Cocktail Party Physics

they'll have the escargot

For years, my friend Peri and her erstwhile husband had their very own imaginary friend. Known simply as "Snail," he was rarely seen, but often heard from, in the form of cryptic notes, emails, and the occasional postcard sent from France (or London, or Italy, or wherever her itinerant artist spouse was traveling at the moment). Snail went on to found his own imaginary artzine, Gastropod Cineaste (with a heavy emphasis on French New Wave films). Yes, Snail had a touch of intellectual snobbery; Jen-Luc Piquant simply adored him, dubbing him "mon petit escargot," despite the whole mucus thing.

Mucus, you say? Mais oui! That's how a snail gets around, after all, even those that dwell in the realm of imagination. Snails store a crystalline form of their mucus and then mix it with liquid to produce the long sticky trails of slime they leave in their wake. It's all about equal and opposite reaction: the snails push backward to create a pressure gradient that propels them forward. Mucus might be a bit gross to homo sapiens, but for snails, it's a miracle substance, enabling the creatures to crawl over all kinds of uneven terrain: sand, mud, ground scattered with leaves or twigs. And if they encounter a wall or ceiling, no problem! Thanks to the sticky stuff, they can maneuver those non-horizontal surfaces just fine.

Smart scientists know we can learn a lot from Mother Nature, and a bunch of folks at MIT are looking to how snails do the locomotion for insight into building robotic snails. Anette "Peko" Hosoi and a few of her students introduced Robosnail Version 1.0 back in 2003: a six-inch long machine, just one inch wide, that could "glide" over a thin film of silicon oil -- their version of mucus, called Carbopol, which is simply a gel-like, water-based polymer solution. There's lots of fascinating information -- like the fact that snails have three different modes of locomotion, including a bizarre kind of "gallop" --contained in MIT's 2003 press release on the subject.

If Robosnail dates back to 2003, why am I even bringing it up? Well, the latest iteration was just described in talks by Hosoi and her collaborators at the recent (November 19-21) meeting of the APS Division of Fluid Dynamics in Tampa Bay, Florida. It's a fluids-related project because it could provide insights into how blood flows through a vein. Like blood flow, snail movement is essentially a fluid flow contained by a flexible boundary. Anyway, Robosnail Version 2.0 is even more impressive than its predecessor: it can climb walls and move upside, thanks in large part to its light weight (less than 31 grams) and a slick layer of another mucus-like substance called Laponite. One promising application is the use of Robosnails to aid in oil exploration by maneuvering through harsh, hard-to-reach environments. Surgeons might also find them useful to  crawl to hard-to-reach areas of the body. These are pretty far afield in terms of development but Robosnails 1 and 2 are the first exploratory tools to that end.

There are some drawbacks to the snail's otherwise ingenious approach to locomotion, namely, it's not exactly energy-efficient (or fast). Slugs, for example, also move along trails of excreted slime. Marine scientist Mark Denny of Stanford University, who studies slugs, says they expend 70% of their energy making those mucus trails. That's about 10 times more the energy expenditure of animals that move by running, swimming, or flying. Mile for mile, it might not be the best choice for locomotion, unless there's no better alternative means of movement.

Speaking of the lowly slug, there's also a swarm of slugbots in the works. I kid you not. Ian Kelly of the University of the West of England, has been working on this project since, oh, about 2000. His little battery-powered robot is designed to patrol fields looking for slugs and scooping them up, using their decaying bodies to recharge its batteries -- a concept that seems like he ripped it straight out of The Matrix. British farmers purportedly spend some 20 million pounds a year trying to prevent invading armies of slugs from devouring their tender crops. (I grew up in the Pacific Northwest, and a sprinkling of salt does the trick. But slugbots are just so much cooler!) Kelly estimates that as many as 200 slugs could be found for every square meter of a wheat field, providing a bounteous source of energy for his slugbot.

These are the kinds of fascinating scientific tidbits you can pick up by hanging around fluid dynamics meetings, or least browsing their online abstracts and epitomes. I'm sad to have missed the DFD meeting, which also featured the following nifty papers:

* Scientists at Tokyo University (Seiji Ichikawa and Osamu Mochizuki) are trying to mimic the swimming motion of a jellyfish by building a micro-robot out of an unspecified "soft material." My knowledge of the locomotion of jellyfish is a bit imprecise -- mostly they seem to just float about, waiting for the perfect opportunity to sting someone -- but they can produce thrust, and thereby some momentum, by creating a "vortex ring." Basically, they can expand and contract their mushy little bodies and expel air into the water behind them, creating a little whirlpool that gives them a shot of propulsive power. Jellybots -- can't wait to see the prototypes! 

* A collaboration among scientists at Philips Research and Eindhoven University of Technology are also drawing on biological phenomena, this time to aid in in the design of better micro-actuators. Many micro-organisms, like paramecium, have small hairs or flexible rods (called cilia) attached to the surface, a natural covering that can beat, like tiny wings, to induce fluid flow. (Fluids, for the non-scientifically inclined, technically include air and those nasty gels currently being targeted by the TSA, not just liquids.) The Philips/Eindhoven team have built "artificial cilia": very tiny actuators made out of polymers that qualify as "smart materials" -- that is, they change shape or size in response to an applied electrical or magnetic field. The expansion/contraction of the artificial cilia mimics those found in nature, and can induce some fairly significant velocities of fluid flow. The hope is that this will be a new means of micro-fluidic actuation to control flow in tiny biosensors.

* MIT is just a hothouse of innovation, isn't it? Also on hand at the DFD meeting were Manu Prakash and Neil Gershenfeld. Gershenfeld runs MIT's Center for Bits and Atoms, and is perhaps best known for his fervent espousal of the coming revolution in personal "fab labs." He and Prakash, however, are working on an entirely different project involving bubbles. Bubbles can be problematic for fluid dynamicists because they're so difficult to control, and can seriously affect the smooth flow of a fluid. For P&G, the formation of bubbles offers a unique opportunity for microfluidic "bubble logic". Presence or absence of a bubble would represent a "bit," so bubbles could carry both information and some sort of material "payload" at the same time. The men have experimented already with creating microfluidic bubble logic gates and memory, with an eye towards applying this approach to large-scale integrated biochemical processors.

* Einstein apparently once observed the motion of tea leaves, noting that they tend to centrally accumulate at the base of a stirred teacup. Monash University researchers led by James Friend find this to be a useful analogy for their new method for microfluidic blood plasma separation in miniaturized blood diagnostic kits. Their technique also uses an electric shock of sorts to generate a form of thrust inside a microfludic chamber. They noted that the colloidal particles they deliberately suspended in the liquid swirl about and deposit at a "stagnation point" at the center of the chamber's bottom, just like Einstein's tea leaves. Can microfluidic-colloidal-particle fortune tellers be far behind?

Each one of these could probably be a blog post in and of itself, but there's just no time to do the topics justice. Because this coming week, it's all about sound. We're in Hawaii now, for the fall meeting of the Acoustical Society of America. I have a fantastic ocean view from my hotel room balcony, which conveniently looks out onto Waikiki Beach. (I slept with the sliding glass doors open to let in the sound of waves breaking on the beach, which explains my Fourier-transform-enhanced dreams.) I'll be posting occasionally about any acoustics talks of particular interest (or befuddlement, on the off chance my readers can be of assistance). And maybe there'll be time to tour a volcano, take a few hula lessons, or take in some quality rays before I return to the chilly Northeast.

feast or famine

The last month has been pretty brutal for me in terms of travel: it seems like every few days I'm hopping on an airplane and crossing time zones (for both personal and professional reasons). I don't have it nearly as bad as certain physicists, but my schedule is only going to get worse come January, when I start hawking my forthcoming book in earnest. Getting around is so much easier for Jen-Luc Piquant, who can zip around the world in Cyberspace via that cunning series of tubes that is the Internet. I've long envied her ease of transport. So I was pleased to learn that Boeing is creating a plane called the 787 Dreamliner specifically designed to help combat the causes of jet lag, based on a battery of experiments on several hundred people.

Just what are those causes? According to the folks at Boeing, the list includes lighting, pressure, humidity, and air quality. At least, those are the factors they can address with their innovative new design, which incorporates wider seats and aisles, a wider cabin, larger lavatories (a boon to those who aspire to join the Mile-High Club, or less ambitious folks, like me, who would just like to be able to maneuver a little better in a cramped and tiny space) and windows that are 65% larger than those in conventional airplanes. Those windows are also outfitted with electro-chromic window shades to passengers can dim them while still being able to see outside. Light-emitting diodes simulate both the brightness and color of the aircraft's ceiling to give a sense of daylight when needed, or simulate a lovely nighttime sky. Oh, and they're incorporating an innovative new air purification method called gaseous filtration to reduce airborne contaminants that Boeing's studies have found cause many of the symptoms associated with low humidity.

It's nice to see an airplane manufacturer that actually cares about passenger comfort and well-being, since the airlines themselves seem to be hell-bent on making flying the not-so-friendly skies as unpleasant as possible these days. But we're skeptical about how much the new design can actually combat jet lag. At best, it might alleviate the symptoms. Because, let's face it, the real cause of jet lag is flying across all those different time zones and having to readjust one's internal clock/circadian rhythms to be in sync with one's new location. Even Boeing spokesman Mike Sinnett admits "We can't guarantee people won't have any jet lag, but it should be a much better experience." 

It's too early for the new design to benefit everyone who flew to a different time zone for the Thanksgiving holidays this year, but I was pleased to stumble upon the Anti-Jet Lag Diet, apparently practiced by athletes, among others, to reduce the effects of crossing time zones over and over and over again. The most notable strategy is alternating days of feast and famine from a few days before, to a few days after, your planned trip across time zones.

On feast days, you're supposed to eat three full meals, with breakfast and lunch being particularly high in protein, since it supposedly helps the body produce the chemicals it would normally produce when it's time to wake up. ("Take second helpings!" the site suggests, although Jen-Luc points out that this is hardly good advice for a nation already beset by an "obesity epidemic.") Feast-day dinners, in contrast, should be rich in carbohydrates to help the body produce those chemicals it would normally produce around bedtime. Fast days consist of three small meals low in both carbs and calories: salads, soups, half-slices of bread... or you can just make do with crappy airline food in minuscule portions (no longer complimentary on most domestic flights).

I don't know if the Anti-Jet Lag Diet works or not, but I inadvertently followed it for my Thanksgiving holiday. How handy is it that the day before is a fast day, and you have the perfect excuse to pig out on the holiday itself? ("I need a third helping -- it's a feast day! My internal clock demands it!") Speaking of Thanksgiving and turkey, everyone seems to be bringing up the whole turkey-and-tryptophan issue in honor of the holiday, but I wrote a short article on the subject last year -- about growing scientific evidence that the amino acid might play a vital role in sleep and mood control, even if it's not to blame for that sleepy feeling after a big Thanksgiving feast -- and don't really feel inclined to rehash everything here, especially since Coturnix has posted such a good recap over at A Blog Around the Clock. Instead, I'll just point you to this interesting piece in Wired last year about the next generation of cooking tools for science-minded cooks.

The article opens with an anecdote about Michael Chu, founder of the Cooking for Engineers Website, who came up with an ingenious method for cooking the family's Thanksgiving turkey. He stuffed an open 24-ounce can of beer into the stomach cavity (where the stuffing usually goes) and smoked the turkey while steaming it from the inside with the evaporating beer. Now, I know from watching Emeril on the Food Network that beer-brine chicken and similar dishes purportedly are tastier and more moist than similar meats prepared in more traditional fashion, but it would never have occurred to me to just stick an open can of beer into a turkey to test tat theory. I guess that takes an engineer. Chu himself admits that he's not sure the beer adds much flavor to the chicken, but the finished product was apparently tasty, nonetheless.

Let's chat for a moment about what happens when you drop that piece of succulent breast or thigh meat onto the shag carpet that adorns the dining room. Assuming the family dog doesn't beat you to it, do you pick it up and pop it in your mouth, or reluctantly toss it for fear of contamination? I've always been a fan of the "five-second rule" myself, but I'm starting to have second thoughts about the wisdom of that after reading about a series of experiments performed by Paul Dawson, a food scientist at Clemson University. Dawson and his colleagues wanted to know how much time it would take salmonella to stick to bologna and bread, respectively, after the food items were exposed to contaminated wood, tile and carpet surfaces.

They found that salmonella can survive for up to four weeks on dry surfaces, in sufficiently high concentration to be transferred to foods. (Yikes!) Not only that, but the salmonella can be transferred to the foods almost instantly, five-second rule be damned. Tile is the worst such surface in terms of rapid transfer rate: 99% of bacteria cells were transferred from the contaminated tile to the bologna after five seconds of exposing the poor unsuspecting luncheon meat to the tile. About 68% of bacteria cells were transferred when the contaminated surface was wood, and less than 5% were transferred when the contaminated surface was carpet. So, you can probably eat that bit of dropped turkey meat with little chance of ingesting some horrible food-borne illness if your dining area is carpeted. The risks are higher if the floor is wood, and if it's tile -- well, I'd almost be tempted to don a haz-mat suit for Thanksgiving dinner at this point, just to be on the safe side. (Dawson himself says the study "demonstrates the ability of bacteria to survive and cross-contaminate other foods even after long periods of time on dry surfaces, thus reinforcing the importance of sanitation on food contact to minimize the risk of foodborne illnesses.")

Alternatively, I could invest in a spiffy new handheld spectroscopic detector for food inspection. Okay, such a thing isn't yet available for consumer use, and it hasn't been widely deployed on production lines in the food packaging industry, either, but the technology certainly exists, thanks to a group of researchers at the University of Manchester in England. Last year, they announced their new technique for food inspection based on infrared spectroscopy and software algorithms originally designed for genetics. They can identify spoiled meat in just 60 seconds, as opposed to the hours it usually takes using existing methods.

The new technique doesn't detect the bacteria itself, but the biochemicals produced when microbes break down food; when the concentration of bacteria reaches 10 million bacteria per square centimeter for chicken -- 1 million for beef -- they break down "nitrogenous compounds." The result: spoiled meat, with that distinct rotting odor familiar to anyone who forgets to clean the leftovers out the refrigerator for a few months. Handheld spectroscopic detectors are already being used to detect weapons and toxic materials, and the Manchester researchers are confident they can come up with a similar device to detect spoilage in foods -- even eggs or milk, which require a bit more sensitivity to the presence of pathogens. Andrew Proctor, a food sciences professor at the University of Arkansas in Fayetteville, is also using IR spectroscopy, in his case, to detect nerve tissue in minced meat, one of the factors implicated in the spread of mad cow disease.

So as you recover from the holiday meal, feasting on leftovers and taking advantage of the weekend sales to get a head start on your Christmas shopping, remember -- on top of everything else you're thankful for -- to thank science, for continually pushing the envelope of human knowledge to keep us healthy, well-fed, and safe from the marauding billions of microbes out there just itching to wreak havoc with our gastrointestinal tracts.

I'm especially thankful that the Acoustical Society of America is holding its fall meeting in Hawaii, this year, which is where I'm heading on Monday. Boeing can't put together its new anti-jet lag planes fast enough. But hey -- sun, sand and surf, baby! My next post will be from my Honolulu hotel. Aloha!

how (not) to murder your wife

Whew! I am back briefly in Washington DC after a 10-day trip to three different cities, and a whole lotta blogging in between. Thanks, as always, to Lee Kottner for ably filling in for me here at Cocktail Party Physics with excellent posts on Hubble, a space elevator update, and manned missions to Mars. And a warm, heartfelt thanks to everyone who commented, linked, etc. to offer well wishes and congratulations on my forthcoming change in marital status. After less than a year into my bloggy existence, it really made me feel part of the growing science blogging community -- although Jen-Luc Piquant rather snidely points out that the only post dealing exclusively with my personal life generated more hits and links than anything I've written about science. Being of a pretentious bent, she's dubbed our combined public persona "Seannifer," a la Brangelina and TomKat. (According to this rating system, Sean is an A-List blogger, whereas I am a B-list blogger. Cynical sorts might say that I am carrying on the Katie Holmes tradition of "marrying up" -- in this case, to promote my standing in the blogosphere. Pfft, I say. What's a Technorati ranking, anyway?)

Shiny new A-list fiances notwithstanding, the marital state is not without its perils, even if one's (future) spouse happens to be a physicist. Yesterday I stumbled across an article about a University of Alabama, Huntsville, physics professor who has been arrested for murdering his wife. Forty-five-year-old Andrew Pakhomov allegedly -- remember, innocent until proven guilty, people! -- strangled his 42-year-old wife, Yelena Zakin, with a braided brown leather belt and dumped her body in the Tennessee River after weighting it down with a bag of rocks.

The motive for the murder is murky. (The folks at Beatrice somewhat cynically point out that Pakhomov has a book coming out next August on the physics of plasma dynamics and ablative laser propulsion. However, we are doubtful that being accused of murder will substantially boost the sales figures for a highly technical reference book.) There was a history of domestic abuse in the marriage, a possible extramarital affair, and Zakin herself was arrested shortly before she disappeared, for assaulting her husband in the university's optics building when she found him in his office with a female colleague. Pakhomov's stepdaughter is on record saying that the couple's marital problems began when the physicist failed in his bid to chair the physics department.

It is, ultimately, a tragic tale, one that has rocked an otherwise peaceful academic community.  Pakhomov is currently out on bail, awaiting trial, and his lawyer maintains his client's innocence. Details regarding hard evidence in the case are sketchy, but police apparently found unspecified "forensic evidence" in Pakhomov's SUV, and the belt used to strangle Zakin was very similar to the one Pakhomov was wearing at the time of his arrest. The latter is decidedly circumstantial evidence; in general, prosecutors of homicide cases prefer more solid, scientific evidence: DNA samples, for example, or clearly identifiable fingerprints. (Yes, we watch C.S.I. And Law and Order. And even Bones, when time permits.)

Fingerprinting as a means of personal identification has a particularly long and colorful history. There is evidence that ancient Babylonians used fingerprints on clay tablets to ratify business transactions, while in China, thumb prints have been found pressed into clay seals. Persian official documents in the 14th century relied on fingerprint impressions, and one official noted that no two prints seemed to be identical. In 1686, an Italian professor of anatomy in Bologna named Marcello Malpighi noticed there were distinct ridges, spirals and loops in fingerprints, but it never occurred to him that these patterns might be unique to individuals, and therefore might be a good tool for identification. (The "malpighi" layer of skin was named after him, however.) A century and a half later, in 1823, another anatomist named John Evangelist Purkinje (of the University of Breslau) published a thesis detailing nine distinct fingerprint patters, but again failed to recognize their value as a useful identification method.

It was a 19th century English Chief Magistrate of the Hooghly district in Jungipoor, India, who unwittingly revived the ancient tradition of using fingerprints to "ratify"   contracts with the local natives in July 1858. At first, Sir William Herschel didn't intend anything more than to frighten a local businessman named Rajyadhar Konai so that the latter wouldn't be tempted to renege on the terms of their agreement, but the practice was so effective, Herschel soon required palm prints (and later the prints of the just the right index and middle fingers) on all contracts made with the locals. Apparently, they believed the personal contact with the document was magically more binding than a simple signature.

That was pretty much the extent of Herschel's contribution to fingerprinting, but he did notice that his inked prints could potentially be used for identification purposes. In 1880, Dr. Henry Faulds published an article in Nature about using fingerprints to establish identity, as well as using printer's ink to make print impressions. Faulds is usually credited with the first fingerprint identification, by analyzing the greasy fingerprint on a discarded bottle of alcohol. (It didn't take long for the practice to worm its way into literature. Mark Twain's Life on the Mississippi depicts a murderer being identified by his fingerprints, while in a later novel, Pudd'n Head Wilson, the central court trial rests on fingerprint identification.)

An Argentine police officer named Juan Vucetich made the first criminal fingerprint identification in 1892. Francisca Rojas murdered her two sons, then cut her own throat in a lame attempt to deflect blame on an unknown attacker. But she was sloppy, and left a bloody print on a door post, and Vucetich was able to prove she was the murderer based on the arches, loops, and whorls that made up her unique print pattern. Since then, the field has flourished and become a vital component of the criminal justice system. Today, the FBI maintains a database of more than 49 million digitized individual fingerprints called IAFIS.

As any diehard fan of crime shows would know, conventional methods for lifting fingerprints at a crime scene involve treating the samples with powders, liquids or vapors to add color to the print to enhance the contrast so it can be easily seen and/or photographed. However, some of the chemicals used to collect fingerprints can actually alter, contaminate or destroy them, particularly when lifting prints from unusual (e.g., highly porous) surfaces, such as fibrous papers, textiles, wood, leather, plastic, or even human skin. They can also damage other valuable forensic evidence like blood or saliva. Furthermore, chemical based methods can take hours or even days to process if the print needs any kind of contrast enhancement. (In one memorable C.S.I. episode, Grissom discovers that a previously hidden fingerprint on a matchbook "develops" over several months after being sealed in an evidence bag.)

Wouldn't it be great if crime scene investigators had a method for collecting print samples while leaving the print intact? There may be hope for Grissoms of the future. Scientists at Los Alamos National Laboratory have developed a new fingerprint visualization technique using X-rays that not only leaves prints intact, but can also reveal key chemical markers, thereby providing new clues for tracking criminals and missing persons. Chris Worley is an analytical chemist with the lab, who conducted the preliminary studies last year of the new technique to test its viability. It's called micro-X-ray fluorescence (MXRF), since it uses a thin beam of X-rays to irradiate a sample to reveal its elemental composition.

Scientists have long known that chemicals give off distinct "signatures," emitting or absorbing radiation at very specific wavelengths. Sodium, for instance, which is used in street lights, gives off primarily orange light, while the oxygen used in neon lights emits mostly green light. This effect is the basis for most spectroscopy techniques, which in turn enable astronomers to ascertain the chemical composition of distant celestial objects, for example. Pass light from a star through a spectrograph, and it will spread into an electromagnetic spectrum, much like visible light breaks into its component colors when it passes through a glass prism. Astronomers can then analyze how the spectrum becomes brighter or darker at each wavelength and determine which chemicals are present in the source star.

That same principle applies to earth-bound spectroscopic applications. For forensic fingerprinting purposes, salts such as sodium chloride and potassium -- commonly secreted in human sweat -- are of particular interest. Worley's group showed that the MXRF method can detect the presence of such salts (assuming they are present in sufficient quantities), and since those salts are deposited along the patterns in a print, it's fairly easy to produce an elemental image of that print for analysis. According to Worley, the method is especially promising for imaging children's fingerprints, which are more difficult to detect than adult's.

Worley and his Los Alamos colleagues aren't the only scientists grappling with the print preservation problem. Optics researchers at the University of Pennsylvania have devised their own light-based method for recording fingerprints without using chemicals or otherwise disturbing the delicate latent prints at a crime scene. Their method doesn't require X-rays, or much in the way of specialized equipment; just a standard light source, a polarizing filter -- similar to the ones found in higher-end sunglass lenses -- a digital camera, and a computer to process the collected data. You just need to shine the light on the fingerprint at a certain angle and position the polarizing filter in such a way that reflected light passes through it. The filter will then selectively darken either the background or just the outlines of the fingerprint. This increases the contrast, such that the print is more clearly visible against the background surface, so it is visible to the eye or the lens of a digital camera. There's a patent pending on the technique, and the scientists are now building a prototype portable version of the system.

So fingerprinting just gets better and better. Add DNA evidence to the mix, and it's pretty tough to get away with murder these days -- or even prankish Cyber-crime. For instance, Jen-Luc purportedly spent a wild weekend carousing in the virtual world Second Life, but the festivities were cut short by a marauding army of self-replicating virtual gold rings that overloaded the servers. I'm not accusing her of being directly responsible for this "grey goo" Cyber-scenario, but she has been known to use the CopyBot program -- a practice that hard-core Second Life users frown upon -- which performs a similar function. Where there's smoke, there's sometimes fire. Jen-Luc's virtual fingerprints could be all over this case....

to mars!

Say this to a physicist, you'll get one of two reactions: "Yeah, go for it!" or "Utter waste of perfectly good research funds." Say it to any science fiction fan and, depending on their age, one of several books immediately spring to mind: Edgar Rice Burroughs' A Princess of Mars, H.G. Wells' War of the Worlds, Ray Bradbury's The Martian Chronicles, or Kim Stanley Robinson's more recent Mars trilogy, Red Mars, Green Mars, and Blue Mars. All are ripping good yarns of space exploration and colonization, some more technically astute than others, some with a more cultural bent, some focusing on the foibles of the explorers. My favorite of this group is Bradbury's Martian Chronicles for its humanism. But my real favorite is one that seldom gets mentioned, by my old standby Robert Heinlein: The Green Hills of Earth. This is because it's dead romantic. And that should make the naysayers pay attention.

Before you all go "Yuck! What's that got to do with Science?", let me steal a minute from the admitted romance of Seanifer (or "Jean" as El Finster calls the happy couple) to remind you that science is an endeavor of exploration. Exploration is inherently romantic, whether its equipment is pipettes, positron emitters, or pitons. It often doesn't seem very romantic or glamorous when you're pipetting solutions, calibrating instruments, or clinging to a cliff-face thinking "I'm gonna dieeee!" And you know, it's not. Sweat is not glamorous, whether it's intellectual or literal. It's the discoveries that are glamorous, and that shine rubs off on both the discoverer and the slog that led up to it.

Exploration and discovery have more than just tangible benefits. More important than the actual knowledge or invention, sometimes, is just the fact of the attempt, including the ignominious failures before the final success. The thing about discoveries and exploration is that they're never just an individual effort. All those guys who get credit for being the first? They didn't get there alone. In the background pushing their buttocks up the mountain were loving wives and husbands, parents, Sherpas, earlier researchers, financial backers, grant agencies, universities, graduate students, journalists, poets, and novelists.

Yes, poets and novelists. Cue "The Green Hills of Earth." First printed in the Saturday Evening Post in 1947 and later collected as part of Heinlein's "Future History" stories in an eponymous anthology and later in The Past Through Tomorrow, "The Green Hills of Earth" uses one of the oldest of tropes, the blind minstrel, to give readers a snapshot of "spacer" culture in an age when Mars is settled, asteroid mining is common, and even Venus is being homesteaded. When I say this is an old trope, think Homer and the Odyssey. "Green Hills" has the same kind of helpless longing for home coupled with hopeless fate-driven wanderlust. It romanticizes the most exotic type of travel imaginable: into the unknown. There's a long tradition of exploration literature, of blind minstrels singing about mad explorers going off half-cocked and ill-prepared only to come home fabulously wealthy for having seen unspeakable wonders. The Old English poem/poet Widsith gives us a catalog of his traveling companions that includes Offa and Attila, and the Israelites and the Egyptians. Okay, so he exaggerates a little. Think of it as a metaphor. But before giving us his long list of travels, Widsith (literally "far traveled") says,

Therefore I passed through many foreign lands
and through spacious ground.  Good and evil
there I became acquainted with while my native country was remote,
tho my kinsman's spirit followed from afar.

It's that last line that sums up the importance of exploration. It explains why thousands of people line the streets of New York for the marathon every year to cheer on the runners. Every time someone attempts something extraordinary, whether it's a physical or mental feat, that attempt and the eventual success shines a little reflected glory on all of us, makes us stand up a little straighter, try a little harder, think a little more about what we might leave as a legacy. Great accomplishments inspire us. Every time there's a shuttle launch, I'm there in spirit screaming "Go baby go!" as the rockets fire because a part of me goes with its occupants.

Heinlein was a former naval officer himself and knew very well that the siren call of the sea was both a literal hankering for new sights and sounds, and a metaphor for the human restlessness and curiosity that drives the survival of our species (and sometimes seems to be helping us into extinction, along with the rest of the planet). "Green Hills" takes its title from a song written by "Noisy" Rhysling, the story's blind singer, one of the few tunes mentioned that Heinlein bothered to flesh out. It's Kiplingesque in style and tone, and yet not by any means doggerel. The stanza that always chokes me up is this one:

Out ride the sons of Terra,
Far drives the thundering jet,
Up leaps a race of Earthmen,
Out, far, and onward yet ---

It was the first thing I thought of when the Challenger exploded and again when we lost Columbia. Those two disasters are usually the strongest part of the arguments made against going to Mars. It's not safe. We don't have the technology. It's too risky. What crap! I'm sure that's been said to every explorer from Odysseus to Admiral Perry. In just over twenty years, we have lost two shuttles and their crews. For a sobering comparison, check the worldwide shipwreck list at Wikipedia. One database has documented 100,000 wrecks in North American waters alone over the last 400 years, an average of 250 per year. Safety is a poor argument to stay home. Most of us would never get out of bed if that were truly an issue, let alone leave the house. If you compare our levels of past and current technological sophistication, we basically went to the moon in glorified tin cans. What's stopping us now?

The waste-of-money part, perhaps? Look, we've all got our pet projects, our turf we want to protect, discoveries that are just around the corner, that need just a little more time and money to make, and it's never easy apportioning the limited dollars, especially in this grossly anti-science milieu. One way to counter this problem is to invite everyone else on board. I don't think the US should be the only ones going to Mars. It should be an international scientific commission planning it, and it should solicit commercial investment. For a start, talk to Sir Richard Branson of Virgin. He's into funding big new projects. He's already got dibs on SpaceShipOne's X Prize technology for Virgin Galactic. Mars seems like a good destination. And tourism is a great way to fund the scientific research bonanza that Mars colonization represents. Some of the best R&D has come out of commercial ventures like Bell Labs.

For that matter, we all know that some great developments have come out of the space program itself. I have a bad habit of thinking of space exploration as "pure" research, which it isn't. It's much more akin to applied research. Launching a rocket into space, getting it to its destination, keeping its crew alive and healthy while they explore, and then getting them home all present a series of problems to be solved. Many of those problems have applications to existing problems on earth, and have resulted in advances in everything from medical technology to new engine lubricants.

But again, that's not the main reason to go. The main reason to go is the view. Many of the Apollo and shuttle astronauts have talked about the effects of seeing the whole globe at once, and I've often thought it should be a requirement that any newly elected leader take a little trip into space to, uh, broaden his or her horizons. Talk about a radical change in perspective. It won't by any means solve all our problems, but it would be a sobering experience at worst. (And there's more than one politician I'd like to ship to Mars permanently. After a couple hundred years as a penal colony, maybe they'd all turn out okay after all, like Australians. And of course, there's all that inspiration, too, which I still maintain is the most important part of exploration.

So would I go?  In a heartbeat. After all, they're going to need somebody who knows from poetry and fiction. Besides, I figure it's my best chance of losing weight. Sign me up. I'm gone.

otherwise engaged

Life has a way of throwing you curve balls occasionally, just to keep you on your toes. Sometimes the twists aren't so pleasant, but then again, sometimes they lead you in an exciting new direction you might not have otherwise explored. Case in point: When I moved to New York City after finishing college in Seattle, I had no idea I'd end up writing about physics and related sciences for a living -- and that it would be the perfect career for me.

Something similar happened when I started a blog called Cocktail Party Physics back in February. Among the many emails I received welcoming me to the blogosphere was a friendly missive from Cosmic Variance's Sean Carroll. Sensing a kindred spirit, we struck up an intermittent email exchange, eventually meeting at the APS April Meeting in Dallas. It was an unlikely setting for love to bloom, but nonetheless, bloom it did.

I now find myself engaged to this very same Sean Carroll -- as in, to be married. (Sean's own blogannouncement is here.) Past dating advice to geeks notwithstanding, my new fiancee status is quite the novelty, and I'm still navigating the unexpected twists and turns of the new fork my Road of Life is taking. But I promise not to turn into Bridezilla: wedding frenzy will not take over the cocktail party. (Jen-Luc Piquant, on the other hand, has been reading far too many back issues of Modern Bride, and is losing her Cyber-cool just  a bit.)

Some may wonder: why Sean Carroll, and not some other bloggy physicist or science type? I could provide a laundry list of reasons stretching into infinity, since one rarely needs an excuse to sing the praises of one's beloved. But I'll spare my readers. Let's just say that the man has his very own bag of plush plagues, stuffed toys that represent the biblical ten plagues of Egypt. There's even a tiny black cube of darkness. With eyes. I covet Sean's bag of plagues, and figure the best way of sneakily appropriating them for my own is to enter into the bonds of matrimony. Community property and all that.

But the real reason is best illustrated by this: On Wednesday, after I'd finished my blogging duties at the Industrial Physics Forum in San Francisco, we drove to his new home in Los Angeles via the "scenic route" along the coast. At sunset, we stopped briefly to refuel and to admire the brilliant orange, red and purple hues stretching across the horizon, and savor the peaceful sound of waves lapping against the shore. It was the perfect romantic setting to cap off a long and tiring several days. Sean is nothing if not romantic. So he put his arms around me and whispered, "Wouldn't it be fascinating to take a Fourier transform of those waves?"

I will never listen to ocean waves or view a beautiful sunset in quite the same way again. He is always doing this, surprising me with an off-the-cuff observation, confronting my too-pat assumptions, challenging me to consider things from a variety of angles rather than the easiest or most obvious, and joyously inviting me to share his passion for discovering as many mysteries of the universe as we can manage in our comparatively short time here on earth. I can't imagine anyone else I'd rather have by my side as I take this new fork in my Life-road. Who knows where it will lead? All I know is -- I won't be bored.

the dark-adapted eye

Like many people, I breathed a huge sigh of relief when the news broke that Hubble was going to be repaired and rescued. In my opinion, this is one of the best decisions NASA has ever made, right up there with going to the moon, and developing the space shuttle. Hubble is probably the most beloved project NASA's ever had, literally outshining the Apollo project in the trove of spectacular images we have amassed from its gaze. If you want to turn kids on to science, there are few better ways than to show them some of Hubble's photos of the phenomena of deep space. For wow-factor alone, Hubble's cheap at twice the price, especially in this day and age of omnipresent light pollution. (Apropos of nothing and rather serendipitously, I'm listening to a 1926 recording of Holst's "The Planets" as I write this, and I keep waiting for Orson Welles to interrupt the broadcast with the news that Martians have invaded Earth. Of course, now the work will have to be titled "The Planets and One Dwarf Planet.")

<old fogey alert>When I was a kid, all I had to do was walk out the door and look up on a clear night to be completely overwhelmed and awestruck by the wonder of the night sky. Now, even though the neighborhood is not much more built up than it was in the 70s, all the new neighbors, and some of the old, insist on lighting their yards throughout the night. Former city dwellers as most of them are, they see danger lurking in the darkness, when in truth it's mostly raccoons, and the lights don't scare them one bit.</old fogey alert> This severely cuts down on the viewing pleasure in my former front yard. And now that I live in the City That Never Sleeps (which means it's much more the City of Lights than Paris could ever hope to be), I'm excited when I can actually manage to pick out a lone constellation somewhere, or even a particularly bright star (which is just as likely to be a satellite). Comet Hale-Bopp delighted me for the several months I could see it, especially when it appeared to be hanging directly over my house, coma erupting upward like a fountain. But most kids growing up now don't even know what they're missing in the night sky. Hubble is an excellent way to counteract some of that loss. But only some of it. There's no real substitute for getting out at night with a pair of binoculars, a small telescope, or even your nekkid eyes and looking up into the sky.

But doing that is becoming increasingly difficult, if not impossible, due to light pollution. The scale of the problem, ironically enough, is clear from the "before" and "during" pictures of the 2003 East Coast Blackout taken by NOAA satellites . During the blackout in NYC it was amazing to see the night sky smack in the middle of the city. It might almost have been worth the trek to the top of one of the high-rises to get roof access for a little stargazing. I'm sure most of us who live here have pretty much forgotten what the night sky looks like, embraced by the artificial glitter of neon and sodium lights. Light pollution is a serious enough problem that several international organizations and national advisory groups have formed to combat it, such as the International Dark-Sky Association. The Prairie Astronomy Club has some handy guidelines to help reduce light pollution in your own back yard, so to speak. I'm actually rather fond of Iceland's way of dealing with it, though.

Phil Plait scooped me on this ages ago over at Bad Astronomy, but it was such a brilliant (forgive the pun) idea, that I wanted to mention it again. For a half hour in September, all the streetlights in Reykjavik were turned off so people could get a clearer view of the sky. According to space artist Bjorn Jonsson who lives there, though, most of the light pollution is actually from other sources, not streetlights. I don't doubt this. Coming in over the city for a night landing at LaGuardia, streetlights are the least prevalent of light sources (though some of the most easily seen, especially in the middle of empty parking lots). Anyway, it's a great idea, and I'd love to see a voluntary half hour lights out, though that's unlikely in New York. But I wonder sometimes what we're losing with this disconnection from the night sky.

When I was starting to write this post, I noticed that Jennifer has categories for both astrophysics and cosmology, but not astronomy. Plain old visual astronomy seems to have lost some of its coolness factor, and morphed in much the way the study of literature has turned into literary theory. Theory seems to have much more attraction for the best and brightest than long freezing nights peering out at light collected through meticulously ground slabs of glass. Old fashioned visual astronomy seems to be drifting back into the domain of dedicated amateurs with their backyard telescopes, while the pros concentrate on radio astronomy in wavelengths not visible to the unaided human eye. Don't get me wrong: it's very cool stuff, bursting with new discoveries—like the 6-million-light-year-wide remnants of the ring recently spotted with the VLA—but for beauty and romance and sheer awe, I think it lacks something. "Listening" to space seems counterintuitive to me.

Or maybe not, now that I think about it. My dad worked on an Air Force flight line in Northern Michigan when I was growing up, and every now and then when he was working nights, our phone would ring after dark and Mom would come into my room, bundle me up in a jacket and take me out to see the Northern Lights at Dad's behest. Although the Aurora Borealis is technically an atmospheric phenomenon that occurs when the solar wind's electrons collide with atoms in the Earth's upper atmosphere, charging them and making them fluoresce, it was still part of the night sky show to me. Discovering later that it was the solar wind making those curtains of light ripple and hiss did nothing to detract from the sensation that a little of the night sky was falling to earth. And the fact that you could hear it . . . well, that was just too cool for words. And what that, and the other nights of stargazing in my yard, started was a life-long enthusiasm for space, which expressed itself in the usual geeky ways: membership in Star Trek fandom, a diet high in saturated science fiction, a fascination with science. It's the latter that's really important, of course, and this is where Hubble comes in.

Hubble is one of those great geeky toys that the public loves. They may not see the tangible benefits from it because astronomy, cosmology, and astrophysics are still very much sciences of knowledge for its own sake. It's hard to make the vast majority of people care about, say, the existence of gravitons, but show them a photo like this one (Planetary Nebula NGC 6543):

. . . and it's hard not to be amazed by what's out there in all that dark, whether that dark is dark matter, dark energy, or just the absence of light in familiar wavelengths. In educational value alone, Hubble continues to pay for itself, even with rescue missions to keep it going for another ten years. I don't think we could ask for a better ambassador between the depths of space and our increasingly night-blind selves.

P.S. Don't forget to see what Jennifer is up to over at the AIP Industrial Physics Forum blog.

mashup: physics, architecture, fiction

Me again, Lee Kottner, Skeptic and Stylist to the virtual Jen-Luc Piquant, filling in for her meat counterpart (if I may use a crude cyber term) while she's off blogging elsewhere in a more professional and less casual fashion (i.e., AIP is paying her to do it). I thought I'd use this opportunity to get back to you about the Space Elevator project over at LiftPort and pimp a couple of my new favorite blogs at the same time. At first glance, the space elevator, BLDGBLOG, and Pruned don't seem to have much in common with each other. But you'd be surprised how often physics crops up on a couple of blogs ostensibly devoted to, on the one hand "architectural conjecture, urban speculation, [and] landscape futures" and "landscape architecture and related fields" on the other.

Take this post at Pruned, for instance, a pictorial tour of images from NASA's heyday, when they were still dreaming big of colonies in space. The Pruned images are of cylindrical colony designs, but there are also toroidal designs similar to Larry Niven's Ringworld that I wrote about here earlier. And there's an interesting little link in this post to another called The Physics of Space Gardens which speculates on a new kind of "hanging garden" (perhaps for a new, space-borne Babylon?). Then over at BLDGBLOG, there's Sun's Project Blackbox, an extremely powerful, self-contained datacenter built in a shipping container. Geoff Manaugh speculates that these might be the seeds of Archigram's "computerized instant cities and other 'plug-inscapes'." Shades of Neal Stephenson's Cryptonomicon, where the characters are engaged in (among other things) creating an offshore "data haven" similar in concept to what offshore banks provide.

I'm often intrigued by the kind of chicken-and-egg problem presented by science fiction, and the way in which the ideas and developments of science influence the rest of the culture in unexpected and sometimes completely off the wall (though not necessarily superficial or stupid) ways. You can see that influence in both of these blogs, which often talk about the development of new materials such as the pollution-eating tiles coated with titanium dioxide, or about cosmological phenomena, or the repurposing of already existing materials and structures, or various posts about geology, human reactions to it, and its tools. It's the intersection (or sometimes the collision—known as a mashup in current parlance) of pure and applied research and wild speculation that makes for interesting developments in art and culture, as well as other research fields, and sometimes it's hard to tell which came first.

This is especially true of projects like the space elevator that are so ambitious and daring as to be almost preposterous. Like going to the moon, building and operating space shuttles or even, at one time, insisting on sailing west from Europe to India, visionary ideas invite scorn (often deservedly). They require not just a leap of imagination, but a shift in perspective and focus and sometimes this transformation in thinking is eased a bit by being introduced as fiction, a medium where we're already less reluctant to suspend our disbelief. Because the space elevator is still deep in R&D territory, it's not a bad idea to mix in a little well-written and well-researched fiction to round out the picture.

And this is what the mashup, LiftPort: Opening Space To Everyone, does. It's also what makes it interesting. Brian Dunbar over at LiftPort very kindly sent me a copy after my last post here and while I haven't read it in depth, I've been thumbing (or scrolling in this case, since it's a PDF) through it in a strictly unsystematic way. The anthology—edited by Michael J. Laine, Tom Nugent and Bill Fawcett of Liftport—is a mix of boosterism (and I don't mean that in a bad way), technical discussion, and science fiction (and I don't mean that in a bad way, either). The technical information is supplied by people like Dr. John LoSecco of Notre Dame, Dr. Arthur Smith of APS, who is also a vice president of the National Space Society, Dr. Jordin T. Kare, formerly of Lawrence Livermore National Lab and NASA's Institute for Advanced Concepts.

The collection is a work of imagination of the best kind: taking scientific principles and imagining how they could be applied in a practical yet creative way and what that development might mean to humanity. The book attempts to cover all the bases, anticipating and answering questions about everything from finance and safety, design and construction, legal, military, environmental, and sociopolitical issues, to what the elevator might actually haul into space. Interspersed with expert essays that, although for a general reader, still sometimes read like business reports is some intriguing speculative fiction on the subject by Arthur C. Clarke (one of several originators of the elevator as a concept along with Charles Sheffield, whose fiction about it also appears here), Kevin J. Anderson, Jodi Lynn Nye, David Brin, and others. Reading Sheffield and Clarke, you get a clear picture of how the fiction inspired the research; reading the technical and economic reports you see how those ideas influenced the later fiction. This book is the kind of primary document a historian of science or cultural historian will eventually have a field day with.

The conceptual integration is by no means seamless. No single picture of what the space elevator should do (apart from go up and down safely) emerges from the volume, but this isn't necessarily a bad thing. The space elevator is a primary sort of tool, a bit like the wheel. Once we make one and see how handy it is, no telling how many other uses we'll find for it. Its development embraces many disciplines—engineering, socioeconomics, geopolitics, materials science, even architecture, and many of those areas are going to overlap or conflict or both as development goes on.

The biggest service this collection performs, and it does so with the help of the fiction it includes, is to make the whole project seem plausible and even realistic. In fact, it seems far less freaky than the anti-global warming sun umbrellas over at BLDGBLOG, a project that, come to think of it, would probably benefit from the development of the space elevator. So would Pruned's extraterrestrial cemetery, which seems a little weird to me, too. But 50 years from now, when the space elevator is a quarter of a century old, maybe none of this will seem so bizarre.

nano nano

Jen-Luc Piquant and I are heading off this afternoon, but we're each going our separate ways. She's, well, going to do whatever avatars do in Cyberspace for "down time." Don't ask, don't tell, right? I am en route to San Francisco for the 2006 Industrial Physics Forum, on nanotechnology in society and manufacturing. It's being held this year in conjunction with the annual meeting of the American Vacuum Society. That's "vacuum" as in "Nature abhors a....", not as in a Hoover, for all you smart alecks out there. And yes, it's a common misunderstanding. One year, the AVS memorably offered stickers with a Hoover inside a red circle with a line through it, a la Ghostbusters. Clearly some staff member got tired of fielding phone calls from people in need of home appliance repair and sought catharsis through merchandising. (Jen-Luc heartily approves.)

Anyway, in an interesting twist, I'll be live-blogging the meeting on behalf of the American Institute of Physics, which organized the IPF each year. They've set up a separate blog for me and everything, and you can see my first introductory post here. [SECOND UPDATE: Linkage problem solved! The problem with the link is, there needs to be a backslash at the tail end of the address, like so: http://blogs.physicstoday.org/industry/]. Bookmark it, and check in regularly beginning Sunday evening through Friday for some of the highlights of what promises to be a fascinating few days. The posts will be much shorter (that's the idea, anyway, although it has been pointed out to me that I have a real problem with writing short), pithier, and -- sadly -- a bit less snarky, given the absence of Jen-Luc Piquant, but it won't be your usual boring meeting recap either. And they'll be more frequent, as in, two or three times a day. Comments and trackbacks will be enabled, so hopefully we can get some discussion going as well, on the science, ethics, policy issues, or random trivia surrounding nanotechnology -- whatever comes to mind. It's certainly a rich topic for debate. (Comments will be moderated, but I'm pretty easy with the delete button, so long as everyone plays nice.)

This is a new approach for AIP, and I'm really excited about participating, even though it means I'm going to be absolutely crazed the entire time. It'll be worth it. A lot of organizations are skeptical of blogs and their ability to reach the target audience, disseminate information, or what have you. We all know differently, and if this fledgling venture proves successful, perhaps AIP (and other scientific societies) will consider doing more of them. So I hope my fellow science bloggers, among others, will check it out and link to it, if they do desire. That is my not-so-subtle hint at self-promotion. (Jen-Luc Piquant was all set with a bullhorn, but I told her that wouldn't be necessary.) In particular, there's numerous nanotech-specific blogs who might be interested: Advanced Nanotechnology, Nano Public, Nanotech Buzz, Responsible Nanotechnology, Nanotech Law, Nanobot, even a blog by the Foresight Institute's Christine Peterson. And those are just the ones whose names begin with "nano."

What about Cocktail Party Physics? You may be wondering. Lee Kottner will be ably filling in yet again for the next week, until the madness of the IPF live-blogging experience is over. She's got several terrific posts in the works -- I cheated and took a preview peek -- including an update on the space elevator and the Mars program. Jen-Luc Piquant and I will be back in 10 days, with a new batch of fun and fascinating posts of our own. Au revoir!

let them eat cake

On my niece Kathryn's first birthday, she experienced cake for the very first time. Having lived primarily on breast milk and pureed baby food up until then, she had no idea the kind of succulent sweetness that was in store when the round, chocolate-frosted concoction was placed before her, a single candle burning in the center. She learned fast, though: when that first taste of frosting touched her lips, a look of awed wonder spread across her cherubic toddler face. Then she literally buried her face in the remaining cake to wallow in this newfound gastronomic delight -- to the horror of her mother, who had neglected to explain that birthday cakes are meant to be shared by the entire family. (I could post photos, but I've embarrassed my niece -- who is now 14 -- quite enough for one day.)

Children, needless to say, are not big on sharing; my nieces and lone nephew are no exception.  It was a cruel blow when they learned they must share, and they responded as all kids do: by becoming experts in measuring down to the last crumb exactly how big (or small) a given slice of cake might be. Every parent has had to deal with the pained cry: "But his piece is bigger than my piece!" And no amount of rational  explanation will convince said child otherwise, or assuage their sense of being deeply wronged or slighted. 

I was surprised to learn this past week that kids might have a point: it can be quite difficult to divide a cake perfectly evenly, particularly if size is not the only variable. In fact, it's a well-known, knotty mathematical conundrum, with some practical implications extending beyond negotiating childish disputes over equitable division of cake. In a paper to be published in the December 2006 issue of Notices of the American Mathematical Society, Steve Brams (New York University), Michael Jones (Montclair State University) and Christiam Klamler (University of Graz, Austria) uses mathematics to suggest a new strategic method for the equitable division of delicious cake. (The men specialize in political science, mathematics and economics, respectively -- a truly interdisciplinary collaboration.) 

A pdf of the full paper is available at a non-public Website, which I don't feel comfortable linking to here; it is supposed to be non-public, after all, and we try to respect boundaries here at Cocktail Party Physics. Try contacting the American Institute of Physics Public Information office if you want more details. I'll just provide a brief outline of their argument here.

To wit: if a cake must be evenly divided between two (clearly gluttonous) people, the most common method since time in memorial is the "you cut, I choose" approach. Let's say, for example, that Jen-Luc Piquant must share her after-dinner cake with her Cyber buddy, Kimba. How can she ensure she gets her fair share (especially since Kimba -- a.k.a., the Human Hoover -- already devoured the lion's share of the preceding meal)? Deploying the "cut and choose" method, she cuts the cake and Kimba gets to choose the piece he most prefers. This gives her great incentive to cut the cake as evenly as possible, knowing that he will most likely choose the biggest piece for himself. Or will he?

As with most things in life, it's rarely that simple. The primary advantage to the cut-and-choose approach is that it is "envy free": neither person envies the other's slice because they each know they have received at least half of the cake. But Brams et al. point out that this assumes both parties have identical values -- that is, they are both angling for the largest slice of cake they can get in the negotiation. But values are highly subjective: what if Kimba actually values the slice with more (or less) frosting, or Jen-Luc would be willing to opt for a smaller slice provided she gets the marzipan rose decoration? Or what if the cake has half chocolate, half vanilla icing, and Kimba vastly prefers the chocolate? In those cases, equitability is not so easily defined.

Brams and his cohorts propose an alternate cake-cutting method, which they call "Surplus Procedure" (SP). Using SP, Jen-Luc can cut the cake in such a way that the value she places on her piece is approximately the same as the value Kimba places on his piece -- possibly with the result that both might feel they are making out like a bandit and getting 65% of their heart's desire. It all comes down to perceived value.

Of course, it gets a bit more complicated if the cake must be divided between three people: say, Jen-Luc, Kimba, and La Belle Chanteuse (whose real-world alter ego goes by Peri). For that problem, Brams & Company devised an extention of SP, called "Equitability Procedure" (EP) which ensures that everyone gets, say, 40% of what they want, based on their respective values. Beyond three people, though, the likelihood of achieving both equitability and envy-freeness becomes much less likely. (I should probably note that the actual conundrum is achieving equitable division with the least number of cuts: say, a two-person/one-cut, or three-person/two-cut strategy. Beyond four "players," apparently, there is no known procedure that will result in an envy-free division of a cake unless an unbounded number of cuts is allowed.)

Among the other practical applications of the SP method: fair division of land. if Jen-Luc values waterfront property and Kimba values land at the edge of a forest, the SP method will yield a solution that lets them divide the land in such a way that both will ultimately place the same value on their respective parcels of land. "We're proposing a new, more scientific approach to dispute resolution," Brams says in the official press release for the upcoming paper. "Even if it is not directly applicable, the reasoning that goes into fair-division algorithms is valuable. It shows how mathematics can contribute to making dispute resolution more rigorous and precise."

Brams knows of whence he speaks: he's the co-author (with Alan D. Taylor) of The Win-Win Solution: Guaranteeing Fair Shares to Everybody, which describes a broad range of contexts where fair-division algorithms can be applied. It's not just about birthday cake: the Camp David peace accords and the divorce of Donald and Ivana Trump are among the more notable examples. New York University has actually patented one of Brams' algorithms (the "adjusted winner" algorithm). Patents: they're not just for computer algorithms anymore!

The cake-cutting method appears to be a subfield of game theory, a branch of applied mathematics and economics devoted to the study of situations in which "players" choose different actions in an attempt to maximize their returns. Survivor adopts something of a game theory approach, although expertise in that does not guarantee a win; the primary attribute one needs, judging from the various seasons, is to be a manipulative sociopath. (Interestingly, both SP and EP are "strategy proof," according to Brams. The players can't manipulate the procedures to their advantage.) The most famous example is the "Prisoner's Dilemma," in which two partners in crime have been arrested and placed in separate cells, and offered the chance to confess the crime. There's an extensive matrix of expected payoffs, depending on each scenario each player might choose. It's too complicated to explain in depth in a single post, but you can read more about game theory here, and a bit about its long, colorful history here.

So the next time you're at a party, and it comes time for the cutting of cake, think about divvying things up in terms of "envy-freedom" and "equitability' -- just for giggles. If the subjective values of the partygoers all rest primarily on the size, it'll be vital to divide the cake into perfectly equal slices. To make your job easier, Kitchen Fantasy offers an eight-slice cake and pie divider, which promises to create perfectly equal 10-3/4 inch slices of cake every time -- for only $19.99. It could be the answer to all your cake-dividing woes... at least if they only involve eight party guests.

 

under pressure

Phase transitions are quite possibly one of the most fascinating areas of physics: different substances behave differently at various temperature and pressure points -- sometimes in very remarkable ways. Yet it's easy to lose one's sense of wonder, because we see phase transitions around us every day. Water boils, ice melts (diluting the taste of one's otherwise killer cocktail) -- no big deal, right? Wrong. Sure, you can produce a phase transition of sorts for just about any common material, but there's still a lot to learn about the underlying physics.

Case in point: Earlier this summer, an article appeared in Physical Review Letters (July 7, 2006), describing the results of a new computational study by scientists at Sandia National Laboratories indicating that a new conducting form of water -- dubbed "metallic water" -- could occur at a temperature of 4000 degrees Kelvin and a pressure of 100 gigapascals. Can we just say... yowza! Those are some high temperatures and pressures! And yet they are much lower than previous theoretical estimates calling for temperatures of 7000 degrees Kelvin and 250 gigapascals. (Confession: We do not actually know what a gigapascal entails, but we like the sound of it, and anything with "giga" as a prefix isn't exactly small.)

I meant to write a blog post about this whole metallic water business back in August, but as often happens, time got away from me. Also, the news broke while I was vacationing in Buenos Aires, so I was rather late in the game. My notes have been sitting in the blog fodder file ever since. Fortunately, I have a second chance to address the topic: the same researchers were on hand to present an update on their paper at the annual meeting of the APS Division of Plasma Physics, held this past week in Philadelphia. The authors -- Thomas Mattson and Mike Desjarlais -- summarized their earlier findings from their quantum simulations, which were sufficiently different from previous calculations to warrant some significant alterations in the standard theoretical phase diagram for water under such extreme conditions. (A phase diagram, for non-scientifically inclined readers, is just a graphical representation of the effects of pressure and temperature on the phase of a substance. Go here to find out how to build your very own phase diagram from scratch. We make our own fun here at Cocktail Party Physics.)

Residents of Washington, DC, might assume "metallic water" refers to things like high lead levels in the drinking water, when in fact it describes a form of water that is electrically conductive. It wasn't immediately clear to me what's so special about this, since water is pretty conductive in its normal state, but Jen-Luc Piquant reminded me that very high temperatures and pressures can give rise to new and intriguing properties for even a common substance like water -- in this case, ultra-high energy densities. How high? Far beyond those that would occur naturally anywhere on earth. In fact, it would take temperatures and pressures on a par with those believed to exist in the interiors of the gas giant planet Jupiter to produce equivalent energy densities in a lab like Sandia's Z-pinch machine.

We should have known this was coming. Back in 1996, William Nellis, a scientist at Lawrence Livermore National Laboratory, announced the successful achievement of metallic hydrogen, which, among other things, gave us some fascinating details about the compressed interior of Jupiter. (You can find out more than you probably ever wanted to know about metallic hydrogen here, along with some really nice graphics.) Hydrogen as we know it is a gas, but on Jupiter, it's believed to exist as a super-hot liquid metal because of the extreme pressures and temperatures that typify that planet. Eugene Wigner predicted back in 1935 that if you squeezed hydrogen gas hard enough, it would eventually metallicize, but the requisite pressure was so intense that physicists weren't able to achieve it for 60 years. Hydrogen being a primary component of water, it stands to reason that one day physicists would move on to exploring the possibility of metallic water. (Jen-Luc loves the fact that both these phases are known as "degenerate matter." Clearly the term means something completely different in physics.)

The usefulness of these new results isn't limited to the far reaches of our solar system. The whole point of doing the quantum simulations in the first place was to better understand the conditions deep in the heart of the Z machine, which emits incredibly powerful X-rays in very short (nanosecond) bursts -- the equivalent of many times the electricity generation of the entire world. Sandia uses water both as an electrical insulator and as switches. Zap water with that much electricity, and you'll vaporize it, causing the surrounding water pressures to rise as the resulting shock wave spreads outward. The Z machine exploits this effect to achieve its impressive X-ray energies.

The operators send electrical pulses of about 20 million amps through the row of water switches. Initially, the water acts as an insulator, but eventually it's overcome as the incoming charge builds up. At that point, the water transmits the pulse, in the process shortening (or compressing) it from microseconds to nanoseconds. Voila! Extremely high temperatures and pressures ensue, in the form of a really, really big "spark." The Z machine is undergoing a major upgrade, and Sandia scientists want to understand how their water switches work at deeper, "first principle" levels, so they can attain the optimal transmission of electrical pulses in the future. In the same way that one can never be too rich, or too thin, physics experiments can never really be too high in energy -- because higher energies invariably translate into discovering new and interesting physics.

Sandia's on a roll these days when it comes to weird temperature and pressure phenomena. Also on hand in Philadelphia this week was Sandia scientist Marcus Knudson, who uses strong acoustic shock waves to melt diamond -- more precisely, to determine its melting point. Diamond is one of the toughest substances known, standing its ground in defiance of all manner of onslaughts, but apparently it goes weak at the knees when confronted with the dulcet tones of Knudson's sound-speed technique. Okay, the tones are hardly dulcet: Knudson and his colleagues are producing acoustic shock waves with strengths between 6 and 10 Mbars, producing a mixture of molten carbon and solid diamond. I'm casting about for an appropriate analogy that a non-scientist can relate to, and coming up empty. Suffice to say that melting diamond completely requires shock waves stronger than 10 million times earth's atmospheric pressure.

Why does this happen? Just like with the Z machine, the shock wave transfers large amounts of energy to the diamond material when it strikes, increasing not just the pressure, but also the temperature. If the shock wave is powerful enough, the temperature will get so high, the diamond will begin to melt into liquid carbon. The Sandia scientists determined the "melting properties" of diamond by measuring the speed of sound in the shocked material. Basically, the strength of the sound wave correlates pretty neatly with whether the material in its shocked state is in solid or liquid form. They observed a steep drop in sound speed at the 6 and 7 Mbar levels -- a sign the diamond was beginning to melt.

Knudson's work is  particularly relevant to continuing research on inertial confinement fusion (ICF), which requires a material like diamond or beryllium for the fuel capsules used to produce fusion. For ICF purposes, a low melting point is desirable. So diamond's high melting point is a bit of a disappointment in that respect: beryllium has similar properties, but a lower melting point, making it the preferred material for ICF applications.

And here's another fascinating temperature-related tidbit gleaned from the pages of an upcoming issue of PRL: slo-mo boiling. Vadim Nikolayev of the Ecole Superieure de Physique et de Chimie Industrielles in Paris thinks he can explain why certain industrial heat exchangers -- such as those commonly used in power plants -- occasionally experience a "boiling crisis." [Hat tip: AIP's Physics News Update] That's what happens when the steam gets so intense, the machines actually, um, melt. (Jen-Luc shudders to think what might happen were the heat exchangers subjected to the Sandia team's acoustic shock waves.) It's a bit like what happens when a water droplet hits a hot frying pan: it evaporates very slowly. Boiling is generally considered a form of accelerated evaporation by scientists who study the phenomenon, characterized by highly efficient energy transfer: energy moves from a heater to a liquid via the formation of vapor bubbles. Things get dangerous when the temperature gets too high: so many bubbles form that the entire heating element gets covered in a vaporous film,  preventing the liquid above from absorbing heat. So heat builds up, and the machine melts down. You can see the process in action here.

Scientists know that much, but they still don't understand the "boiling crisis" problem sufficiently well to devise effective counter-measures. Enter Nikolayev and other colleagues from the Commission of Atomic Energy in Grenoble and the University of Bordeaux. They simulated the boiling crisis to test a theory that the meltdown occurs as a result of vapor recoil. Just like the thrust from a rocket blast, a bubble will grow under intense heat and push aside any liquid near the heating element, giving rise to that dangerously insulating layer of vapor. Subsequent experiments confirmed the theory. The cool thing -- literally -- is that those experiments weren't performed at skin-blistering temperatures, but hear the critical temperature of liquid hydrogen: 33 degrees Kelvin. That's because boiling at normal thresholds is so rapid, it's difficult to make precise observations. At 33 degrees Kelvin, boiling happens much more slowly. And since the laws of fluid dynamics are universal, they should be able to extrapolate the same basic principles of behavior all the way up to fluids at 100 degrees Celsius.

Similarly, the lessons learned for large-scale industrial plants can be scaled down to the individual consumer level, perhaps to address the "boiling crisis"that occurs in, say, in exploding laptops. And you should definitely care: the smaller those electronic components get and the more densely they're packed, the higher the rate of heat dissipation will be. Heck, my spiffy new MacBook Pro is a great machine, but I've noticed that it does run a bit hotter than the older Power Book That Died (when the hard drive had a meltdown). I've invested in a "portable insulated laptop computer desk" (a.k.a., the Lapinator) accordingly, which mitigates the problem a little. At least it hasn't exploded or caught on fire. Yet.

There is a point to this typically lengthy and rambling post, if you recall: Phase transitions are cool. (I didn't say the point was especially profound.) They are still, centuries later, giving rise to cutting-edge science -- like telling us more about the composition of Jupiter, or the potential for achieving a practical fusion energy source -- and yet also helping human beings stay cool as they obsessively blog and surf the Web. So thanks, Sandia scientists, Dr. Nikolayev (and cohorts)!