). His academic brilliance showed up early: in third grade, his parents moved him up into junior high, and he started college at age 15, majoring in engineering at UWM. A bit surprisingly, considering his low-key temperament, he was a frat boy, a member of Zeta Psi. (Wikipedia tells me that he played billiards to raise the membership fees.) Yet he was also a member of the Tau Beta Pi engineering honor society. Maybe fraternities were different in those days. He ended up earning both a BS and a master's degree in his five years at UWM.

Bardeen worked for awhile at Gulf Research Laboratories in Pittsburgh, but quickly became bored with the work, and decided to earn his PhD in mathematical physics from Princeton University and embark on a research career. His thesis work was in solid-state physics, working with Eugene Wigner, among others, giving him experience that would come in handy years later when he found himself at Bell Labs, struggling to invent a working transistor with two colleagues, William Shockley and Walter Brattain. They finally achieved the first point-contact transistor on December 23, 1947. As most everyone knows by now, the transistor revolutionized the electronics industry. We owe our computers, our MP3 players, indeed, the entire online Information Age, to these three men toiling away in a Bell Labs laboratory during the holidays, when everyone else was drinking eggnog and singing Christmas carols.

Global recognition was not long in coming. The morning of November 1, 1956, Bardeen was scrambling eggs for breakfast while listening to the radio. That's how he learned that he'd just been awarded the Nobel Prize in Physics for inventing the transistor, along with Shockley and Brattain. Apparently he dropped the frying pan in his excitement to inform his wife. A few fun behind-the-scenes Nobel factoids: just before the ceremony, Bardeen found his white vest and white tie had turned green in the laundry, and had to borrow replacements from Brattain. The two men were so nervous before receiving their awards that they split a bottle of quinine to settle their stomachs.

By 1951, the University of Illinois had managed to lure Bardeen away from Bell Labs with the promise of letting him research whatever he wanted. When news of the isotope effect appeared, Bardeen turned his attention back to the problem of superconductivity. He didn't crack it right away, but he and his colleague, David Pines, did supply a critical missing piece. They showed that electrons -- which normally show a strong electrostatic repulsion for each other -- nevertheless could have a sort of indirect attraction, namely by creating vibrations among the lattice atoms, and those vibrations could in turn affect other electrons.

The breakthrough began in the mid-1950s, when Bardeen teamed up with Cooper (then a postdoctoral fellow) and Schrieffer, who was still a graduate student. Cooper supplied the "C" part when he figured out that electrons in a superconductor don't behave as if they were individual particles, but as pairs, now known as "Cooper pairs." Apply an electrical voltage to a superconductor, and you'll find that all those Cooper pairs move as a single entity, creating an electrical current. Cut off the voltage, and instead of gradually dissipating, the current will continue to flow indefinitely because the pairs encounter no resistance to their motion. It only works at ultra-low temperatures: the Cooper pairs separate into individual electrons as the material warms up.

Now for the "S" part: Schrieffer had his own breakthrough insight in early 1957 while riding on a NYC subway. (Based on my years in the Big Apple, most subway riders are probably too distracted by the advertisements for local celebrity dermatologist "Doctor Zee," or the presence of an incontinent homeless individual two seats away, to come up with revolutionary breakthroughs in physics, but Schrieffer beat the odds.) You could emulate Wikipedia and say he "figured out how to mathematically describe the enormous collection of Cooper pairs in a superconductor with one single wave function." Or -- if you're like me, and this makes your eyes glaze over in bewilderment -- you can think of it this way: Instead of crystallizing into a lattice like when water turns to ice, at those very low temperatures, the electrons were organizing and condensing into what amounted to a weird state of matter that permitted the free flow of electricity. Schrieffer himself later compared the concept to a popular dance of that time called the Frug, in which dance partners could be separated by other couples on the dance floor, yet still remained a pair. In the same way, the Cooper pairs in a superconducting material were oblivious to other electrons and the lattice, which meant they could move without hindrance.

Schrieffer's insight provided the final piece of the puzzle, causing Bardeen to observe, in his typically quiet manner, "Well, I think we've explained superconductivity" -- probably in much the same tone of voice as one would say, "Well, I guess it's time for lunch." Their theory explained both the isotope effect and the fact that magnetic fields below a certain strength couldn't quite penetrate superconductors. it also explained why the superconducting phenomenon could only be observed at very cold temperatures near absolute zero: any warmer, and the thermal jiggling would break up the Cooper pairs, disrupting their elegantly balanced quantum dance. In short, Bardeen later recalled, "All the hitherto puzzling features of superconductors fitted neatly together like the pieces of a jigsaw puzzle."

And thus it came to pass that Bardeen found himself the recipient of yet another Nobel Prize in physics -- at the time, he was the first person to win twice in the same field. (Marie Curie, Linus Pauling, and Frederick Sanger all won two Nobel Prizes, just not in the same field.) Another fun behind-the-scenes anecdote:  When he won the prize the first time, Bardeen only brought one of three children to the ceremony in Stockholm because his sons were both at Harvard and he was reluctant to interrupt their studies. Sweden's King Gustav IV scolded him for doing so, and Bardeen  solemnly assured the king that the next time he won the Nobel Prize, he would bring his entire family. I'm sure Bardeen never expected to make good on that promise, but when lightning did indeed strike twice for him, he made sure all three of his children attended the second ceremony.

It's a bit astounding that the BCS theory hasn't really been refined that much over the ensuing 50 years. Apparently, they got it right the first time. High-temperature superconductivity, discovered in 1986, remains a bit of a puzzle: the effect still relies on electron pairing, but the BCS theory doesn't quite apply. Still, it's only been 20 years, compared to the 50-year lapse between the original observation of superconductivity in metals and the development of BCS theory to explain it. High-Tc theory still has some wriggle room.

There has been some innovation shedding further light on the inner workings of superconductivity. For instance, last year a University of Arizona physicist named Andrei Lebed caused a few ripples in the physics community with his discovery that strong magnetism changes the basic, intrinsic properties of the flowing electrons -- an "exotic" kind of superconductivity. He's interested in the physical nature of the Cooper pairs. Whereas in the past, they have been treated as behaving like elementary particles, with correspondingly fixed properties. Lebed asserts that, in fact, "[S]uperconducting electron pairs are not unchanged elementary particles, but rather, complex objects with characteristics that depend on the strength of the magnetic field." And in the presence of super-strong magnetic fields, exotic Cooper pairs are created that follow the weird laws of quantum mechanics: the electron pairs are both rotating and non-rotating at the same time. Hmmm. Curiouser and curiouser.

Superfluidity is an extension of BCS theory, in that it describes a state in which liquid, like current in superconductors, can flow without resistance -- it literally has zero viscosity. Furthermore, BCS theory has provided a useful model for physicists working on everything from the behavior of subatomic particles to the inner workings of ultra-dense neutron stars. Too esoteric for you? Superconductivity, which the theory explains, is responsible for such life-altering technologies as MRI, radio telescopes, and superconducting quantum interference devices (SQUIDs) -- the latter used to make very sensitive geologic measurements,, among other things. High-temperature superconductivity is especially promising in power transmission: its ability to send current over longer distances with fewer losses could result in major energy savings, although to date such a system has yet to be implemented.

No wonder Bardeen appeared on LIFE Magazine's list of "100 Most Influential Americans of the Century" in 1990, one year before he died. Yet for all the accolades he received over the course of his stellar career, Bardeen never let that sort of thing go to his head. Almost every colleague, friend and biographer describes Bardeen as a most ordinary man, who didn't behave like the stereotypical "genius" physicist. He liked to golf and go on picnics. He hosted cookouts for friends and family, some of whom weren't even aware of his remarkable scientific accomplishments. What made his impact on physics extraordinary was his gift of pinpointing interesting problems in physics, selecting the right collaborators -- making sure to bring both experimentalists and theorists to the table -- and keeping his eye focused on the ball, worrying away at the problem until he arrived at a likely solution.

Alas, his trademark humility and insistence on bucking the "crazy genius scientist" stereotype meant that "the public and the media often overlooked him," according to University of Illinois historian Lillian Hoddeson, who wrote a book about Bardeen. And that's a shame. So in addition to wishing BCS theory a well-earned golden anniversary, here's to men like John Bardeen -- truly the people's physicist. We reap the benefits of his work every day, even if few of us know his name.

they do it with mirrors

Flipping through channels a couple of weeks ago, in a rare (these days) moment of TV-viewing leisure, I caught Texas Instruments' latest commercial for its Digital Light Processing (DLP) technology. You know the one: an adorable little girl is strolling along with an elephant -- willing suspension of disbelief, people! Work with me! -- holding a very small box. She opens it to reveal a beam of pretty light shining upwards, and the little girl says in awestruck sotto voce: "It's amazing. It's the mirrors."

Most people viewing that commercial probably have only the vaguest idea what it's about, other than describing a key enabling feature of high-definition TV. (They're probably distracted by wondering, "What's with the elephant? Why an elephant?") But TI's Larry Hornbeck must feel a special frisson of satisfaction every time he sees it, since he's the guy who invented that enabling technology in the first place. All those HDTVs, digital movie projectors, and the digital displays used by so many schools and businesses? Hornbeck's research gave us that. And last week the American Institute of Physics rewarded him with its 2007 Prize for Industrial Applications of Physics, "for his invention and pioneering innovations in both the design and manufacturing of Digital Micromirror Devices (DMDs) integrated into metal-oxide semiconductor (MOS) technology." He can add that award to the Emmy he snagged in 1998 for the same technology, and his 33 (and counting!) US patents.

Just what are these miraculous mirrors? It just so happens I wrote a feature article back in June 1997 on the DMD technology. (You can read items from Physics News Update about DMDs here and here.) At heart, it is a complex, rectangular array of as many as 2 million microscopic mirrors nestled on an integrated circuit. Each mirror measures less than one-fifth the width of a human hair, if you need a comparison point to get a handle on the tiny scale we're talking about. The DMD acts like a light switch: each mirror is hinge-mounted so it can tilt on its, regardless of what the other mirrors are doing. This enables a digital image to be processed from a digital signal, because each mirror acts as a single pixel and can be switched on and off thousands of time per second, reflecting light onto a screen.

It all started back in 1997, when Hornbeck was working on building an analog light modulator for optical processing. He based the device -- which appeared four years later -- on a deformable mirror mounted on a metallic membrane. Then he got the idea for replacing that with an array of tilting mirrors connected by hinges, and the DMD concept was born. It was admittedly rudimentary, and too limited in how much light it produced to be immediately implemented into display applications, but Hornbeck and his TI colleagues did manage to develop a useful product: a ticket printer for commercial airlines. At the time, the airline industry was looking for a way to move past carbon-copy ticketing (older readers may remember those pre-e-ticket artifacts) with high-speed, high-resolution printing. The DMD proved ideal for that purpose.

The real breakthrough occurred in 1989, when DARPA awarded the company a $10 million grant to develop cutting-edge projection display systems. By then the DMD technology had sufficiently advanced optically that the notion was perfectly feasible. A year later, Hornbeck came up with the current design, and the first 640-by-480 pixel projection display using DMD appeared in 1992. Further improvements came fast and furious: the earliest devices had thousands of the tiny mirrors, but today's version boasts millions.

By 1997, when I wrote my article, TI was integrating the DMD technology with DLP, which proved to be the winning combination for the commercial marketplace. Thanks to the incorporation of DMD technology, the DLP chip is frequently described as "the world's most sophisticated light switch." Feed a digital or graphic signal to the chip, combine it with a light source and projection lens, and voila! All those tiny mirrors reflect a fully digital image onto your surface of choice (screens are nice).

Inside the DLP chip, the hinge-mounted mirrors tilt towards the light source for the "ON" position, and away from it to indicate the "OFF" position. "ON" corresponds to a light pixel on the screen, while "OFF" corresponds to a dark pixel. Various shades of gray (up to 1,024 -- I didn't know there were that many) can be achieved by switching on and off several thousand times per second. If a mirror is "ON" more than "OFF", it reflects a light gray pixel, and if it's "OFF" more than "ON", it reflects a dark gray pixel. The result is a high-resolution gray scale image.

But we don't live in a gray scale world, so the DLP system passes the white light generated by the lamp serving as an illumination source through a color wheel (or a prism) as it travels to the surface of the DLP chip, filtering the light into red, green and blue. The  "ON" and "OFF" positions for each micromirror are coordinated with those basic color building blocks, such that a mirror responsible for projecting purple (one purple pixel) will only reflect red and blue light to the projection surface. Our perception blends the rapidly alternating flashes of color and will "see" the intended color (purple) in the projected image. TVs, home theater systems and business projectors are 1-chip systems capable of producing at least 16.7 million different colors, while the more advanced 3-chip systems can produce a whopping 35 trillion colors. The mind boggles. Truly it does.

Is DLP perfect? Probably not -- nothing is. Its main competitors in the HDTV marketplace are LCDs and plasma flat panel displays, and each probably has its benefits and drawbacks. The closest competitor is Liquid Crystal on Silicon (LCoS), which uses a stationary mirror mounted onto a chip and relies on a liquid crystal matrix -- similar to those used in LCDs -- to control the reflected light. Thus far, DLP is holding its own quite well. More than 13 million DLP subsystems have been sold to date, with more than 50 manufacturers offering various models in late 2004. TI is reaping the economic benefits: DLP chips constitute a good 5% of the company's total sales.

Innovations are still being made, too. Early in September, TI showcased its high-definition 3D DLP technology at a major home theater and entertainment industry expo (CEDIA), which gives 3D stereoscopic capability to existing HDTVs for a truly immersive viewing experience. Now you can truly feel like you're in the midst of the action if you're watching a spectacular chase scene or action sequence -- and it's designed for easy adaption of existing 3D computer games, which should give all hardcore gamers a warm, happy feeling. This latest innovation builds upon DLP Cinema, launched a few years ago and now in use on more than 4500 movie screens globally. This was a boon to films like Meet the Robinsons, Harry Potter and the Order of the Phoenix, and Beowulf, all of which were shot in 3D. Industry buzz has it that Hollywood intends to expand the number of 3D theatrical releases in the future.

And to think, it all started with one small deformable mirror and the fertile imagination of a gifted , creative physicist. The next time you're at a cocktail party and someone wonders aloud how all this high-falutin' digital TV and 3D cinematic technology is possible, you can bask in the warm glow of superior knowledge, lean over, and whisper the industry's secret: they do it with mirrors. Be sure to mention Hornbeck -- a.k.a. The Founding Father -- by name.

e is for energy

We have not been slacking off on blogging, truly we haven't -- we've just been doing it over at the official blog for the 2007 Industrial Physics Forum all week long. I missed writing an official post for Monday's big "blog for the environment" movement, but as it turns out, I've been learning and blogging all week long about global warming/climate change, the global energy crisis, and the latest advances in alternative energy sources and mitigation strategies. I should get bonus credit! It's been intense: 2-1/2 days of non-stop sessions with blogging in between. We're feeling a bit frazzled and exhausted after three 16-hour days. Also a bit depressed, since that whole global energy crisis? It's big-time serious. And we're running out of time. Fast.

Anyway, to give you an idea of what we've been up to, here's the titles and first paragraphs of the seven IPF posts so far (there'll be one or two more on Friday.) Click on the link to read the entire post.

Think Big, Go Small.
The semiconductor industry has been dominated by "Moore's Law" for decades. Every time it seems we're about to reach the threshold beyond which chip size and density can't possibly go any further, some new breakthrough prolongs the lifetime of the silicon chip just a little bit longer. Too bad we're not making comparable strides in the energy sector, because without sufficient energy, how will those sturdy little silicon chips be able to run? Kicking off the 2007 Industrial Physics Forum with an overview of the energy landscape, MIT's Mildred Dresselhaus recommended that we "Think big and go small," and called for "a Moore's Law" for energy efficiency. "A few percent in improvement means nothing" in the grand scheme of things," she insisted: "We need an order of magnitude improvement." [Read more!]

Drive Me Crazy.
I confess: I own a Prius. It's not that I think my little hybrid car will single-handedly save the planet, because despite the improvements in fuel efficiency, I'm still burning fossil fuels and putting more carbon into the atmosphere. But it's a start, because hybrids are an economic bridge to the electric cars of the future, according to Michael Tamor, an executive technical leader at Ford Research who spoke this afternoon on the re-electrification of the automobile. "A consumer product will always succeed or fail based on customer value," said Tamor. Indeed, the commercial success of the Prius -- and of the emerging fleet of other hybrid vehicles, from Ford and other automakers -- is due in large part to the fact that people believe they are reaping enough benefits (environmentally and in fuel efficiency) to justify the higher price tag. [Read more!]

Waste Not, Want Not.
"What am I, chopped liver?" That's what the entire field of thermoelectrics (at least as it relates to waste heat recovery) wants to know. In a field of showy alternative energy candidates like biofuels, solar cells, fuel cells, and powerful wind turbines, the challenge of eking out bits of excess energy that would otherwise be wasted as heat to make incremental improvements in energy efficiency seems a bit, well, proletarian. One could almost envision the poor, lonely drudges doomed to try and recover snippets of wasted heat energy for all eternity in Dante's Ninth Circle of Hell, while Lucifer looks on and snickers. In short, it's a thankless task. Small wonder Lon Bell (BSST LLC and NREL) jokingly calls his work in this area "the chopped liver of new technologies." [Read more!]

LED-ing the Way.
One of the standout attractions at Chicago's Millennium Park is the Crown Fountain. On either side of a reflecting pool are two 50-foot glass block towers. Underneath those glass bricks are LED video screens that, when illuminated, showcase videos of the faces of nearly 1000 Chicago residents, in random rotation, all smiling out at the world while a stream of water cascades over their visages. ... The most central technology that makes the Crown Fountain possible is the light-emitting diode (LED). During this morning's session on energy efficiency, Shuji Nakamura of the University of California, Santa Barbara, outlined the current status of LED-based solid state lighting, and some of the existing and emerging applications for these ingenious little devices. [Read more!]

UPDATE: Stefan at Backreaction has an excellent post up about Nakamura's recent pioneering work on blue LEDs. Jen-Luc sez check it out!

The POSEIDON Adventure.
Casting about for some small thing you can do to be environmentally responsible? You can always disconnect your doorbell. So says David de Jager, an energy and environmental consultant with E-Concern in The Netherlands. He opened his Tuesday morning presentation by pointing out that an electrical doorbell is pretty much hooked up all the time and therefore draws about 5 watts continuously year-round -- more if it's lit up, and when someone presses it. This works out to something like .01% efficiency, according to de Jager. In fact, the power required to connect all the doorbells in Europe is equivalent to the power output of two coal-fired power plants, all for a convenience we barely use. Quoth de Jager: "This is idiotic." Especially for those of us who don't receive many visitors. [Read more!]

Carbon, Carbon, Everywhere.
There's been a great deal of uproar this past week over the controversial awarding of the 2007 Nobel Peace Prize jointly to the UN's Intergovernmental Panel on Climate Change (IPCC) and former vice president Al Gore for their work on raising awareness of climate change and global warming. For all the inevitable politicizing of the issue, what the Nobel Prize Committee's decision truly augurs is the recognition by the international community that global warming is real, and we're quickly running out of time to reverse the potentially catastrophic trends. Honestly? It's probably already too late for merely implementing mitigation strategies, according to Rosina Bierbaum of the University of Michigan. [Read more!]

"Busy Old Fool, Unruly Sun..."
Based on the above opening lines from one of his most famous sonnets, the 17th century metaphysical poet John Donne wasn't a fan of Le Soleil. Maybe he just wasn't a morning person, but I suspect the scientists who've been working on photovoltaics for decades, struggling to raise conversion efficiency rates a few points at a time in hopes of some day, in the distant future, making it a commercially viable energy source, might share Donne's frustration. After all, the sun has, to date, proven to be fairly intractable when it comes to harnessing its rays to power our energy-hogging homes. [Read more!]

UPDATE: One more post, not energy-related, from the Frontiers in Physics session:

Measure for Measure
Harvard's Gerald Gabrielse -- who kicked off this year's "Frontiers in Physics" session, which traditionally closes the IPF -- has earned his fair share of professional kudos from the physics community for his groundbreaking research at CERN in Switzerland, coming up with nifty new ways of trapping single particles to study them up close and personal. For instance, back in 2002, his team made science news headlines when they published two papers in Physical Review Letters providing the first glimpses inside an antihydrogen atom. More recently, he's used similar methods to make the most precise measurements to date of the electron's "magnetic moment" -- a finding that AIP's Physics News Update dubbed its scientific breakthrough of the year in 2006. [Read more!]

Whew! I'm getting exhausted all over again reading over that. We'll be back to regular posting at Cocktail Party Physics on Monday, and in the meantime -- the links above should give you plenty to read, and fret over. Me, I'm off to unplug my doorbell and turn off all the lights...

into the void

Nature might abhor a vacuum, but Seattle is embracing the void -- at least for the coming week, when the Emerald City hosts the 2007 annual meeting of the American Vacuum Society. I'm in town to cover one small aspect of the conference, the Industrial Physics Forum (IPF), organized this year around the theme of meeting future energy needs, with sessions on hydrogen and fuel cell automobiles, solid state lighting, photovoltaics, biomass, wind and geothermal energy sources, and an entire session on nuclear power (both conventional and the fusion-based ITER facility now under construction). Things will be a bit quiet at the Cocktail Party this week, since I'll be blogging the IPF sessions, along with some representatives from the Society of Physics Students. It's a continuation of last year's blogging experiment, except I've learned not to promise live blogging, after the dismal wireless access I encountered at the 2006 IPF conference. Feel free to pop on over and check out what's going on over the next few days.

I'm hoping the IPF doesn't keep me so busy that I miss out on the special exhibit on vacuum history -- and this being a physics blog, you know I don't mean Hoovers. (It's a common mistake: the AVS has fielded so many calls from people looking for repair information on their vacuum cleaners that one year, they made up buttons and stickers featuring a vacuum cleaner in the middle of a red circle with a line through it, a la Ghostbusters.) Because I love physics history, and vacuum technology has some pretty fascinating tales buried amongst all the usual tedium. Vacuum technology in general has become so commonplace in science, it kinda gets taken for granted. But it's a crucial enabling component to so much of modern-day science and technology, from incandescent light bulbs, vacuum tubes, and industrial manufacturing to double-paned windows, thermos bottles, vacuum packing, even giant particle accelerators like Fermilab's Tevatron, or the Large Hadron Collider.

The standard definition of a vacuum, per Wikipedia, is "a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than standard atmospheric pressure." Right away, you should see a problem with that: we now know that space can't be perfectly empty, thanks to the presence of virtual particles popping in and out of existence in the quantum vacuum on time scales so short as to be undetectable by our cutting-edge scientific instruments. But that's a "perfect" vacuum. We can certainly achieve partial vacuums, and have done so for millennia. It's hard work, though, and the lowest pressures we can currently achieve in a laboratory are about 10<-13> Torr.

The first recorded experiments on the existence of vacuum were apparently conducted by an Arab philosopher named Al-Farabi in the 9th century AD, using handheld plungers in water. That's when he realized that the volume of air would expand to fill any available space. Later scientists figured out how to create better and better artificial vacuums, thanks to the principle he delineated. Here's the basic idea: By expanding the volume of a given container, pressure is reduced and a partial vacuum is created. It's temporary and is soon filled by air pushing inside by atmospheric pressure, but if the container is repeatedly sealed, the air pumped out, expanded again, and closed off, it's possible to create a sealed vacuum chamber. Today there is a staggering diversity of approaches to vacuum pumping. It's a very lucrative industry, one of the largest market sectors of scientific instrumentation today.

Vacuum is measured in units of pressure. Technically, the standard unit of pressure is the Pascal, but scientists can't possibly let things be so simple, so they came up with a new unit for vacuum pressure, the Torr, named after 17th century Italian physicist Evangelista Torricelli, best known for inventing the barometer. (He also has an asteroid named after him.) As with many useful inventions, he wasn't actually trying to invent a barometer. He was trying to solve an intriguing conundrum, namely, how to raise water levels in a suction pump to more than 32 feet in height -- the limit pumpmakers had been able to reach using simple suction pumping. It seemed that perhaps Nature truly did abhor a vacuum, but Galileo Galilei cheekily suggested that perhaps the abhorrence only extended to 32 feet. He knew a little something about the weight of air versus other substances, and thought it might be possible to overcome the obstacle using something heavier than water.

Inspired by Galileo's insight, in 1643, Torricelli hit on the notion of using mercury, which is much heavier than water (14 times heavier, in fact), in a simple experiment: he filled a three-foot-long tube with mercury and sealed it on one end, then set it vertically into a basin of mercury with the open end submerged -- being careful, obviously, not to introduce any air bubbles into the tube. The column of mercury fell about 28 inches, leaving an empty space above its level, creating an early version of a sustained manmade vacuum! Torricelli further realized that (a) the mercury would rise to the same level regardless of how tilted the tube became because the pressure of the mercury would balance the weight of the air, and (2) the height of the column of mercury rose and fell according to changing atmospheric pressure. Voila! The first barometer.

In 1650, a German scientist named Otto von Guericke built a contraption known as the Magdeburg hemispheres -- the world's first artificial vacuum. He took two large copper hemispheres with rims that fit tightly together, sealed the rims with grease, and pumped out all the air. To do so, he had to invent a vacuum pump; his version used a piston and cylinder with flap valves, powered by people turning a crank arm that was connected to the pump. Anyway, once all the air was removed from within the hemispheres, they were still held together by the air pressure of the surrounding atmosphere because the artificial vacuum inside provided no opposing pressure to balance things out. It was a pretty powerful hold, too. Four years later, von Guericke harnessed a team of eight horses to one hemisphere of the big coppery globe, and another eight horses to the other hemisphere, and then set the horses to pulling the two hemispheres apart by moving in opposite directions -- to no avail.

News of the experiment quickly spread throughout Europe, eventually reaching the ears of Robert Boyle, founder of modern chemistry, in England. Few scientists were able to replicate von Guericke's feat because it was an expensive apparatus. (Their collective minds would boggle at the price tag for modern experiment contraptions like the LHC, LIGO and ITER.) But Boyle had the 17th century equivalent of a trust fund, being the son of the Earl of Cork, so he cheerfully set about building his own "pneumatic engine," cost be damned. To do so, he enlisted the aid of Robert Hooke of Micrographia fame, then Boyle's humble assistant. Hooke had a gift for instrumentation, which is a good thing, because Boyle's design was a clunky, difficult to operate device, and sometimes Hooke was the only one who could get the thing to work properly.

In addition to public demonstrations, Boyle conducted many different experiments to determine the properties of air, specifically how "rarefied air" affected things like combustion, magnetism, sound, barometers, and various substances. He carefully detailed his observations for posterity in a very thick book ponderously titled, New Experiments Physico-Mehcanicall, Touching the Spring of the Air, and its Effects (Made, for the Most Part, in a New Pneumatical Engine). Boyle clearly lacked the gift of catchy titles. Jen-Luc Piquant would have called it something more dramatic, like Asphyxiated! Staring Into the Void of the New Pneumatical Engine. Two of Boyle's experiments involved living creatures: one tested whether insects could fly under reduced air pressure, while another dramatically showed how crucial air can be to the survival of various creatures. Boyle used birds, mice, eels, snails and such in these experiments, placing them in the vessel of the pump and studying how they reacted as the air was slowly removed. The most famous passage described a lark's response:

"... the bird for awhile appear'd lively enough; but upon a greater Exsuction of the Air, she began manifestly to droop and appear sick, and very soon after was taken with as violent and irregular Convulsions, as are wont to be observ'd in Poultry, when their heads are wrung off: For the Bird threw her self over and over two or three times, and dyed with her Breast upward, her Head downwards, and her Neck awry."

One might be forgiven for concluding that Boyle had to be one cold bastard to stand there and watch the poor innocent lark slowly suffocate to death in the name of science. Certainly audiences found the sight extremely upsetting, so much so that by the 18th century, live animals had been replaced in most such public demonstrations by a "lungs-glass" with a small air-filled bladder inside that simulated the effects of the vacuum on living creatures. Boyle's controversial approach to experimentation was immortalized in 1768, however, by the painter Joseph Wright of Derby. His canvas, An Experiment on a Bird in the Air Pump, depicts a scientist recreating Boyle's experiment with a white cockatoo, as his children and a couple of fellow scientists look on.

Vacuums serve as asphyxiants. That's what Boyle et al. learned from their experiments, and its natural to wonder what effect the vacuum would have on human beings. Well, now we know. Humans will lose consciousness after 10 seconds or so, and die within minutes, although contrary to popular depictions in movies, the body does not explode. True, the bodily fluids, like blood, could theoretically start to boil (ebullism), but this is, apparently, unlikely, at least in outer space. And vapor pressure causes substantial bloat, but the tissues are elastic and usually expand in response, preventing gross-out "ruptures." 

Unless the victim holds his breath during decompression: that would be a big mistake, since this could rupture the lungs, causing death. Or the eardrums could rupture. Or the stress will make you asphyxiate. All in all, it's best not to hold your breath. Thanks to Boyle and subsequent animal experiments (not to mention gruesome Nazi experiments in 1942 involving tortured concentration camp prisoners in Dachau), we also know that living things can recover from short exposures to the vacuum (fewer than 90 seconds); no one has yet succeeded in resuscitating victims of longer full-body exposure. According to this Website, one of NASA's test subjects was accidentally exposed to a near vacuum because of a leaky space suit back in 1965. He was conscious for 14 seconds, and was successfully revived when the vacuum chamber was repressurized, but distinctly recalled feeling the water on his tongue beginning to boil.

I'm not personally keen on staring into the vacuum void myself anytime soon, but I do think it's nice to occasionally give the technology a little bit of recognition. Without vacuum technology, our science experiments wouldn't work, there would be no thin film deposition (and no nanoscale materials), plus our lighting would be hopelessly inefficient, and we wouldn't have thermos bottles to keep our coffee hot, and our iced tea cold. The vacuum: way cooler than a Hoover and even more useful.

magnetic moments

Last Christmas I bought my youngest niece, Cami, her very own iPod Nano, much to the relief of her older siblings, who were tired of Cami constantly "borrowing" theirs. Her reaction was priceless: she gasped, she squealed, tears came to her eyes, she hugged the little device to her chest with eyes cast heavenward in gratitude. (I predict a stellar career as an actress when she grows up.) She's not even 10 yet, so to her, it's just a wondrously magical device in a pretty color that holds her favorite tunes. She has no idea how it actually works, or that the iPod just won the 2007 Nobel Prize in Physics.

Okay, the iPod, per se, didn't win the Nobel Prize, just the fundamental physics research on which it is based. I just threw that comment in there to make the chronic curmudgeons grit their teeth at the media's insistence on trumpeting about the iPod instead of talking about the actual science being honored this week by the Nobel selection committee. But we here at Cocktail Party Physics join the rest of the physics blogosphere in congratulating Albert Fert (Universite Paris-Sud, Orsay, Franch) and Peter Gruenberg (Julich Research Center, Germany) on being awarded this year's Nobel Physics Prize for their  independent discovery of giant magnetoresistance (GMR), which has given us not just the iPod, but also high-density hard drives in general, high-density magnetic random access memory (MRAM) and a budding new field called spintronics. Anyone dying to get the fundamental physics scoop can check out this nifty background site (courtesy of IBM), or, for the truly technical minded, read the original papers on GMR as published in Physical Review Letters and Physical Review B.

Of course, if you really want to be all fundamental about it, this year's Nobel Prize in Physics has roots stretching all the way back to 900 BC, when a Greek shepherd named Magnes supposedly walked across a field of black stones, which pulled the iron nails out his sandals. He dubbed the region Magnesia. That's the legend, anyway, and who are we to argue about it? Certainly strange magnetic effects were known to the natural philosophers of antiquity, and by 1269 AD, some French dude named Petrus Peregrinus had figured out that so-called lode-stones -- basically naturally occurring spherical magnets of iron-rich ore -- could be used to make rudimentary compasses, although people didn't fully understand how or why they worked until 1600, when William Gilbert, court physicist to Queen Elizabeth I, discovered that the Earth itself is a giant magnet.

There were more mysteries of magnetism yet to come. In 1820, a humble physics professor at Copenhagen University named Hans Christian Oersted discovered that electricity and magnetism weren't two separate things, but were closely related -- more like flip sides of the same coin. He discovered this quite by accident while playing around in the lab with heated wires and compasses, among other scientific paraphernalia. He was merely trying to demonstrate the basics of magnetism and how electrical current can heat a wire, using a simple compass needle mounted on a wooden stand as a makeshift magnet. He noticed that every time the electric current switched on, the compass needle would jump in response. No doubt he thought to himself, "huh... that's funny!" -- which invariably heralds most major scientific breakthroughs. He found he could repeat the same effect, over and over again, in his lab, with more sophisticated apparatus. And the study of electromagnetism was born, bringing breakthrough after breakthrough as the giants of physics history (Faraday, Maxwell, Hertz, et al.) set themselves to the task of delving deeper into this phenomenon.

I won't even attempt to summarize the vast number of pioneering breakthroughs and revolutionary research that took place in the aftermath of Oersted's discovery -- although it is worth mentioning that back in 1857, famed British physicist Lord Kelvin demonstrated that electric resistance of materials such as iron could be influenced by a magnetic field (the basis for modern induction coils, the significance of which will become clear below). Let's just fast forward a couple of centuries to the 1980s, when two teams of researchers in France and Germany, led by Fert and Gruenberg, respectively, were building alternating ultra-thin layers of magnetic and non-magnetic atoms at the nanoscale. At those tiny scales quantum effects begin to hold sway, so fundamental properties of materials are altered.

For instance, an electron's spin becomes a much more important factor. "Spin" is a misleading term, in that in the minds of a layperson such as myself, it tends to conjure up an image of a spinning top. An electron spin is something quite different, and under the right circumstances, infinitely more powerful. To quote an article published last January by Lawrence Berkeley Laboratory:

"Spin is a quantum mechanical property that arises when the rotational momentum of a particle, in this case an electron, creates a tiny magnetic field. For the sake of simplicity, spin is given a direction either 'up' or 'down.' Just as the positive or negative values of an electrical charge can be used to encode data as the 0s and 1s of the binary system, so too can the up and down values of spin. Unlike charge-based data storage, however, spin-based storage does not disappear when the electrical current stops."

The shorthand version: Electron spins generate a magnetic field, and can be aligned either "up" or "down." The big breakthrough occurred when the French and German teams realized they could use spin orientation at the nanoscale to effect very large changes in the electrical resistance of layered materials, even if the changes in magnetic fields were very weak. That hunch proved correct. Fert and Gruenberg found that when all their nanoscale layers were aligned in the same direction, electrons with the same alignment would pass right through the material, but the electrons would be blocked if they had the opposite alignment. Independently of each other, they wondered what would happen if the layers were organized in an alternating up-down alignment. They found that in such instances, all electrons encountered some resistance, giving rise to a much higher level of resistance than had previously been observed.

How much higher? According to the Nobel background materials, Fert's group observed "a magnetization-dependent change of resistance of up to 50%," while the German group, led by Gruenberg, saw a 10% difference. Fert used many more layers, giving rise to a stronger GMR effect, but even Gruenberg's 10% difference was a vast improvement: with traditional magnetoresistance, barely a single percent of change in resistance had ever been observed. You didn't need to be a rocket scientist to know this was a major breakthrough; Gruenberg had the foresight to file a patent as he was writing up the results for publication, realizing (as did Fert) that such an effect would have an enormous impact on technology.

On a practical level, this was very good news for magnetic hard drive technology. Hard drives store data in patterns of magnetic fields, and metal induction coils (thank you, Lord Kelvin!) are then used to read out the data. The problem was that there were some fundamental physical constraints that limited how small those induction coils  (and data bits) could get; the magnetic signals quickly became too faint to be accurately detected at those smaller scales. The GMR effect meant that even a tiny magnetic field -- like the one on the surface of a computer hard drive -- can trigger a very large change in electrical resistance, and this effect can be exploited to "read" any data encoded in that surface's magnetic orientation. So much more information can be packed into a very small space, and still be "read."

Even better, later research found that one didn't need to create the ultra-thin layers using the labor-intensive and costly process of epitaxy; a sputtering process worked just fine, and could be easily scaled up to commercial volumes, because the GMR effect wasn't dependent on creating highly precise (at the atomic level) layers. The first devices based on GMR appeared in 1997, and the rest is history. MP3 players have been shrinking ever since: I have a full-sized iPod with a whopping 60 GB storage capacity, and a teensy iPod Shuffle for gym workouts that is about the size of a postage stamp, yet can still hold a good 250 songs.

GMR has also given rise to a magnetic alternative to dynamic random access memory (DRAM) called, appropriately, Magnetic Random Access Memory (MRAM). Everyone's familiar in theory with RAM: it's the temporary storage of data on your computer before you hit "save" and your hard work gets copied over to the hard drive for more permanent storage. At least, that's what happens if all goes well and there isn't a power outage, or a faulty sector on the hard drive, or, or, or...  My senior year of college, I was feverishly writing the final draft of my senior thesis, and got so involved in the actual writing that I failed to keep saving the file every half hour or so. And wouldn't you know it, I got the Blue Screen of Death and lost much of the last third of my revised paper. Foul language filled the computer lab for a good 10 minutes before I resigned myself to my fate and stayed up all night to rewrite what I'd lost.

That sort of thing is still happening occasionally to computer users everywhere, even all these years later. GMR could put an end to such tragedies. Thanks to GMR (and its offspring, Tunneling Magnetoresistance), it is possible, in principle, to use these effects for both reading and writing information, so MRAM could be used as a permanent working memory without a hard drive's dependence on electric power.  Computers using MRAM memory chips don't need to be booted up to move hard-drive data into memory, and the chips can store more data in a much smaller space, and access it much more quickly, than with conventional DRAM. Ultimately this means even more miniaturization, something that any product using embedded computers would welcome (cars, for instance). And that's not even counting the budding field of spintronics.

So, sure, GMR is fundamental physics, but a big part of its importance stems from its usefulness for a broad range of applications -- some of them potentially revolutionary. I understand why some physicists are a bit miffed at all the play the iPod has been getting in the press as a result of this, but honestly, the Nobel website itself specifically plays up that aspect, and made the selection in part because it's such a terrific example of how fundamental research can lead to cutting-edge technology, which in turn feeds back into fundamental research -- in this case, possibly enabling future breakthroughs in nanotechnology and quantum computing.

Personally, I'd find it gratifying  if I were a physicist and my basic research revolutionized the music industry the way the iPod has done. Fert, for one, doesn't seem to be too upset about all the attention being paid to the iPod and all the other spinoff technologies made possible by GMR. "These days, when I go to my grocer and see him type on a computer, I say, 'Wow, he's using something I put together in my mind.' It's wonderful," he told the Associated Press.

Nor is he kicking himself over not filing a patent claim, like Gruenberg did when the effect was first discovered. He's got half of a $1.5 million Nobel Prize to play with, after all, and told France's Inter Radio about his plans to share some of that with the colleagues who aided his ground-breaking research. Oh, and he also plans to buy some new sails for his windsurfers. Fert is Jen-Luc Piquant's new personal hero, and I can understand why. When I get to be 69, I hope I'm as relaxed, confident and personally fulfilled, and still physically capable of controlling a windsurfing contraption -- perhaps listening to my implanted (and waterproof!) MP3 player, made even tinier thanks to advances like GMR.

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 elast