Cocktail Party Physics

physics is fundamental

Those forward-thinking SciBlings at ScienceBlogs have decided to put together a series of posts outlining basic concepts in their respective fields; judging by this recent article in the New York Times, their project seems particularly timely. Admirably representing the field of physics, Chad of Uncertain Principles has written two already, on the concepts of force and fields. We here at Cocktail Physics are always ready to jump on the proverbial bandwagon. And since there was a general call for input, we have compiled our own version of a Top Ten list: in this case, the Top Ten Things About Physics We Wish Everyone Knew -- because it would make the job of communicating scientific results so much easier, for scientists and science writers alike, if we didn't have to waste precious column inches constantly re-explaining what should be part of everyone's scientific background knowledge. Dare to dream, my friends! 

I'm admittedly biased towards broad concepts, rather than pointlessly memorizing lists of facts. Those facts are important, but it's tough to hold all that information in one's brain, ready to spew forth with an impressive recitation of facts on the offchance you run into one of those pesky polltakers trying to gauge the "scientific literacy" of John/Jane Q. Public. I'll grant that some members of the public are shockingly ignorant about science. But I also recognize that if you're just walking along the street, minding your own business, musing about what the real cause might be of the Cameron Diaz/Justin Timberlake breakup, and someone comes up to you with a microphone and video camera asking you about random scientific facts, it's pretty easy to have a temporary "brain fart" and blurt out something incredibly stupid. (Not that this has ever happened to me... ahem... Well, there was a recent instance where I accidentally referred to a famous Edgar Allan Poe short story as "The Cask of the Armadillo," which is inexcusable for a former English major. Damn you, Cameron and Justin! )

Since Chad's already covered forces and fields (Newtonian mechanics, inverse square laws, etc.), we can omit those key concepts; otherwise, they'd definitely be in the Top Five. And I'll assume that Chad will get around eventually to explicating electromagnetism and related topics. We can also leave out a bunch of basic "laundry list" kinds of things, which could be addressed by putting together several handy charts for future reference: the confusing array of physics acronyms, units of measurement, elementary particles and where they fit into the Standard Model, a metric conversion chart, etc. So, given those initial boundary conditions, here's my working list:

1. Let's start out with the "Duh" concepts. (Oh, stop rolling your eyes!) I'm always surprised by how many non-scientists don't fully grasp the scientific method, specifically, what is a theory versus what is an hypothesis. I think this is generally pretty well covered on ScienceBlogs from time to time, so perhaps a "basics" post could summarize those arguments in one place, and extend the discussion to incorporate the question of what constitutes scientific evidence. How do we know when something is true, or false? The reason many otherwise well-meaning people often fall for the ID-ists' fallacious arguments is that they can't tell the difference between the fake "evidence" cited by, say, The Discovery Institute, and actual scientific data.

This was brought home to me a few years ago at a Christmas party. I struck up a conversation with a clearly intelligent, educated party guest, who didn't run off screaming when he found out I wrote about physics. Instead, he asked about the cold fusion controversy, specifically, how mainstream physicists could write it off so resolutely. For comparison, he pointed to the discovery of the top quark. To him, there was no difference between the evidence cited for cold fusion and the evidence that led us to conclude we'd found the top quark, so he couldn't understand why physicists refused to give proponents of cold fusion the benefit of the doubt. Promulgating a more thorough understanding of what is and is not evidence could go a long way toward clearing up such confusions.

2. What the heck is a "function," anyway? This came up during my first few calculus lessons (and yes, I will be getting back to learning and posting about calculus once my life slows down a bit). It's one of those concepts that is so basic, and so fundamental to anyone in just about any science, that it's not viewed as jargon in the scientific community. Ergo, nobody ever bothers to actually define it in plain English. And yet it is absolutely critical to almost anything related to scientific research. It's easy to look up and memorize the textbook definition, but that doesn't necessarily convey genuine comprehension. Concrete examples help. Once I delved a bit into the matter, I found that actually, I did know about functions, in a conceptual sense. It just never occurred to me that this was the technical term for it. I suspect the same is true for other nonscientists, so making that connection clear would bridge that particular communication gap quite nicely. While we're at it, a more layperson-friendly explication of "vector" would be helpful, too.

3. Frames of reference. Yet another bit of jargon so common to scientists, they forget that the phrase might not hold any real meaning for John/Jane Q. Public, even though it's a fairly simple concept. It's still necessary to define the term. Chad touched on this in his post on forces, but it's central enough that it bears repeating. For instance, it's tough for a nonscientist to grasp why scientists occasionally argue about centrifugal versus centripetal force without a solid grasp of frames of reference. It's just as critical when considering the differences, physics-wise, between linear and rotational motion, and to understanding why Einstein's theory of special relativity was such a revolutionary advance.

4. Statistics and probabilities. The former is, admittedly, more of a mathematics concept (which I'm sure will be addressed on Good Math, Bad Math, if it hasn't been already), but with all the studies and polls and other statistically-heavy news stories wafting about ether these days, a better understanding of what those numbers mean, and how they can be skewed to mislead (or outright lie) could help alleviate some chronic misunderstandings among non-scientists about the numbers can and cannot tell us. Also, what do scientists mean by probabilities? What are the odds of aliens landing in Texas versus the Large Hadron Collider producing a mini-black hole that destroys the universe? And can a better understanding of probability make me a better poker player? (Short answer to the latter: Probably, if you take the long-term view.)

5. Sizes and Scaling. First, let's tackle the jargon problem: Just what the heck is an order of magnitude? I use the phrase all the time now, after years of hanging around physicists, but as a budding science writer, I found the term a bit opaque, and I'd wager the average person on the street is a bit unclear on the specifics, too. Second, this is one of those areas where a picture really can be worth a thousand words -- or, barring that, it helps to paint a word picture. Many science museums use the "powers of ten" approach when discussing various size scales in the universe, from the subatomic level to the farthest reaches of the universe. It's been around since at least the 1960s, and it endures because it's effective. But it's just a start. The laws of physics actually start to change as one approaches the subatomic level, and a clear explication of how size and scaling can change a system's behavior would help with the public's chronic confusion about a number of things, like...

6. ... quantum weirdness. Normally I'd include this under "advanced concepts," but the huge success of that New Age piece of nonsense, What the (Bleep) Do We Know?, aptly illustrates John/Jane Q. Public's need for a better, more nuanced understanding of quantum mechanics -- particularly the fact that while strange things can and do happen in the subatomic world, that doesn't mean they can happen in our daily existence at the macroscale. Example: Just because empty space is constantly churning out virtual particles that wink in and out of existence too rapidly to violate basic energy conservation, that doesn't mean that bunnies made of cheese will magically pop into existence in your backyard. Nor does it mean that saying cruel things to a glass of water will hurt the feelings of its "molecules of consciousness." If there's a way to talk about this without raising the specter of decoherence, so much the better. Part of the problem is that the subject doesn't lend itself to snappy sound bites; I recently stumbled all over myself during a radio interview in Seattle, trying to sum up quantum teleportation in two minutes or less, and I'm supposed to be good at this communication stuff. Still, the widespread misunderstanding of the Uncertainty Principle alone makes better explication of the subatomic subtleties absolutely critical.

7. Thermodynamics. I think many people have at least an intuitive understanding of certain aspects of thermodynamics, because it so directly impacts our daily existence. We know our coffee cup cools until it reaches equilibrium with room temperature, we know that even the best batteries don't run indefinitely without recharging, and we know that if we unplug the refrigerator (or if there's a power outage), eventually heat will seep into the chilled interior and spoil any food left inside. We know this from experience. But we keep falling victim to wishful thinking when it comes to perpetual motion or "free energy" schemes. Somehow, the public doesn't seem willing to accept that the second law of thermodynamics isn't likely to be violated any time soon. We can't in fairness ask them to take our word for it, and then criticize them for a lack of critical thinking, can we? So we must continue to make the case, each time patiently pointing out that really, we're not dismissing the prospect out of hand, we've just tested and re-tested to the nth degree. (See #1 about what constitutes scientific evidence.) It's tiresome, but these issues keep cropping up, so there should be a ScienceBlogs "basics" post about it.

8. Phase transitions/molecular structure. What's important here is how changes in temperature and pressure can have transformative effects on things, and how materials derive their properties (including "phase") from how their atoms are arranged. Again, we see these kinds of things on a daily basis: anyone who's tried to bake a cake at high altitudes has experienced  how changes in pressure and temperature can affect a substance. But if you're compiling a bunch of posts on the basics, I don't see how this could be left out. Materials physics is central to pretty much all of modern technology, after all.

9. A primer on accelerators. I'm not trying to single out one field of physics above all the others, but accelerator physics has been in the news quite a bit of late, and with the LHC beginning operation soon, it's going to continue to be in the news. And the news isn't always positive; note my comment above concerning the mini-black-hole hysteria. That sort of public "concern" stems from an incomplete understanding of what's going on, but there's so much basic physics that has to be grasped first before it's even possible to have a helpful discussion of why such a thing is incredibly unlikely. Most people can readily grasp the "smashing atoms" part, and Joanne at Cosmic Variance recently wrote an excellent post on Detectors 101 that makes for a handy supplement to any primer on accelerator physics. But -- and this gets back to the scale and sizing thing -- it's not apparent to the average non-scientist that what might seem like a fairly small amount of energy at the macroscale becomes significant when compressed into a tine subatomic particle like the top quark, so an explanation of why this is so would be helpful. And it's not clear to most non-scientists why size matters when it comes to how long black holes can hang around before evaporating out of existence.

10. Connecting the dots.I've had several conversations with Future Spouse about the need to make crucial connections between the various areas of physics. The concepts outlined in 1-9 above don't exist independently of each other in a vacuum; they are part of a seamless whole that, taken together, provides a reasonably elegant explanation of how the world works, why some things can happen, and other things can't. Case in point: Future Spouse likes to point out that understanding that, in order for a perpetual motion machine to exist, it must violate not just thermodynamics, but several other major physics theories as well, drives the point home that much more forcefully. And he's quite right about that.

Some of the above might strike scientists as ridiculously simple, hardly worth the trouble of a post, while others might seem a bit too complex to be considered among the "basics." Nonetheless, I believe they're all concepts that even reasonably science-literate people tend to think they know more deeply than they really do. So a clear, careful explication of each of them, maintained in one handy spot at ScienceBlogs would help John/Jane Q. Public better navigate the trickier waters of advanced ideas that s/he encounters.

I'd like to close with a reality check.  Every scientific field has its own Top Ten list of fundamental concepts, so it's not just  grasping the physics outlined above, but also concepts in genomics, biology, chemistry, and every other discipline, which is one reason why the ScienceBlogs project is so badly needed. We live in the Information Age, and it's easy to get bogged down with Information Overload; so we're asking rather a lot of John/Jane Q. Public, the majority of whom don't seem to be learning the basics in their journey through our educational system.

I'm not condoning willfull ignorance, mind you, but we're up against a formidable challenge, and it's best to face the harsh reality head on. There is one hell of a communication gap between scientists and the general public, and we're not going to bridge it in one fell swoop, particularly when there is so much other information out there competing for their attention. The basic concepts series at ScienceBlogs is a terrific start, but the challenge of educating and reaching out to the public never ends.

99 luftballoons

It's been one of those weeks where I feel just like Robert Niro's anxiety-ridden mob boss in Analyze This. Granted, I'm just juggling my usual round of deadlines with book promotion; selling my DC condo; scouting around for a wedding venue; preparing for next week's lecture/martial arts demo in NYC; compiling year-end tax forms and receipts; and beginning to pack up the "nonessentials" in anticipation of my pending cross-country move. (I accidentally ordered the industrial-sized roll of bubble wrap, which now threatens to engulf my living room.) De Niro was dealing with panic attacks brought on by an upcoming "gangsta summit", the threat of a hostile (and potentially fatal) takeover, and the murder of a close friend whose death brought up long-repressed memories of witnessing his own father's murder. Complaining to Billy Crystal's long-suffering psychiatrist about the negative impact this was having on his emotional well-being, De Niro whimpers, "I got stress!"

My stress factors are more positive than that fictional gangster's myriad problems -- "Everyone should have your problems!" scoffs my pal Lee -- but then, I don't pop a few caps into innocent throw pillows to relieve the tension, either. Still, by yesterday afternoon, I was an extremely tightly wound ball of pent-up nervous energy. Yeah, baby, I got stress. So I took the night off, turned off the computer, and vegged out in front of the TV for a couple of hours before retiring early. Clifford at Asymptotia calls this "de-gaussing." What a great term -- I did feel like my body had all these trapped magnetic fields that had built up to very high levels over the course of the week. A few hours of mindless leisure and a good night's sleep successfully dispersed ("de-Gaussed") them.

Clearly I've been a bit preoccupied of late, which is why (a) I haven't been blogging that much, and (b) I missed the December 21 launch of NASA's Balloon-borne Large-Aperture Sub-millimeter Telescope, or BLAST. (Insert your own "BLAST off" joke here.) It's probably already landed by now. But I'm blogging about it anyway, because I love NASA's balloon-borne program. For all the high-tech rocketry that drives the space shuttle program, a lot of really fascinating science can be done using hot-air balloons, a technology that is more than 300 years old. For instance, for astrophysicists interested in collecting and analyzing X-ray and gamma ray emissions from celestial objects, much of that radiation is absorbed by the Earth's atmosphere, and thus never gets through to ground-based detectors. Mounting their equipment onto helium-filled balloons gets the instruments above that atmosphere, and the radiation they detect should help scientists get a better picture of star formation in distant galaxies, among other insights. It's much cheaper and faster than sending a manned starship out to the "mind-blogging edges of the universe to watch and study cosmic childbirth firsthand," as The Antarctic Sun so poetically phrased it.

Initially, ballooning had far less cosmic aspirations. In 18th century France, Joseph Montgolfier, the recalcitrant son of a successful papermaker noticed that laundry drying over the fire tended to form pockets in the fabric that billowed upwards. He didn't think much of it at the time (most accounts peg the year as 1777), because he was far too busy rebelling against familial expectations. Still, despite loathing formal education -- Wikipedia reports that he ran away from school twice -- he managed to cobble together a reasonably competent self-education in the physical sciences. While living in Avignon in 1782, he found himself in front of a warm, cozy fire, wondering if the same force that lifted the embers from the fire could be used to mount an air assault on, say, the fortress of Gibraltar, which had thus far proved unbreachable by land or sea.

Joseph built a boxy frame out of thin wood and covered the top and sides with lightweight taffeta, then crumpled up some paper underneath and lit it. As the paper burned, his homemade contraption lifted off its stand and hit the ceiling. He probably uttered the French equivalent of "Eureka!" And he promptly recruited his brother Etienne to develop the concept further: "Get in a supply of taffeta and of cordage, quickly, and you will see one of the most astonishing sights in the world!"

Joseph was a bit off base at developing an explanation for the effect: he believed the smoke from the fire contained a special "Montgolfier gas," and dubbed its buoyant property "levity." In reality, the hot air inside expanded, and thus weighed less, by volume, than the surrounding air. Okay, that's a bit overly simplistic. If you want to be more specific, it has to do with the properties of trapped gas, specifically, temperature, pressure and volume. The number of atoms inside the balloon doesn't change when it's heated (or cooled, for that matter). Rather, the gas expands and the balloon's volume increases so that its internal pressure remains in balance with the surrounding air pressure, and that volume shrinks as the gas cools -- again, to maintain the pressure balance. This is something that's familiar to anyone who's watched the deflation of mylar balloons when taken outside in cold weather, only to seem to blow back up again when it is brought safely back to a warm indoor environment. (Still craving details? Physics Central has more specifics right here.)

Back to the Montgolfier brothers: within a month they had built and successfully tested a much larger version of the contraption, and decided to conduct a public demonstration of their invention, which they did on June 4, 1783. A few months later, the brothers' "Aerostat Reveillon" demonstrated balloon flight once again before a huge crowd at Versailles that included King Louis XVI and Marie Antoinette. It also carried passengers: specifically, a duck, a sheep, and a rooster. (In fairness, I should note that a few aviation historians credit a Portuguese priest named Bartolomeu de Gusmao with the invention of the hot air balloon as early as 1709. But this is hotly disputed.)

As a result of these sorts of whizz-bang demonstrations (see? public demos work!), ballooning became all the rage in late 18th century France. In fact, in 1785, John Blanchard made the first aerial crossing of the English channel in a hot air balloon. By the mid-19th century, however, ballooning had given way to the dirigible (airship) craze, enormous envelopes shaped like a cigar and filled with hydrogen, a gas that is lighter than air at normal temperatures, thus dispensing with the need to heat the internal gas. (Of course, as the Hindenburg disaster aptly demonstrated in 1937, dirigibles had their own drawbacks.)

Today, there's all kinds of weather balloons deployed in the atmosphere, feeding back vital information on atmospheric pressure, temperature and humidity. Outfitted with a tracking device, they can even yield useful wind data. And last year, the National Center for Atmospheric Research (NCAR) launched a long-awaited weather observation platform called a driftsonde -- essentially a caravan of balloons carrying dropsonde weather instruments that drifts through the atmosphere collecting data, strewing its payload of dropsonde instruments along the way. NCAR has been testing prototypes since the 1970s, when scientists first developed instrument packages capable of surviving the harsh conditions in the stratosphere. But the end result was to bulky and heavy; thanks to three subsequent decades of exponential miniaturization in the electronics industry (and elsewhere), driftsondes are now a reality. Launched from an airport in Zinder, the second-largest city in Niger, on August 28, the very first driftsonde to be deployed wafted its way across the Atlantic, followed over the next month by seven other driftsondes.

It was probably just a matter of time before NASA realized the scientific potential of balloons as a cost-effective means of exploring space, including other planets. For instance, solar-heated balloons could be used instead of conventional parachutes to lower spacecraft to a planet's surface while conducting aerial photography. The Jet Propulsion Laboratory has an extensive research program in this area. In 2003, University of Chicago scientists launched an unmanned balloon into the stratosphere to search for high-energy cosmic rays, followed in 2004 by the balloon-borne Cosmic Ray Energetics And Mass (CREAM) collaborative experiment.

This isn't the first time BLAST has taken to the skies, either. Last year's launch out of Sweden was plagued by a broken mirror, quashing any hope of collecting extra-galactic data, although it did glean information but shiny celestial objects closer to home. The project's scientists hope to rectify that with this most recent flight.

BLAST's balloon is made out of ultra-thin polyethylene film, just like the plastic bags you get from the grocery store, just a little bit more durable, considering the balloon must withstand high-altitude conditions, not just groceries. Those conditions include something called "the polar vortex," apparently a type of atmospheric cyclone. The BLAST experiment ingeniously exploited that vortex, using it to carry its payload around the Antarctic continent before depositing back onto the Ross Ice Shelf, from where it was launched.

Equally impressive is the cutting-edge instrumentation. The "submillimeter" part of BLAST's acronym is  key, since it's the submillimeter wavelengths of radiation that will give us a bitter picture of distant galaxies, in part because it gets past the gas clouds that accompany star formation, which usually obscure regular optical observations. Even the plucky Hubble Space Telescope struggles with that. Plus, when a star forms, there's rather a lot of energy emitted in the submillimeter band, which means that much more data for scientists to analyze. But it's a bit tricky to detect radiation at that scale.

BLAST's reflective telescope uses an aluminum mirror, and it works like any other such telescope: light enters the front of the telescope and reflects off the primary mirror to a secondary mirror, which in turn directs the incoming photons into a receiver. However, BLAST must be pointed away from the sun and through the odd clear patches of the Milky Way galaxy. A "direct hit" of the sun's rays at those altitudes would literally fry the delicate instrumentation onboard. (On the upside, BLAST uses solar panels in the back to power itself.)

The receiver uses filters to divide the photons into three different wavelengths before they pass onto a detector array of highly sensitive heat sensors. "Heat," in this instance, is a somewhat relative term. The photons of interest to BLAST scientists are on the order of 30 degrees Kelvin. (The Antarctic Sun article compares this detection task to "sweeping your hand across a day-old campfire and trying to find a warm ember.)

So, we're talking about very low-energy light, and therefore the need for an even colder detector environment if the instruments have any hope of picking up those critical submillimeter signals. That's where the elaborate cryogenics system comes in. BLAST has its own self-contained refrigeration system capable of hitting lows your standard kitchen fridge can only dream about. Liquid nitrogen takes the first shift, chilling the instruments to 77 degrees Kelvin. Then liquid helium drops the temperature to 4 degrees Kelvin. By continuously pumping in more liquid helium, eventually the temperature cools to about three-tenths of a degree above Absolute Zero (0 degrees Kelvin). The end result of all this technological trickery should be reconstructed images on a par with what you'd get using Hubble, just at a lower resolution.

Even the futuristic notion of a space elevator might get a boost from balloons. (Guest blogger Lee Kottner covered that topic in depth here and here.) In September, LiftPort Group, based in Bremerton, Washington, conducted a 60-day field test of a cable held aloft by four helium balloons, considered a starting point for developing a space elevator. Apparently there were some issues with insects and bats, and we probably won't be seeing a space elevator any time soon, but the balloon-borne tether system could be used to secure WiFi platforms in rural areas, ensuring that every American can indulge their god-given right to check their Blackberries in the middle of nowhere. Balloons -- they're not just for 18th century French papermakers anymore.

let it snow

My last evening in Seattle, I was hanging out at a local Starbucks in Renton, a suburb just south of the city. So engrossed was I in my work, that I failed to notice it had begun to snow. In less than an hour, a good three inches had accumulated, and it didn't show any sign of stopping. Lacking snow tires on my rental car, I realized I'd never get back up the long steep hill leading to my folks' place (where I was staying), so I parked the car in a nearby corporate lot, and bummed a ride with a local guy named Joe who'd had the foresight to pack some chains in the back of his pickup. (Thanks again, Joe Whoever-You-Are; you spared me a mile walk in the snow.) It made the next morning a little stressful, given my noon flight back to DC. I had to dig out the car and gingerly navigate the by-then very icy side roads to the freeway -- which, mercifully, was dry as a bone. In fact, you'd never know people were stranded in the suburbs if you were driving on I-405, which might explain why Avis was so incredibly unsympathetic when I returned the car with only half a tank of gas, citing the inclement weather as an excuse.

Chalk it up to one of those weather flukes; it's been an unseasonably cold winter in Seattle, and the city does occasionally get a heavy snowstorm. But it snowed in Los Angeles this week! Los Angeles, people! As in, southern California, land of the orange groves, and my soon-to-be-hometown. (This year's crop went straight to orange concentrate, I'd wager.) Now that's an historic event! It reminded me of a scene in To Kill a Mockingbird, where  the little girl-narrator, Scout, sees pretty white snow flakes falling and assumes the world is ending. She's never seen snow before, since it's a very rare occurrence in rural Georgia Alabama. The world didn't end then, and it's not ending now, but it's just one more bit of evidence that weather is a very wacky thing.

Unless, like Scout, we've never experienced a genuine snowfall, we probably take snow a bit for granted. It's just another form of precipitation, after all, and we have a pretty solid grasp of that particular cycle. Just for the record, snow is not frozen raindrops; that would be sleet. Under certain conditions, water vapor can condense directly into tiny ice crystals, skipping the raindrop phase altogether, and usually forming the shape of a hexagonal prism (two hexagonal "basal" faces and six rectangular "prism" faces). But that crystal also attracts more cooled water drops in the air. Branchings sprout out from the single crystals' corners to form snowflakes of increasingly complex shapes. And yes, for all intents and purposes, no two snowflakes are shaped exactly alike, at least according to Caltech physicist Kenneth Libbrecht, who runs this Website devoted entirely to snow crystals. But there are 35 different types of snow crystals, all of which he has carefully documented.

Libbrecht must have been thrilled to see snow in Los Angeles, since he usually has to create his own ice crystals in the lab, or go to more frigid climes, like Michigan or Alaska or Ontario, to make his high-resolution microscope images of snowflakes. (You can see movies of lab-based snow crystals forming here.) Even then it's a tricky business. He has to use a small paintbrush to transfer the delicate structures to a glass slide, taking the picture with a digital camera mounted on a high-resolution microscope. All of this is done outside to keep the crystals from melting too quickly. The final images are quite striking -- so much so that last October, they were featured on a new 39-cent commemorative postage stamp, courtesy of the US Postal Service.

Not surprisingly, the shapes of snowflakes and snow crystals have long fascinated scientists, like Johannes Kepler, who took some time away from his star-gazing in 1611 to publish a short paper entitled "On the Six-Cornered Snowflake." He was intrigued by the fact that snow crystals always seem to exhibit a six-fold symmetry. Some 20 years later, Rene Descartes waxed poetical after observing much rarer 12-sided snowflakes, "so perfectly formed in hexagons and of which the six sides were so straight, and the six angles so equal, that it is impossible for men to make anything so exact." He pondered how such a perfectly symmetrical shape might have been created, and eventually arrived at a reasonably accurate description of the water cycle, adding that "they were obliged to arrange themselves in such a way that each was surrounded by six others in the same plane, following the ordinary order of nature." (The lack of a detailed explanation can be excused: it took the development of x-ray crystallography for scientists to really be able to study the shape and structure of snow crystals/flakes in any great detail.)

Libbrecht has an historical predecessor in Robert Hooke. Hooke's Micrographia, published in 1665, contained a few sketches of snowflakes he observed under his microscope -- sketched rapidly, one assumes, since the flakes no doubt melted soon after being placed under the lens, even working outdoors. If only he'd had access to Libbrecht's equipment, he wouldn't have had to do everything by hand -- and he would have appreciated the far more intricate details observable under orders-of-magnitude increases in resolution.

But nobody performed a truly systematic study of snow crystals until the 1950s, when a Japanese nuclear physicist named Ukichiro Nakaya identified and cataloged all the major types of snow crystals. (Nakaya had the bad luck to be appointed to a professorship in Hokkaido, with no available facilities for his nuclear research, so he applied his considerable skills to what was readily available: snow crystals. Now that's taking lemons and making lemonade.) He also proved Descartes wrong in the Frenchman's assertion that no man could make anything so perfect. Nakaya was the first person to grow artificial snow crystals in the laboratory. In 1954 he published a book on his findings: Snow Crystals: Natural and Artificial. Here's what Libbrecht's Website has to say about it: "Nakaya's book offers a superb look at a scientific investigation which begins with almost nothing, and proceeds through systematic observation toward an accurate description of a fascinating natural phenomenon."

Thanks to Nakaya's pioneering work, we now know that certain atmospheric conditions, like temperature and humidity, can influence a snowflake's shape. For instance, those shapes tend to be simpler in low humidity. The higher the humidity, the more complex the shape, and if the humidity is especially high, they can even form into long needles or large thin plates. Scientists aren't entirely sure why, but they suspect it has to do with the complex underlying physics of how water vapor molecules are slowly incorporated into the growing ice crystal -- what Descartes termed the "ordinary order of Nature." There's still a lot of mystery in that ordinariness.

That's why NASA has launched the Global Snowflake Network, a massive project that aims to involve the general public to  "collect and classify" falling snowflakes. The data will be compiled into a massive database, along with satellite images, that will help climatologists and others who study climate-related phenomena gain a better understanding of wintry meteorology as they track various snowstorms around the globe. Participating students, teachers, and other interested parties will have the chance to take part in real science, and learn more about how climate, temperature and other atmospheric features combine to produce weather phenomena.

So next time snow falls in your area this winter, take a few moments from building snowmen and lobbing snowy missiles at the annoying kid down the street, and look more closely at each individual flake. You might even consider signing up with the GSN, thereby recording your observations for scientific posterity.

seattle sightings

I'm back from Seattle, where I didn't get the chance to take in nearly as many of the fantastic papers at the American Astronomical Society (AAS) as I would have liked. Most of the major results have been covered elsewhere in the blogosphere anyway. But I did find time to squeeze in one last press conference: a sort of catch-all session on unique approaches to education and outreach.

For instance, those controversial new NBA basketballs have been in the news over the last few months, so it was particularly timely to have John Fontanella on hand to talk about the four basic physical forces that affect the flight of a basketball: gravity, buoyancy, the drag force, and the Magnus force. Fontanella is a physics professor at the US Naval Academy and author of a new book, The Physics of Basketball (Johns Hopkins University Press). Fontanella has first-hand knowledge of the sport: he was a college basketball star at Westminster College, even setting a school record when he scored 51 points in a single game in 1966.

His basic "hoopothesis" is that the best shooters try to minimize the speed of the basketball just as it reaches the basket. Fontanella filmed several shooting sessions and analyzed the footage, determining such factors as initial position, velocity and launch angle. From that data, he experimented with several computer models. He found that, given just the effects of gravity and the initial conditions, the ball overshoots. So he added in some air resistance: the ball over-corrects. So then he added in lift via a rotational backspin on the ball when it's launched, and found that came pretty close to predicting the perfect trajectory for the basketball to travel.

Fontanella likes to cite his model as an example of how physics can be used to model real-world phenomena. For instance, Shaquille O'Neal -- notorious for not being very good at taking foul shots -- would probably find Fontanella's "hoopothesis" interesting, since it states he should shoot his foul shots at a launch angle of 48.7 degrees. ("Obviously he doesn't do that," cracked Fontanella.) And as it happens, physicists at the University of Texas, Arlington, were able to demonstrate that the new NBA ball had some critical flaws, which may have influenced the NBA's decision to return to the old regulation basketball.

I also heard about a fascinating acoustical effect that occurs with mugs of hot chocolate, ably demonstrated by Bradley Carroll of Weber State University with a packet of Swiss Miss instant cocoa. Tapping a spoon against the bottom of a mug of freshly made hot cocoa produces a tone of constantly rising pitch.  If you stir the cocoa some more, the pitch will plunge before it starts rising again. And it's a significant increase: about three octaves, "an eightfold increase in frequency, twice the rise in pitch you encounter while singing the 'Star Spangled Banner,'" says Weber. Yet there is no noticeable change in the actual mug of cocoa.

He demonstrates the effect to pique his students' interest and assigns them the task of "solving" the mystery by performing a series of experiments. They test for the effect by changing the variables, using hot water, cold water, milk, cocoa, tea, instant coffee, instant cider Kool-Aid, sugar, salt and even dishwashing liquid, in an attempt to narrow down a possible hypothesis to explain the effect. The students get to satisfy their curiosity and gain first-hand experience with the scientific method -- not the severely distilled version of that method routinely described in textbooks, but how scientists work in real life. "A good mystery is far more compelling than mere 'fact,'" according to Weber, who prefers P.W. Bridgman's description of the scientific method: "The scientific method is doing your damnedest, no holds barred."

Weber likes to hoard the "secret" behind the hot chocolate effect a little, so I hope he doesn't mind that I reveal it here. The best explanation he's been able to find is in a May 1982 paper by Frank Crawford published in the American Journal of Physics. The effect is similar to how a sound is produced when one blows air across the top of a partially filled Coke bottle. It's the vibrating air above the Coke's surface that gives rise to a sound wave, and the tone's pitch depends on how full the bottle is: the more liquid, the less air, and the higher the pitch. But with the hot cocoa, it's the liquid below the surface that vibrates, and produces a sound wave. Crawford argued that stirring the instant cocoa creates tiny bubbles that lower the speed of sound in the liquid. Since it takes longer for the sound to travel through the cocoa, the pitch falls. Over time, the bubbles rise to the surface and burst, enabling the sound to travel faster. So the pitch rises.  Of course, eventually the effect dies out, so Weber thinks there might be more to the story than just the bubbles that get stirred up when the cocoa is first made. Perhaps one of his students will come up with a more thorough explanation someday.

The other interesting paper involved a strange acoustical effect on a more cosmic scale. NASA's Chandra X-Ray Observatory has detected a "light echo" from the supermassive black hole located at the center of our Milky Way galaxy. It's evidence of a powerful outburst of X-ray radiation from the black hole, generated by gas falling into it. The primary burst would have reached Earth some 50 years ago, before satellites were in space to detect it, but the "echo" consists of reflected radiation from the gas clouds near the black hole. It took longer to travel through space, and by the time it arrived, Chandra was on hand to record it. (Sometimes it really does come down to having the right equipment in the right place at the right time.) The astronomers who detected the echo think it indicates that the black hole consumed a very large mass roughly the size of the planet Mercury.

Finally, here's a few random tidbits for the gossip pages: I met Rob Knop of Galactic Interactions, who wins major points for coming to my talk at Elliott Bay Bookstore -- unfortunately held on the same night as a Seahawks playoff game, so we needed as many extra bodies as we could get -- and for buying several copies of my books. Also, he's very funny and an excellent dinner conversationalist. Next time I hope he brings his unicycle. Steinn, however, proved more elusive, perhaps because he was so busy covering the actual meeting, along with Rob, that he was never hanging out in the press room.

I also dragged my 14-year-old niece to a Skeptics Society dinner Sunday night, where we briefly met Phil Plait, who was slated to give a talk on the Moon Hoax. He seemed pale and subdued. Within 14 minutes he was going green, excused himself, and ended up cancelling his talk and heading back to his hotel room. Rumor has it he spent an uncomfortable night having "conversations with the porcelain Buddha." I never saw him again, but he's been blogging, so I assume he survived. Perhaps it was the crushing disappointment at finding that I look nothing like my faux-Frech avatar, Jen-Luc Piquant. Or perhaps this is just the effect I have on fellow bloggers. I mean, I met Michael Berube over the Christmas break, and next thing you know, he's retiring his blog. Let's hope Bad Astronomy weathers the "Jen-Luc Curse" and continues its long, fruitful life in the Blogosphere.

from pole to pole... to pole?

There's been quite a bit of buzz in the blogosphere about Sunday's exciting news: a 3D image "mapping" the dark matter. (Links to some excellent explanations with even more links can be found here, here, here, and here.) Sadly, I missed the press conference on the subject due to prior commitments, but I did finally make it down to the Washington Convention Center today to take in a few presentations at the American Astronomical Society meeting. In addition to the enormous stack of press releases awaiting my perusal, I received a spiffy Press badge that attaches via a magnetic strip. So much better than the usual safety pin variety (which can ruin a fine silk blouse), or those awkward shoe-lace type things one hangs around one's neck -- definitely not designed for a woman's anatomy, shall we say.

Chalk up yet another innovative application of the humble magnet: meeting badges. What will they think of next? If "they" means astronomers and researchers working at the Arecibo Observatory in Puerto Rico, they've thought of something far more ingenious to account for some unusual observations in the radio emission signatures produced by a pulsar in the famous Crab Nebula, located in the constellation Taurus some 6300 light years away. Here's the sound bite version of the story, with more details further down:

The researchers expected the radio emission spectra to be identical for both the main pulse and the interpulse, since each is associated with a magnetic pole (north and south). Prior theoretical models of pulsars predicted this would be the case, but the experimental data showed otherwise. The two signatures were wildly different, and among the possible explanations is the existence of a third "magnetic pole" located elsewhere in the star. It's a classic case of the left hand not knowing what the right hand is doing -- just substitute "north pole" and "south pole" for right and left. And according to theorist Jean Eilek of New Mexico Tech, "It knocks  just about every existing theory of pulsar radio emission for a loop." This makes the Crab Nebula (henceforth dubbed "Crabby") very special indeed, since other pulsars fall pretty much in line with existing theoretical models.

The story of the Crab Nebula goes back 1000 years. Or, if you want to be more poetical about it: A long time ago, in a galaxy far, far away, a massive star died a violent, explosive death, and then collapsed into a spinning neutron star. In 1054 AD, the light from that supernova explosion (Supernova 1054) finally reached Earth, shining brightly enough to be seen in daylight for 23 days, and remaining visible in the night sky for a whopping 653 days. It was such a rare event that there is mention of it in the records kept by Japanese, Arab, and Chinese astronomers, as well as circumstantial evidence indicating that the Anasazi also observed the supernova. The Crab Nebula is the cloudy remnant from that spectacular death -- a gassy sort of memorial to a once-magnificent star.

Thus was Crabby born. It took awhile for him to show his face to astronomers, however. Fast forward some 700 years to 1731, when an English physician and amateur astronomer named John Bevis recorded his observation of  Crabby's pretty blue glow, which derives from the whirling electrons whirling at the speed of light around the star's magnetic field lines. He included it is his own star atlas, Uranographia Britannica, which was published posthumously in 1786, even though he completed it in 1750. (The publisher went bankrupt. Bummer.) Twenty-seven years later, Charles Messier would independently "rediscover" the Crab Nebula.)

But there was more to Crabby than simply met the eye: he turned out to have a pulsar as a "heart." Fast forward another 250 years or so, and a young female graduate student working at the Mullard Radio Astronomy Observatory near Cambridge. In the summer of 1967, Jocelyn Bell was manning the new telescope she'd helped her advisor, Anthony Hewish, cobble together, and analyzing the resulting data (some 100 feet of paper every day). She soon noticed an anomaly in the data: a "bit of scruff" that turned out to be a regular signal, consistently coming from the same patch of sky. Could it be the long-awaited signal from an extraterrestrial civilization? Bell and Hewish mischievously dubbed the source "LGM-1" for "Little Green Men," although it turned out to be a pulsar -- an exciting discovery that earned Hewish a Nobel Prize. Bell was famously overlooked for the honor, even though she was the one who technically "discovered" the original anomaly in the data.

In essence, a pulsar is a rotating neutron star.  Just like a lighthouse, it emits twin beams of radiation that appear to pulse 30 times per second, producing a main pulse and an interpulse. That rotational energy is converted into electromagnetic energy, giving rise to the short, powerful burst of radio emissions observed by astronomers. However, no one is quite sure what the actual physical mechanism is that causes the energy conversion in the first place, hence, the continued interest of astronomers in studying these funny little objects. The current thinking is that it results from a collapsing soliton, and that collapse abruptly converts energy into electromagnetic radiation. What causes the collapse is still a bit of a mystery.

Pulsars generate simply enormous magnetic and electric fields, thanks to plasma clouds (patches of electron/positron gas) in its atmosphere, from whence the emission blasts emerge. Eilek's colleague, Tim Hankins, estimates the plasma clouds to be smaller than a soccer ball and slightly larger than baseball, and the blasts of radiation -- which can be as powerful as 10% the total power of the sun -- occur over very short time frames: on the order of four-tenths of a nanosecond. In the most recent work, Hankins and his colleagues took the average profiles of Crabby's main pulses and interpulses, across a wide range in the electromagnetic spectrum (radio to infrared all the way up to X-ray emissions). Instead of the two being identical, the main pulse shows no sign of the strange frequency structure in the main pulses, while those very short powerful blasts never show up in the interpulse signature. Even more unusual is that the band "spacings" found in the interpulse spectrum aren't equal, but seem to change in proportion to the frequency.

That's just plain weird, according to Hankins, because it completely rules out the previously predicted train of equally spaced bursts of power in time. Even Eilek admits to being "totally perplexed" by the unexpected results. She's now mulling the possibility of attributing the unusual behavior to a kind of resonant cyclotron emission, similar to the "zebra bands" observed in the spectra of solar flares. Hankins isn't entirely satisfied with that alternative, and has proposed his own explanation: we're seeing interference fringes. That interference might be coming from a heretofore unsuspected third magnetic pole that is disturbing the magnetic fields normally generated by north and south poles. I guess we could call it the "east pole." That third pole might even have a partner, bringing the total to four. (As I.I. Rabi said when the muon was first observed, "Who ordered that?!?")

It's clear from these results that, as far as Crabby's pulsar is concerned, the old bipole model just doesn't cut it. Adapting existing models to incorporate additional poles is, to put it mildly, quite the challenge. Many of us performed the basic magnetic field experiment using iron filings on a white piece of paper; it enables you to "see" the magnetic field lines generated by the north and south poles of the magnet in the pretty patterns the filings make. Add two more poles, however, and the picture becomes much more complicated -- so complicated that it becomes impossible to accurately predict or map the magnetic field structure.

This, my friends, is real science in action. Scientists encounter an unexpected experimental result that doesn't match the theoretical models that have worked perfectly well to date. Rather than going into denial and clinging to the past, like whacked out Young Earth Creationists, they embrace the unknown, and start casting about for alternative models that might account for the new data.

They might not get the chance to solve the mystery if federal funding woes continue. Last November the National Science Foundation made public a report recommending decreased funding for the Arecibo Observatory. Unless other sources of funding are found, the facility will be shut down in 2011, while the radio astronomy program could be canceled as soon as this September. That would be a sad fate for a highly recognizable facility: it was used as a filming location for the 007 classic, Goldeneye, in at least one episode of The X-Files ("Little Green Men"), in the film Contact, and in the opening scenes of Species.

And it's not the only facility in trouble, as this article in The New York Times makes clear. After narrowly averting disaster last year, Brookhaven National Laboratory is once again facing closure because of funding red tape in Congress. See Gordon Watts' take here, and a copy of the letter circulated by Fermmilab's director, here. The situation is so dire that the American Physical Society has issued a call to action for its members to write their Congressional representatives urging a reversal of the funding declines. Check it out, and write your own Congressman to help save the future of science. Otherwise we might one day no longer be able to take beautiful pictures like this one, featuring Crabby in all his glowing blue glory:

on butterfly's wings

One of the best-known poems by Gerard Manley Hopkins -- a Victorian-era minister whose writings frequently centered on the glories he observed around him in nature -- opens with a tribute to the phenomenon of iridescence: the wings of kingfishers and dragonflies, in Hopkins' poem, but it can also be found in the wings of cicadas, and butterflies, in certain species of beetle, and in the brightly colored feathers of male peacocks. A firm believer in divine hierarchy, Hopkins found a metaphor for man's relation to God in this peculiar attribute of nature: "Each mortal thing does one thing and the same/... Crying 'What I do is me, for that I came.'"

I don't share Hopkins' religious ecstasy, but I have always appreciated his skillful use of language and meter, and his unabashed appreciation for the natural world. Nature fits form to function, and everything has its place in the delicately balanced ecosystem. You don't need to believe in God to marvel at that, or at the many examples of iridescence in the world around us. Equally marvelous is the unusual cause of those bright flashes of hue. The color we see doesn't come from actual pigment molecules, but from the precise lattice-like structure of the wings (or shells, or feathers), which forces light waves passing through to interfere with itself, so it can propagate only in certain directions and at certain frequencies. And the brilliant colors that result change depending on one's point of view. In essence, they act like naturally occurring diffraction gratings.

Physicists call these structures photonic crystals, an example of "photonic band gap materials", meaning they block out certain frequencies of light and let through others. (If you prefer an explication of the science from America's beleaguered pop princess, Jen-Luc Piquant suggests you check out Britney Spears' Guide to Semiconductor Physics. Now that Britney has lost the baby weight and the loser husband, Jen-Luc fervently hopes she will return to her cutting-edge physics research.) This makes them "tunable", particularly the manmade varieties, because of those highly ordered arrays of periodic "holes". Anything tunable is by definition controllable, and therefore useful for practical applications. Photonic crystals are used most often as waveguides for light in telecommunications/fiber optics systems, or other places where scientists want to be able to control either the frequency or the direction of light.

Over the last six months, there's been several interesting new developments in the effort to exploit the features of naturally-occurring photonic crystals in innovative ways. (I've been collecting newsy items on the topic for several months now, in hopes of finally finding time to write a blog post about it. That time has come.) Most recently, in November, Chinese researchers (Jin Zhang and Zhongfan Liu) at Peking University announced that they have figured out a way to use the wings of cicadas as stamps to pattern polymer films at nanometer size scales -- a feat that is quite challenging using conventional microfabrication technology. The wings are rigid enough so that when they are pushed down onto a smooth polymer film, that film is imprinted with a negative version of the array pattern.

The wings are also chemically stable, plus they have a waxy coating which results in very low levels of surface tension. This is important, because the wings don't end up getting stuck to the polymer film after imprinting. They can be removed while leaving the stamped pattern intact. That pattern is then transferred to silicon via a more traditional etching process, thereby forming "nanowells" on a silicon chip. Such chips "show promising anti-reflective properties," according to Zhang and Liu, and could be useful for optical imaging, or in the use of Raman spectroscopy for detecting molecules. Liu phrased it best: "There is a lot that nature can teach us about nanotechnology."

Butterfly wings get their color from naturally occurring photonic crystal structures in scales made of chitin, a polysaccharide that shows up in all kinds of insects. Those scales are arranged like tiles on a roof, except they measure a mere tens of micrometers across. Last September, New Scientist reported that a group of researchers have measured the structure and optical characteristics of the photonic crystals in butterfly wings for the very first time. They did it by studying electron microscope images of the scales. It turns out that each side of the wing contains different photonic structures: a metallic blue produced by single crystals, and a dull-ish green that results from a more random arrangement of crystals. Precisely ordering the lattice structure is critical to achieving the most brilliant colorful effects -- and to controlling the propagation of light at the desired frequencies. Which is why telecommunications applications rely on manmade photonic crystals rather than nature's more random arrangements.

Still, butterfly wing crystals can produce green, yellow and blue colors, depending on their overall effect, and the researchers managed to generate red reflections as well. That's significant because such a palette could be used in flat panel displays, simply by mounting an array of crystals only tiny MEMS arms to change their orientation. So any given "pixel" could produce red, green or blue. A September 1, 2006 paper in Optics Letters by a team of Swiss scientists described a similar approach using diffraction gratings and piezoelectric polymers (which contract whenever an electric voltage is applied) to faithfully reproduce a fuller range of colors than can currently be achieved in conventional displays, whether they be standard TVs, LCDs, or plasma screens. (For instance, they can't reproduce the blues observable in the sky or in the sea.) Manuel Aschwanden of the Swiss Federal Institute of Technology in Zurich headed the project, and described the grating as having one side molded into something that looks for all the world like microscopic pleated window shades.

More frivolously, copying the structure of butterfly wings is giving rise to spiffy new kinds of make-up, giving a whole new meaning to the term "butterfly effect." For instance, L'Oreal offers eye shadow, lipstick and nail polish featuring these iridescent effects, bringing nature's beauty to the cosmetics counter. This is achieved by stacking nanoscale layers of materials like mica, silica or liquid crystals, of varying thickness to give each material a specific refractive index. For instance, a stack 80 nanometers high produces blue, while one 120 nanometers high produces red. In the package, though, the stuff just looks white; the colors appear when the makeup is applied and exposed to light. There are the usual concerns about using nanoparticles in cosmetics, when little is known to date about potential health risks, but that hasn't dampened the enthusiasm for such novelties. Yet.

Researchers at the University of Toronto have developed a new elastic type of photonic crystal that changes color with the application of pressure. It also mimics the structure of butterfly wings and opal (the gemstone is another common example of a naturally occurring photonic crystal): it resembles a 3D honeycomb. They hope to develop the material further in hopes of using it to, for example, capture full-color fingerprints. The obvious advantage is the enhanced contrast and sensitivity to detail, making it easier to analyze prints for identification purposes. But any impression picked up by the elastic photonic crystal is visible immediately in bright hues, with no need to first convert that raw data into electrical signals for computer analysis. The Toronto material could also be used as pressure sensors in consumer electronics or airbag deployment -- or just for children's toys.

Imagine a toddler being able to squeeze a toy and watch the color change right in front of his/her eyes! Imagine the wonder the child would feel, especially when s/he was old enough to realize that it wasn't magic, but a one that arises from Nature itself, that man has seen fit to copy and put to good use. I think even Hopkins would be suitably impressed at what the scientific study of a simple butterfly's wing has wrought. So it seems fitting to close by quoting another Hopkins' poems, "God's Grandeur." It presents a vivid image of the Holy Ghost brooding over our imperfect world "with warm breast and with ah! bright wings."

break out the bubbly

"Come quickly, brothers, I am drinking stars!"
    -- Dom Perignon, 17th century monk

Popular legend has it that the 17th century monk Dom Perignon invented champagne -- hence the classic brand that bears his name. That's not entirely correct. The monk was indeed cellar master at the Abbey of Hautvillers, charged with getting rid of the bubbles in the bottled wine because the bottles occasionally exploded from the internal pressure. This being 17th century France, the explosions were considered to be the devil's handiwork. Because only Satan would be so unequivocally evil as to ruin a batch of perfectly good wine. French monks weren't big on the teetolling. The truth is, nobody is entirely sure who invented champagne. The first mention of a commercial sparkling wine pops up around 1535 in Languedoc. From there, it gradually spread around the world.

Dom Perignon did come up with lots of improvements to making the bubbly beverage. The basic process is fairly simple. Champagne grapes are generally picked earlier, when the fruit's sugar levels are lower, with higher acid levels. Like every wine, the grapes are pressed and sealed in containers to ferment, converting the natural sugars into alcohol. In this stage, the carbon dioxide byproduct is allowed to escape. The result is a base wine from which winemakers produce a tasty blend. To turn it into champagne, there must be a second fermentation, and this time the carbon dioxide trapped in the bottle, and stays dissolved in the wine.

For this part of the process, the blended wine is poured into sturdy bottles with yeast and a small amount of sugar (a concoction known as the liqueur de tirage). How much pressure is in the bottle depends on how much sugar is added during the second fermentation. For those who care about such details, 6 bars (or atmospheres) of pressure inside the bottle is the standard value, and this requires 18 grams of sugar.  The European Commission regulates the amount of yeast: 0.3 grams per bottle. Controlling the carbonation level can be tough; for every bottle of perfectly effervescent champagne, there are bottles that fail to be sparkly at all, and those that explode from the build-up of too much pressure. Hence the need for precise amounts -- even to the point of official regulations.

Champagne adheres to "Henry's law" (sorry, couldn't find out much about who this "Henry" fellow was -- but perhaps a commenter can help). The amount of gas dissolved in a fluid is proportional to the pressure of the gas with which it is in equilibrium. And that's what makes champagne bubble, gives it "effervescence" -- which in turn gives rise to the tingly sensation on one's tongue that Dom Perignon likened to "drinking stars." When the bottle is still corked, the carbon dioxide gas dissolved in the wine is in equilibrium with gas trapped in the space between the cork and the liquid. When you uncork the bottle and release that trapped gas -- no more equilibrium. So the carbon dioxide is emitted from the wine through bubbles to re-establish that equilibrium.

As much as we've learned about perfecting the manufacturing process, champagne still retains some of its mysteries -- for the time being. Over the last five years or so, scientists have gleaned several new insights into the dynamics of champagne bubbles, and leading the pack is an associate professor of physical sciences at the University of Reims Champagne-Ardenne named Gerard Liger-Belair, author of Uncorked: The Science of Champagne, and a consultant for Moet and Chandon. Jen-Luc Piquant considers him the Champagne King, a much more elegant moniker than, say, "Dr. Bubbles." (One should not confuse Liger-Belair -- a serious scientist -- with "Champagne Charlie," a 19th century famous entertainer named George Leybourne, who may have made the first celebrity endorsements -- on behalf of Moet. The drink soon became associated in the public mind with Leybourne's highly sophisticated image.)

Ask any champagne connoisseur and s/he will tell you that the mark of a fine bottle of the bubbly depends on the size of the bubbles. Less is more: the smaller the bubbles, the better the champagne. LaPlace's Law states that the smaller the bubble, the higher the pressure. Fine bottled champagne has an internal pressure of about 6 atmospheres, so the resulting bubbles would measure around 0.4 microns (microns, people!) in diameter. Why should this have an impact on flavor? According to Liger-Belair, if the bubbles are smaller, there are more of them to release flavor and aroma.

Unfortunately, champagne makers have yet to figure out how to control bubble size, which is why scientists like Liger-Belair are avidly researching the physics of effervescence. He believes that a greater understanding of the various chemicals dispersed in the wine could hold keys to controlling bubble formation. A couple of years ago, he showed that even though champagne and more low-brow sparkling wines have bubbles of different sizes, they nonetheless have identical diffusion co-efficients, which lends credence to his theory. Liger-Belair wrote a recent article for Europhysics News about his latest work in this area. (For a more general article on the physics of fizz by Peter Weiss, go here.) And his work has implications beyond the bubbly: bubble formation resulting from gases dissolved in a liquid is one of the sticky points of fluid dynamics, so a better understanding of the underlying physics could yield insight into the nitrogen bubbles that form in the blood vessels of surfacing divers, causing "the bends," or in extreme cases, death.

How/why do the bubbles form in the first place? Scientists used to think that minuscule rough spots on the surface of the glass trapped pockets of air, forming bubbles. Liger-Belair found otherwise. There are impurities stuck to the glass wall, in the form of hollow cellulose fibers shaped like cylinders, and these serve as "bubble nurseries." When the champagne is poured into the glass, the liquid can't penetrate to the inside of the follow fiber, forming bubbles, because the carbon dioxide molecules have a high enough pressure to force their way into the fibers. Once they get big enough, they break free and rise to the surface, but there is still a carbon-dioxide-rich bubble trapped in the hollow fiber, so the bubbles keep generating. Liger-Belair says that these bubble nurseries can produce 30 bubbles per second, compared to 10 bubbles per second in beer, which has much less carbon dioxide content.

Champagne has become the mainstay of New Year's Eve celebrations but most of us become quite bewildered when faced with the task of choosing a good bottle. Do we stick with our friendly 17th century monk, Dom Perignon? Indulge in the fictional Lord Peter Wimsey's favored Veuve Cliquot? Or honor the spirit of "Champagne Charlie" by imbibing some Moet and Chandon?  For those (like me) who could use some help, we highly recommend a delightful blog called The Naked Vine -- a guide to affordable good wines written by a guy in Kentucky named Mike. Mike has saved us from completely humiliating ourselves in wine stores on more than one occasion. And his most recent entry is a guide to good champagnes.

I celebrated the New Year with dinner at Lebanese Taverna with Future Spouse and Mondo Bob, toasting the changeover to 2007 with a rather young but tasty zinfandel; its fruitiness blended nicely with the spicier Lebanese fare. Kudos to Future Spouse for the selection. So I was the picture of holiday respectability (yawn -- bored now). Jen-Luc Piquant, however, frolicked in Cyberspace into the wee hours, and indulged in quite a bit of Internet bubbly, judging by her the extent of her virtual hangover this morning.

Maybe it's the hangover talking, but Jen-Luc insists she impressed her fellow avatars by demonstrating her favorite bottle-opening technique: sabrage. The fact that the term shares a root with "sabre" isn't coincidence; the technique became hugely popular during the days of Napoleon's empire building, when every red-blooded male was swaggering around with a handy sabre at his side, ready to make quick work of any menacing champagne bottles in the vicinity.

One who uses sabrage slides the sabre along the body of the bottle toward toward the neck; it's not for slicing purposes, however. Rather, the force of the blade hitting the lip separates it from the neck of the bottle, and cork and lip fly away together in a pretty trajectory that could probably be easily calculated using Newton's laws. There's a handy real-world physics problem to assign students in the classroom; I guarantee 100% attendance the day of the in-class demonstration. Weaponry and the prospect of potential blood-spillage never fails to draw a crowd.

There are other hazards associated with champagne that have nothing to do with its alcoholic content. Here's a random bit of historical champagne trivia: there are tunnels under the Thames River in London, and the earliest of these was built using airlocks to maintain massive pressures inside the tunnel to keep the water from flooding in during construction. The day the two shafts from either side of the river met in the middle, local politicians gathered in the tunnel to celebrate with a dinner. I couldn't find any record of the quality of the food -- I'm just impressed they found a caterer willing to venture into a tunnel under the Thames -- but the champagne, alas, was disappointingly flat. That's because the high pressure in the tunnel kept the dissolved carbon dioxide from escaping into the air as bubbles -- there was no need to re-establish equilibrium. The politicos drank it anyway, because wine should never go to waste. Unfortunately, when they left the confines of the tunnel, the ambient pressure dropped rapidly, and "the wine popped in their stomachs, distended their vests, all but frothed from their ears." Apart from intense gastric pain, the politicians were ultimately unharmed.

We also learned yesterday -- courtesy of the molecular gastronomy blog Khymos -- that a Swedish physicist named Hans-Uno Bengtsson has precisely calculated how far you can shoot a champagne cork (using the more traditional uncorking method). He's even written a book about it with a sommelier named Mischa Billing. According to Bengtsson, the initial cork velocity would be about 20 meters per second, or 70 kilometers per hour. If you ignore air resistance (as physics teachers almost always do for simplicity's sake), the cork should travel some 40 meters. The folks at Khymos have a whole bunch more fascinating fun facts about champagne which you can check out here.

Or you can just sit back and enjoy the first day of 2007 with no pressure to achieve much of anything.  Perhaps even pop open a leftover bottle of champagne, if you're feeling especially indulgent. It goes nicely with standard brunch fare. And oh yes -- Happy New Year, everyone!