Cocktail Party Physics

ticket to ride

One of my new favorite GeekGrrl blogs is The Mary Sue -- a tantalizing mix of popular culture, technology, fashion, offbeat humor and weird science. What's not to love? This week they stumbled across a fascinating project undertaken by the fine folks at Design Interactions Research, an organization that "focuses on exploring interactions between people, science and technology on many different levels." This particular "interaction" is the brainchild of Julijonas Urbonas, a designer, artist, engineer and PhD student specializing in the "gravitational aesthetics" as played out in "gravitational theater." He is also managing director of a Lithuanian amusement part, so it's only natural that his project is called the Euthenasia Coaster. As he describes it:

“Euthanasia Coaster” is a hypothetical euthanasia machine in the form of a roller coaster engineered to humanely – with elegance and euphoria – take the life of a human being. Riding the coaster’s track, the rider is subjected to a series of intensive motion elements that induce various unique experiences: from euphoria to thrill, and from tunnel vision to loss of consciousness, and, eventually, death. Thanks to the marriage of the advanced cross-disciplinary research in aeronautics/space medicine, mechanical engineering, material technologies and, of course, gravity, the fatal journey is made pleasing, elegant and meaningful. Celebrating the limits of the human body, this ‘kinetic sculpture’ is in fact the ultimate roller coaster: John Allen,former president of the famed Philadelphia Toboggan Company, once said that “the ultimate roller coaster is built when you send out twenty-four people and they all come back dead. This could be done, you know."

That's right: A Killer Coaster! And if you're wondering whether an amusement park ride could really be all that lethal -- yes, it can, depending on the coaster's design, and Urbanos has deliberately designed his coaster to maximize the kinds of adverse physical effects other coaster designers seek to minimize. (Discovery has a terrific Website where you can try your hand at designing your own coaster.)

It's not just about speed; you need a smooth ride. Early roller coasters moved very slowly compared to modern scream machines, but even at slow speeds, a simple loop-the-loop can cause whiplash and other neck and back injuries. In 1885, the Flip-Flap debuted with a 25-foot diameter loop-the-loop, but it closed in 1903 because of all the injuries suffered by passengers because of the sharp, jerking motions. There's a reason modern looping coaster designs incorporate a teardrop shape; it minimizes the forces that cause such havoc with the human body.

Speed can certainly be a factor, as in the infamous encounter in 1999 between male model Fabio and a wild goose. Busch Gardens in Williamsburg, Virginia, brought in Fabio for the opening of the park’s new roller coaster, Apollo’s Chariot -- he of the flowing blond locks, chiseled jaw and impeccably sculpted torso, best known for posing in strategically ripped shirts on the covers of mass-market romance novels, and for hawking butter substitutes on TV. And Fabio was game. But halfway through the initial 210-foot drop, a wild goose flew into the coaster’s path and smashed into Fabio’s face. The impact gashed the model’s nose and killed the goose, whose broken body was later fished out of a nearby river. Fabio ended the ride with his face covered in blood (whether his own or that of the goose, no one could say).

The so-called “G forces” describe how much force the rider is actually feeling: a unit for measuring acceleration in terms of gravity. It also determines how much we weigh, as opposed to our mass (how many atoms make up our body). Weight is determined by multiplying an object’s mass by the force of Earth’s gravity. The G forces arise because a roller coaster is constantly accelerating: forward and backward, up and down, and side to side. This produces corresponding variations in the strength of gravity’s pull. For example, 1G is the force of Earth’s gravity: what the rider feels when the car is stationary or moving at a constant speed. Acceleration causes a corresponding increase in weight, so that at 4 Gs, for example, a rider will experience a force equal to four times his weight.

At high speeds, those G forces can be considerable. Fabio endured a lot of ridicule in the media after his encounter with the kamikaze goose; people were amused that the 6’3”, 220-pound hunk fared so poorly against a 22-pound waterfowl. But assuming the collision lasted a hundredth of a second, and the coaster was traveling at a speed of about 70 MPH, Fabio would have absorbed the impact equivalent of a hard tackle by football hall-of-famer Mean Joe Green, delivered with a force equivalent to a solid punch from heavyweight champ Mike Tyson. Yet not one reporter ever said, “That Fabio, he can really take a punch!”

So yeah: your roller coaster has a dark side: accidents and injuries do happen, and coaster-related (human, as opposed to goose) deaths number between two and four per year. Compared to the hundreds of millions of visitors who crowd amusement parks every year, this might seem insignificant; fatalities occur for about one in 450 million riders. But the federal Consumer Products Safety Commission reported in 1999 that there had been an 87% increase in amusement park ride injuries from 1994 to 1998, which it attributed in part to the steadily increasing acceleration forces generated by the rides. The newest coasters can reach top speeds of 100 MPH with G force ratings as high as 6.5. For comparison, astronauts typically experience 4 Gs while traveling up to 17,440 MPH on liftoff, and NASCAR drivers have reported feeling dizzy after experiencing 5 Gs. Coaster designers counter this by pointing out that astronauts and NASCAR racers experience sustained G forces; roller coaster riders are typically only exposed to high G forces for one second or less.

Of course, one can't completely discount human stupidity, either. Some of the most spectacular accidents occur because riders ignore basic safety precautions. Removing the safety harness can chuck a rider out of the car and send him flying through the air at high speeds. In 1996, at Six Flags Great America, a man wandered into a restricted track area to retrieve his wife’s hat, which had blown off in the high winds. A rider on the Top Gun suspension coaster kicked him in the head, killing the man instantly. The rider suffered a broken leg. Six years later, a rider on the Batman suspension coaster at Six Flags Over Georgia leaned out of the car and nearly lost his head when a rider in a train traveling in the other direction on an adjacent track kicked it. The man who leaned out of his car was killed immediately by the impact. And in a bizarre incident in May 2003, an 11-year-old girl choked to death on her own gum while riding a coaster at Six Flags Great America.

But the Euthanasia Coaster seems to focus on the more insidious kinds of physical effects; some doctors believe that the sharp jerks and jostles of high-speed rides could have the same brain-battering effects as professional football. The strong G forces can cause headaches, nausea and dizziness – possibly harmless, but also symptoms of mild concussion – simply because the body doesn’t have sufficient time to adapt to the constantly changing environment.

The effect can be similar to what happens to the brain during a car accident, or when a person is violently shaken. As the head whips sharply back and forth, the brain can pull away from one side of the skull and smash into the other side with sufficient force to rupture tiny blood vessels. The trickling blood accumulates in the small space between the brain and the skull, and the resulting pressure can lead to permanent brain damage or death if left untreated. In the summer of 2001 alone, three women suffered fatal brain injuries on roller coasters in California, although two of those victims had pre-existing aneurisms – a weak spot on a blood vessel in their brains – which ruptured during the ride.

None of these dangers are likely to dissuade any diehard coaster fans; that's just another part of the thrill. But take it from Fabio: a roller coaster can definitely hurt you. And the Euthanasia Coaster literally wants to kill you. At least first, it will give you the ride of your life.

Old Film of a Roller Coaster Accident - For more funny movies, click here

here, listen to this while I'm away

While you're waiting for fresh blogging fare at the cocktail party (it's coming soon! we promise!), let me point you to the hot new diavlog I did for BloggingHeads.tv, featuring me and author Mary Roach, whose latest book is the excellent Packing for Mars. Regular readers know I'm a longstanding fan of Mary's work, and she's just as fun and engaging over the phone as she is in print. We chatted about zero gravity (she got to ride on the Vomit Comit!), what freefall is really like during a spacewalk, the psychological complications pertaining to sex in space, Mary's foray into space toilet training, and she also had the chance to redeem the reputation of Enos the Space Chimp, unfairly maligned for masturbating during his NASA space mission. (Although if he had, Roach says, that would have given Enos the dubious honor of achieving first orgasm in space.) Go on, you know you want to give it a listen. And we'll be back soon with new posts before you know it.

coaster to coaster

Back in my Bohemian days as a struggling freelance writer in New York City -- before I went all respectable and got engaged and stuff -- my good friend Peri and I would occasionally play hooky from our daily responsibilities in the summers and head off to Coney Island for the afternoon. Sure, we'd stroll along the boardwalk with ice cream corns and scarf down "dirt water dawgs" for lunch, but the real attraction -- as it is for so many -- was the chance to ride the legendary Cyclone, Coney Island's signature wooden coaster, an official national landmark. It's quite an experience, and no small part of the thrill arises because the Cyclone was built before existing safety codes. While it's been upgraded a bit, those upgrades are decidedly patchwork in nature. I mean, they're still using the same 100-horsepower motor they used on June 26, 1927, when the Cyclone first opened.

If anyone's doing the math, that means the Cyclone turns 80 today -- talk about respectability! And there's going to be quite the party to celebrate. I learned about it via Majikthise, who also posted some fantastic photos from Saturday's annual Mermaid Parade. The day's festivities include a special "octogenarian's ride," in which a Cyclone "dream team" of local 80-something coaster enthusiasts will take the day's first run. The first 80 fans in line will get to ride free of charge -- no small savings, since a ride is now $6, compared to the 25 cents it cost back in 1927. There will be stilt walkers, a band, an appearance by "Miss Cyclone" (because what birthday party is complete without the cheesecake factor?), and the usual smattering of city officials that show up for such events.

I love the Cyclone, even though the entire structure is so rickety it feels like the bolts could come loose and the whole thing fly apart at any moment. (For all the sense of risk, the only time I was at Coney Island and a fatal accident occurred, said accident didn't happen on the cyclone.) So I was pleased to read in a Newsday article that the Cyclone goes through a routine daily checkup under the watchful eye of 64-year-old Gerry Menditto, a former electrician. His team is responsible for testing everything from the wheels to every inch of track. A couple of workers walk through the entire structure, striking the track with hammers. Any place that sounds tinny or hollow gets marked for repair. Broken bolts are replaced, as is cracked wood, and touch-ups of paint ensure the whole thing looks, if not brand spanking new, at least reasonably tidy. 

Depending on what you consider to be a bona fide roller coaster, such rides date back to 17th century Russia, when the locals built enormous wooden slides covered with ice that featured 50- to 60-foot drops. People would climb to the top, shoot down on wooden sleds, and crash into sand piles at the bottom. Catherine the Great was a huge fan of them, and had several built on her estates. Pretty soon the French caught on, but lacking the icy weather of Russian winters, they opted for waxed slides, and added wheels to their sleds.  By 1817, they'd started building wooden tracks, with cars locked in via wheel axles fitting into a carved groove.

The first coaster in the US was the Mauch Chuk Switchback Railway, a former mine track in Pennsylvania originally built to transport loads of coal down the mountain. When it fell into disuse, it was reconfigured as a tourist attraction. The Cyclone was designed by a man named Vernon Keenan, and cost between $146,000 to $175,000 to build -- a small fortune in 1927.

The top speed is only about 60 MPH, paltry compared to the high speeds most modern day steel track coasters can achieve, but it was pretty intense in the Roaring Twenties. That first drop is 85 feet, at a 60-degree angle; writer George Plimpton described it as "vertigo-inducing." The ride features six 180-degree turns, 6 drops, 12 changes of direction, ad 27 elevation changes. Famed trans-Atlantic pilot Charles Lindbergh was one of the first to ride the Cyclone, and declared the experience to be "greater than flying an airplane at top speed." You couldn't ask for a better testimonial than that, and the coaster was an instant smash hit. There are still several "clones" operating all over the country, but Coney Island's is the one true original.

I mention the specs, because the key to the thrill in any coaster design is not just the drops, but the sharp, sudden changes in direction. That's why the Cyclone is still a pretty intense ride, even if it's not the slickest, fastest coaster in the country. Even at that relatively modest speed, the jerking motions are strong enough to send any unsecured valuables flying. I once lost a favorite pair of sunglasses that way, and Menditto, the Cyclone's primary caregiver, says he has a box full of lost cell phones, wallets, wigs, and false teeth -- even an artificial finger. (Ew!)

The Cyclone -- and all other roller coasters -- can be more than just good clean entertainment, however: they're the perfect hands-on physics lab for introducing kids to the fundamentals of gravity, acceleration, potential/kinetic energy, and the like. Which explains why there are so many Web sites devoted to the physics of roller coasters; you can even build your own virtual coaster and have the coaster meter evaluate your design (I ranked a 6 my first try, but caught on fast and got a 9 on my second). Science teachers have absolutely no excuse for claiming they lack a lively, kid-friendly framework in which to discuss these concepts -- not that I've met any who did. Most science teachers are well aware of the potential of amusement park physics (also playground physics). 

Because there's so many excellent sites out there with information on the physics of roller coasters, I'll just touch upon some of the more interesting (to me) aspects, as they pertain to my beloved Cyclone. First, there's the matter of the wooden coasters, which resemble traditional railroad tracks in that the metal wheels of the cars roll on a flat metal strip bolted to a running track made of laminated wood. They're not as fast as steel coasters (the invention of steel tubular tracks completely revolutionized coaster design), and they're more rigid, so you don't get those complex twists and turns and spiraling loops that delight thrill seekers on more modern designs. Then again, the Cyclone sways a lot more.

(Jen-Luc Piquant reminds me that the French invented a wooden looping coaster in 1846, unveiled at Frascati Gardens in Paris -- the coaster worked up just enough speed to drive the cars through the upside-down loop. A similar design appeared in the US in 1885, called the Flip-Flap, but it closed in 1903 because so many passengers were developing severe whiplash from the sharp, jerking motions.)

The Cyclone also employs the traditional chain lift mechanism to lift cars up the initial lift hill, before the car is released to plummet down that first drop. (I'll just assume regular readers don't need a refresher course in gravity and potential vs kinetic energy.) The brakes are built right into the track, not on the cars, and hydraulics are used to kick the braking mechanism into action at the end of the ride. But the reason even an old ride like the Cyclone can still offer a few thrills is the way the constant changes in  speed, direction, and elevation can impact the human body. The smart people at How Stuff Works attribute this to the fact that a person's inertia is separate from that of the car. I'll let them explain:

"When a coaster car is speeding up, the actual force acting on you is the seat pushing your body forward. But, because of your body's inertia, you feel a force in front of you, pushing you into the seat. You always feel the push of acceleration coming from the opposite direction of the actual force accelerating you."

The effects are even more pronounced during steep drops at sharp angles, like that 85-foot, 60-degree angle first drop on the Cyclone:

"When you plummet down a steep hill, gravity pulls you down while the acceleration force seems to be pulling you up. At a certain rate of acceleration, these opposite forces balance each other out, making you feel a sensation of weightlessness -- the same sensation a skydiver feels in free-fall."

NASA's Vomit Comet operates on similar principles -- as does the Tower of Terror at the California Land Adventure Park, right next door to Disneyland. I spent the better part of Monday hopping between the two amusement parks with my former college roommate Shari and her family, who were visiting from Seattle. We took in the Indiana Jones ride, a river rafting ride, the traditional ride on The Pirates of the Caribbean (updated to incorporate an animatronic Jack Sparrow), and a Monster's Inc ride that will make no sense to anyone who hasn't seen the movie (like me). But the highlight was definitely the Tower of Terror. It features a facsimile of an old Hollywood Hotel service elevator run amok, rising to the top floor and then shooting straight down the "shaft" several times in a freefall. It's quite exhilarating; we went on it twice, and Shari's 17-year-old and 14-year-old sons enthusiastically declared the ride "totally sick." ("Sick" being the equivalent of "awesome." Apparently it's what all the cool kids are using as slang these days.) The boys have never ridden the Coney Island Cyclone, however. I think they'd think it was pretty sick, too.

the not so friendly skies

Over the last six months, I have come to loathe George Gershwin's "Rhapsody in Blue." I used to love it. But that was before United Airlines made a tinny, Muzak version its signature theme song. I have now spent so many hours on hold with United's  customer service department, that the merest hint of those opening strains of "Rhapsody" are enough to make me want to gouge out my eyes with a ballpoint pen while grinding my teeth in abject frustration and listening to my ulcer drip. I will spare you my long list of woes; after all, I'm not the only one who has suffered this week. (And really, I should have known better than to fly through O'Hare, a.k.a., the Portal To Hell, but in this instance, I had no choice. So naturally my bag got sucked into its bottomless vortex en route to the APS April Meeting in Jacksonville, and has yet to re-emerge.) Suffice to say that over the last six months, I've been traveling an awful lot, almost exclusively on United, and found myself, roughly 60-70% of the time, dealing with lost baggage (even on simple direct flights), rude or indifferent personnel, and constant delays, not just from weather (which is irritating but understandable), but mechanical problems or, say, the crew just not showing up. These days, it's unusual when the airline actually gets it right.

It's not just United either; the entire airline industry has begun a slow spiral into chaos, and not in an interesting, nonlinear phenomena kind of way. We are required to practically undress and unpack at security checkpoints, meekly submitting to having a complete stranger paw through our personal belongings at random because the person manning the X-ray machine mistook a few Power Bar Protein Plus food bars for, I dunno, sticks of dynamite or something. When we finally get on the plane, we must squeeze into tiny seats that make even my relatively slim self feel a bit crowded. Hardly any domestic flights serve meals anymore, and those that do ask you to pay through the nose for them (unless you're First Class, in which case, you've already paid for several mediocre meals with the higher fare). And when you arrive at your destination, there's no guarantee that your bags will arrive with you. When you lodge a complaint, the staff person will first try to blame you for the problem: "Well, did you check your bag 45 minutes prior to the flight? Because we can't guarantee anything after that." If your bag arrives damaged, the airline swears it isn't responsible, honestly, because you CHOSE to check your bag with them, after all, and anyway, it was a subpar piece of crap if it couldn't take a decent beating.

Okay, that last bit exaggerates a little, but I'm sure many people share my impotent rage at how bad air travel has become. Perhaps the most frustrating thing about all these problems is that we are powerless to wage any effective protest or even a boycott, because, well, sometimes you've just got to fly. We need another option. It's time for a revolution, comrades in science -- a technological revolution. While loudly venting my rage this morning in the APS press room, I jokingly demanded that these lazy quantum physicists get off their derrieres and make teleportation a practical reality ASAP. (Whenever someone asks the inevitable "What superpower would you choose?" I always pick teleportation, because I waste so much friggin' time getting from Point A to Point B.) Ben Stein, of AIP's media relations team, assured me scientists could do it now, "as long as you're willing to be teleported one atom at a time." I'd be willing, but be forewarned: we're gonna need an awful lot of bandwidth. The Internets could be down for awhile -- like, the remainder of your lifetime and far, far beyond.

So teleportation -- not really a viable option as yet. Maybe Madeleine L'Engle had the right idea in A Wrinkle in Time: we should tesseract! Actually a tesseract is a hypercube, whereas L'Engle's description in the book more closely resembles a wormhole. And when it comes to wormholes, all good sci-fi fans (especially Trekkies) know the drill: under Einstein's general relativity, it's theoretically possible to warp spacetime so much (given enough mass/energy) that it can bend in such a way to connect remote points (and times!) in spacetime. Sadly, it would take far too much mass/energy than is available in our solar system, possibly even our entire galaxy, to create such a fold. So I guess we're stuck with meekly enduring a thousand paper cuts of indignity from the airline industry every time we venture into the not-so-friendly skies.

That's not stopping physicists from continually testing and refining Einstein's seminal theory, however, as this morning's first plenary lecture proved. Francis Everitt of Stanford University was on hand to give a broad overview of the Gravity Probe B experiment and announce some preliminary results. For people who want the "news nugget" straight away, here's the gist: after a lot of delays and some unexpected complications, the measurement data indicate that (a) GR correctly predicts the so-called "geodesic effect" (i.e., how much the mass of the Earth is warping local spacetime) to within around 1%; and (b) they're having a bit more trouble with data analysis to measure the expected "frame-dragging" effect (i.e., whether or not, and by what degree, the Earth drags the fabric of spacetime with it as it rotates). But Everitt, while cautious, is "optimistic" that they have caught "glimpses" of the frame-dragging effect. That caution translates into another eight months of slogging through the data to account for unexpected anomalies and such, but he and his colleagues seem fairly confident that in the end, GP-B's results will mesh nicely (within the expected error bars) with Einstein's prediction.

Of course, there's a whole lotta backstory and other details to take in before one can truly appreciate  the significance of that tidy little summation. First, non-scientist readers mostly likely had no idea that there was a satellite called Gravity Probe B circling the earth for the last three years, collecting data in hopes of confirming a couple of key Einsteinian predictions. Stanford's official press release calls it "the most sophisticated orbiting laboratory ever created."

Per Sir Isaac Newton, the spin axis of a perfect gyroscope (assuming such a thing existed, which it didn't in the late 1600s) orbiting the earth would remain unchanged for all eternity. But Newton saw gravity as a force between objects. Einstein re-envisioned gravity as arising from the warping, or curvature, of spacetime. The earth orbits the sun because the sun's mass causes spacetime to curve and dip, and the earth's motion merely follows that curvature. That's the central tenet of General Relativity, and Einstein made several predictions that could be used to test the accuracy of his theory.

One was confirmed almost immediately: Einstein said that a ray of light passing near the sun would be deflected by a certain degree, because the sun's mass would warp the surrounding spacetime and the light ray would follow that curvature. This effect would be observable during a solar eclipse, when the sun's light was temporarily blocked. And indeed, two years later, in May 1919, two separate scientific expeditions -- one in Brazil and another on an island off the coast of West Africa -- observed just such a deflection during a solar eclipse.

Einstein also predicted that the earth's mass would warp its surrounding spacetime, and that it would "drag" the fabric of spacetime by a certain degree as it rotates. Those last two predictions are the reason Gravity Probe B was first conceived in 1959 by two Stanford scientists named George Pugh and Leonard Schiff. The idea was to precisely measure the displacement angles of the spin axes of four different gyroscopes-in-space over the course of a year and then compare that data with Einstein's predictions. But the instrumentation and associated technologies just didn't exist back then to build such a complicated system. Here's just a few things they needed:

• Wobble-free gyroscopes. These are much larger versions of the spinning toys many of us played with as kids. (You can still buy them in science-type stores.) GP-B scientists did this by creating the world's smoothest, most perfect spheres, only surpassed in their perfect roundness by very dense neutron stars.
• Incredibly sensitive and precise sensors capable of measuring something the width of a human hair from about a mile away, because that's how tiny Einstein's predicted frame-dragging effect is expected to be. So they had to wait for the invention and subsequent development of Superconducting Quantum Interference Device (SQUID) based sensors to measure those tiny magnetic variations.
• A really, really big thermos. Seriously. They call it a "dewar," and it's roughly the size of a minivan, only it's a minivan filled with liquid helium to ensure that the entire gyroscope assembly housed within stays cold enough to function properly for the full 16 months with the needed precision: 1.8 degrees Kelvin.
• There's so much more technological development that had to be developed to make the mission remotely feasible (never mind successful), including the entire Global Positioning System; a souped-up telescope to get the most precise focus on the orienting star; a suspension system capable of keeping the gyroscopes' spinning rotors from making contact with the walls (which would naturally destroy the equipment); and a technology capable of tracking the path of the equipment inside the probe itself rather than the path of the orbiting spacecraft. (Basically, the gyroscope orbits the earth in a state of perfect free-fall because the body of the craft shields it from outside disturbances like friction and magnetic fields.)

So, 40-odd years and some $700 million after it was first proposed, Gravity Probe B has returned with some preliminary answers. There's really little doubt about the confirmation of the geodesic effect, according to Everitt: "[It] is clearly seen even in the unprocessed scientific data." (For hard-core types who want the numbers, Einstein predicted that geodetic warping around the earth would cause the spin axes of each gyroscope to shift by 6.606 arc-seconds, or 0.0018 degrees.) But frame-dragging is a much tinier effect; the prediction is that the twisting of earth's local spacetime would cause the spin axis to shift by 0.039 arc-seconds, or 0.000011 degrees. That's much harder to measure accurately -- particularly since the "signal" indicating relativistic effects of gravity around the earth must be extracted from a bunch of background noise. Ergo, that's where the biggest delays have occurred in terms of analyzing the data.

There's a whole host of reasons for this, but one of the most certain things about space-based missions is that, no matter how thoroughly you try to predict every conceivable complication, something unexpected is bound to happen. (I'd wager United Airlines can relate.) That's what happened with Gravity Probe B. First, the initial in-flight verification phase of the project took twice as long as expected. Then, as the experiment was running, random protons from a solar flare damaged some cells in the on-board computer memory, so the system automatically switched to the backup computer. Ensuing computer reboots in response to random radiation strikes meant there were interruptions in the data streams. (Segmented data is much harder to analyze; you've got to account for the breaks in data and so forth.)

The GP-B scientists also overlooked a tiny electrostatic "patch" effect in the gyroscopes. These patches can cause the gyroscope to "wobble" a bit as it spins, much like a football that isn't thrown in a perfect spiral. The scientists were able to model and predict that wobble. What they didn't expect was that the pattern/motion would subtly shift over time. They accounted for electrostatic patches on the rotor, said Everitt, but forgot about the housing, and it turned out to be significant enough a discrepancy to add those 8 months to the data analysis. Those same electrostatic patches also caused small torques in the gyroscopes' spin axes, and the resulting slight changes in orientation could be mistaken for the relativity "signal" that GP-B is designed to measure. Nobody wants to announce a "false positive," so the collaboration is taking its time and being extra careful to ensure they're seeing what's really there, not an anomaly masquerading as a frame-dragging effect.

Gravity Probe B has taken some flak lately for the long delays and high cost of the project: when the government spends $700 million, gosh darn it, they want answers quickly. But science doesn't always proceed according to a predetermined schedule (in fact, it rarely does). That's just not the nature of the beast. Personally, if I spent $700 million on an experiment, I would want the scientists involved to take as much time as they think they need with the data before announcing an official final result. No point spending all that cash if you're not going to get a reliable result.

Everitt, not surprisingly, agreed with that assessment when I brought up during a brief discussion with him after his talk, pointing out that the folks who worked on GP-B's predecessor (Gravity Probe A, natch) had expressed surprise that the B team expected to publish their results so soon after collecting the raw data. "This is a very different game from pure astronomy, not better, not worse, just different," he said, citing the fact that astronomers can quickly publish their images from the Hubble Space Telescope and worry about more specific analysis later. The GP-B, on the other hand, is looking for two very small numbers given a very small margin for error. "So we'd better not get either one wrong," said Everitt. "Deliberateness is the name of the game."

So, okay, we got some interesting new insights into general relativity, and as a bonus, some nifty new technological toys out of it for future missions. It's still a fair question to ask, if there's already strong evidence supporting GR's predictions, why continue testing it at all? Well, because that's pretty much what science is about -- a theory is only as good as its last experimental confirmation. Einstein was brilliant, but he wasn't infallible. It's perfectly plausible that there could be an error in one of his predictions, and that Gravity Probe B or subsequent experiments could find it. And if/when that happens, a lot of newspaper headlines will scream, "EINSTEIN WAS WRONG!" while crackpots everywhere secretly feel vindicated because, heck, they've been saying this for decades and now maybe someone will consider their wacky alternative theory.

The very British and wryly laconic Everitt declined to comment directly on the implications -- best case scenario or worst case scenario -- of GP'B's expected final results. "I don't believe in worst case scenarios," he said in answer to the the latter, adding, "We have only one job: to do the experiment right. It's not my job to worry about the implications." But I'll go out on a limb here and predict that, should the worst case scenario transpire and Einstein had a wrong prediction for the frame-dragging effect, all it will actually mean is that one aspect of GR needs to be fine-tuned/corrected in light of experimental data unavailable to Good Ol' Al back in 1917. The theory itself will survive quite intact, because so many other predictions have been experimentally confirmed already. It's not the proverbial house of cards; by now, GR is pretty darn robust as scientific theories go.

About the only place it doesn't work is at the subatomic scale, and, well, a lot of very smart people are working on reconciling that problem even as I type. Once they get a handle on that whole Theory of Everything problem, I hope they'll turn their attention to the much tougher task of fixing the airline industry.

balancing act

Things have been a bit quiet at the cocktail party this past week, I know. That's partly because I wrote another "Random Walks" column for 3 Quarks Daily over the weekend, about shock-rocker Alice Cooper and his connection to medieval mystery plays -- you know, something wholesome for the Easter holiday that the entire family can enjoy. Another reason is that my entire life has been subsumed by packing: packing for various trips, and packing up my home, not to mention sifting through the accumulated detritus of my life in DC deciding what to discard and what to transport with me to sunny La-La Land. (It's frankly tempting to just ditch everything and start over from scratch, except I've grown quite fond of certain items that might prove difficult to replace.) Tonight I'm packing for a two-day "Communicating Science" workshop in Lincoln, Nebraska -- where, no doubt, the dreaded "framing" topic will come up -- after which I fly directly to Jacksonville, Florida, for the APS April meeting. So expect lots of blogging from Friday through Tuesday about all kinds of nifty science-type stuff.

In the meantime, commenter Jongleur has chastised me for not mentioning British physicist C.V. Boys in the bubbles post. Mea culpa, although, you know, these posts aren't meant to be exhaustive. I realize their sheer length might suggest otherwise, but it's still just a blog, folks. Nonetheless, Charles Vernon Boys is one of those scientists who made a quieter mark on physics than some of his peers, and it's nice to bring him out of history's shadows on occasion. He was the son of an Anglican vicar who earned a degree in mining and metallurgy while teaching himself advanced mathematics.

Jongleur mentioned Boys because, in the late 19th century, he gave a series of public lectures on the properties of soap films at the London Institution. (Michael Faraday started the whole public lecture tradition in 1826.) Those lectures became the classic book, Soap Bubbles: Their Colours and the Forces Which Mould Them. In Boys' day it was the epitome of scientific popularization, and no wonder, since it was filled with creative, crowd-pleasing tidbits like explaining "wine tears" -- the pattern that forms when wine climbs up the glass and falls back down, making it seem as if the glass is "weeping."

He also demonstrated the use of capillary action to raise or lower liquid levels in a tube, how to build water bombs out of paper folded into a small origami box, and explained how it might, indeed, have been possible for men to go to sea in a sieve, per the nonsense lyric by Edward Lear: "They went to sea in a sieve, they did,/ In a sieve they went to sea:/ In spite of all their friends could say,/ On a winter's morn, on a stormy day,/ In a sieve they went to sea." It's all a matter of getting the right surface characteristics for the sieve wire and mesh size so that surface tension could prevent water from entering the holes. Jen-Luc Piquant also directs our attention to a modern-day C.V. Boys, Maarten Rutgers, a soft condensed matter physicist at Ohio State University, who is known for inventing his own apparatus to construct gigantic soap bubble films in science museums around the country -- like this four-story flowing soap film he made for the Carnegie Science Center in Pittsburgh.

Boys wasn't just about bubbles, however. He was, first and foremost, an ingenious experimentalist who liked to invent handy measurement devices. For instance, while still a student at the Royal School of Mines, he invented a mechanical device for plotting the integral of a function (see "The Calculus Diaries" series of posts in the sidebar for my own preliminary foray into integrals).

He also played around with torsion balances and conducted experiments to more accurately measure the gravitational constant (a.k.a., "Big G"). There's a long history of such experiments, dating back to Sir Isaac Newton. In his Principia, published in 1687, Newton asserted that on level ground, a "plumb bob" would hang vertically because it was attracted to the Earth's center. However, if there was a large mass nearby, like a mountain, the bob would be pulled slightly off its vertical path because of extra attraction toward the mountain.

In the summer of 1774, Nevil Maskelyne, Astronomer Royal, spent four months in the Scottish highlands testing Newton's assertion on Mount Schiehallion. (It should be noted that he wasn't happy about it, but apparently no one else could be persuaded to go to Scotland, even for the sake of science.) And it worked! The little plumb bob was indeed attracted to the mountain. After Maskelyne presented his results to the Royal Society on July 6, 1775, the mathematician Charles Hutton used the data to determine the mean density of the Earth. Hutton was within 20% of the current accepted value.

Physicists have been attempting to measure "Big G" more accurately ever since. They got a big boost with the invention of the torsion balance in the late 18th century, a device intended to measure very small forces. (Whether it was invented by Charles Coulomb or the Reverend John Mitchell is the subject of occasional rancorous debate.) It's simplicity itself in concept: the torsion balance is little more than a horizontal beam with small lead balls at each end. The beam is suspended from its center by a thin torsion wire. If you place a large lead ball near each of the smaller balls (in the same horizontal plane), the resulting gravitational attraction will twist the torsion wire in the same direction. And the angle of the twist can be measured to determine the amount of force acting upon it.

Henry Cavendish was the first to use the torsion balance to measure Big G and determine the mean density of the Earth in 1798. But that's no reason not to keep repeating the experiments with ever-more-sensitive equipment and conditions! The Earth could go on a crash diet at any time! So 100 years later, Boys improved on the torsion balance used by Cavendish by (a) making it smaller, and (b) replacing the copper torsion wire with quartz fiber (different materials have different levels of elasticity and therefore react differently to the twisting motion).

With these improvements, Boys was able to measure Big G to about 1 part in 1000, a singular improvement, but he struggled to improve it further because the results were marred by all the external vibration. His experiment was housed in an underground tunnel, and what with students traipsing about and coal deliveries and the like, it was tough to weed out all the "noise." Eventually he moved the experiment to Oxford, which was a bit quieter, but there was still a lot of traffic on the cobblestone streets. Boys found it best to do the work on Sunday mornings, and while he did get a slightly better measurement, it took four years, during which he took no holidays, and he abandoned further work, claiming exhaustion.

As recently as 2000, physicists were still trying to more accurately measure Big G -- and getting conflicting answers.  As we saw with the case of Maskelyne and Hutton, one of the "applications" of knowing the gravitational constant is that it enables scientists to determine exactly how much the earth "weighs." Doing so is no mean feat, since gravity is so much weaker than the other fundamental forces. As Boys discovered in his London and Oxford experiments, the apparatus must be completely isolated and performed in a vacuum, although almost nothing can completely shield it from minute outside gravitational influences. (In fact, during one such experiment at the University of California, Irvine, the experiment showed tiny "wriggles" in the data which turned out to be caused by the sprinkler system just outside the physics lab building.)

And that's today's foray into the annals of physics history. Charles Vernon Boys: not just about the bubbles.  Someone's got to carry on the tradition of Boys and Maskelyne the Reluctant and carry out the tedious dirty work of physics. It's nice to have them remembered now and then.

breaking the waves

Is it just me, or did Bloglines go completely bonkers over the weekend, posting and re-posting all the most recent entries on several different blogs, including Cocktail Party Physics and my occasional weekend getaway, 3 Quarks Daily? Perhaps the system is rebelling against the cold snap that enveloped the Northeast this weekend. It certainly came as a shock to my system, after 10 days in Los Angeles and Hawaii. I comfort myself by recalling the warm sunshine, refreshing breeze and  sounds of the waves breaking on Waikiki beach from my hotel balcony. Just think, a little over a week ago, I was basking in the sun, watching surfers frolic in the ocean -- and would-be surfers practice the basic mechanics on the shore, under the watchful eye of a very peppy, bikini-clad instructor.

Sadly, I didn't have the chance to take any surfing lessons myself, which is a shame, because I've always wanted to learn. (Note to self: must stop living in frigid climes.) Among other things, there's an awful lot of fundamental physics involved: potential and kinetic energy, surface tension, friction, buoyancy, hydrodynamics, and good ol' Newtonian gravity/laws of motion. The Exploratorium has an excellent summation of all that basic physics here, including all the factors that conspire to make the "perfect wave."

There's also some less fundamental science associated with surfing, in the form of acoustic waves. The bigger the wave, the more sound you get -- a statement that seems, like, totally obvious to any diehard surfer. And it's not just the waves we can hear breaking along the shore, although those are scientifically interesting in their own right. Human hearing is rather limited in range, from 20 Hz to 22 kHz, but sound waves exist far beyond that. We can't hear ultrasonic pulses, like bats use for echolocation, and we can't hear the ultra-low-frequency waves of acoustic energy (infrasound) employed by elephants or tigers, for example. Wind, water, earthquakes, avalanches, tornadoes and hurricanes all produce infrasound as well. Most of us aren't aware that Nature has an entire palette of sounds that play constantly, just beyond our ken (although psychologist Richard Wiseman of the University of Hertfordshire has speculated that the odd sensations people believe are caused by ghosts are actually a subconscious "sensing" of infrasonic vibrations). To an acoustician, there's no such thing as perfect silence; to them, what we think of as "silence" can be downright loud.

Volcanoes, for example, exhibit seismic rumblings -- low-frequency audio waves vibrating through the medium of the earth's crust -- and make a lot of noise when they erupt (the shock wave phenomenon). But they also produce infrasonic waves via combinations of any number of underlying physical mechanisms, depending on the type of volcano. Scientists have known this since the late 19th century, when the Indonesian volcano, Krakatoa, erupted on August 27, 1883. The eruption produced a flurry of infrasonic waves, the acoustical equivalent of "an earthquake in the air," per Simon Winchester, author of the 2003 book, Krakatoa: The Day the World Exploded.

This makes the infrasound emissions -- or "vocalizations" -- of active volcanoes a fascinating subject of study for Milton Garces, an oceanographer at the University of Hawaii, Manoa. Garces is a colorful guy. Most acousticians have a touch of the maverick in them, almost by necessity: if you're trying to study the propagation of acoustic waves, you've got to go where the waves are happening, even if that leads you to remote Mayan ruins or the foot of a very-much-active volcano. Garces is no exception. When he's not exploding missiles at the White Sands Missile Range in New Mexico (to better study the infrasonic waves that result from the explosion), he's setting up infrasound sensor arrays around volcanoes in Ecuador, or Japan's Kyushu Island. And yes, he has been caught napping -- literally! in a Toyota Corolla! -- in the vicinity of a volcanic eruption, resulting in some harrowing, ash-choked moments before he was able to drive to safety.

In short, Garces is the adventurous type, and a bit of a risk-taker -- traits that have served him well in his research, since all the best science requires a certain assumption of risk. Plus, he's got this whole "Antonio Banderas with a PhD" thing going. It was fascinating to watch the audience's fluttery reactions at the ASA meeting as he waxed poetic about giving his beloved volcanoes a "voice" while playing sound clips of recorded infrasonic waves (with the pitch shifted by a factor of 400 or so to make it detectable to the human ear). I mean, if those sound files are anything to go by, a volcano's "voice" resembles severe gastric distress, and yet Garces had us all marveling at these vocalizations as if they were the Song of Songs. (Rest assured, I am utterly devoted to my betrothed, that Fourier-transform-spouting cosmologist, who can certainly hold his own against Garces on the Charmingly Attractive Scientist front. But Jen-Luc Piquant remains a free agent, and is a sucker for a Spanish accent. So is Wired, apparently; in a recent article, reporter John Geirland raved about Garces' "trim" physique and "glowing hazel eyes." Um, drool much, Mr. Geirland?)

So Garces is seriously mediagenic. (Jen-Luc calls him the Volcano Whisperer, lovingly coaxing the desired infrasonic data from the groaning depths of a coy volcanic mountain reluctant to reveal her darkest secrets.) Frankly, he knows it, and isn't afraid to "work it" a little in order to drum up some much-needed media exposure for his area of expertise. And kudos to him for doing so. Infrasound was all the rage from World War I through the 1950s, when it was used to monitor Soviet nuclear testing on the other side of the globe. But the technology was abandoned in the late 1960s in favor of satellite monitoring. It languished as an academic backwater for the next 30 years, and only now is it coming back into its own -- thanks in part to engaging, media-friendly scientists like Garces.

Sure, the research is way cool, dude, but there's a practical side as well. Infrasound is potentially a more accurate barometer of volcanic activity than traditional seismography. Ash clouds, for instance, are a serious aviation hazard. In the last 20 years, more than 200 aircraft have flown into clouds of ash from unexpected volcanic eruptions. This is very dangerous because the silicon-based particles from the eruption can enter jet engines and melt, impairing or even destroying the engines. Per the aforementioned Wired article, catastrophe was narrowly averted in 1982, when a Boeing 747 with 240 passengers on board flew through a plume of ash from Indonesia's Galunggung volcano at 37,000 feet. All four engines shut down and the craft plummeted 25,000 feet before three of those engines finally restarted.

Combining seismic data with infrasound monitoring could make it easier for scientists to tell when a given volcano is about to blow, whether ash will be ejected, and hopefully avoid such near-catastrophes in the future. Garces and his cohorts have developed a prototype system called Acoustical Surveillance for Hazardous Eruptions (ASHE), deployed in Ecuador in January 2005, because the region has numerous active volcanoes in a relatively small geographical area. They've used it to identify specific infrasonic signals associated with explosions, seismic activity, and flows of debris. The good news: there may be distinctly different infrasound signals for volcanic eruptions that produce ash, and those that do not.

You're probably wondering at this point what Garces and volcanoes have to do with surfing, which is where we started out. No, I'm not aimlessly rambling -- not much, anyway. It's all about the infrasound, baby! For Garces, it's a natural connection, since he is also an avid surfer. (He's probably one of those daring sorts who jet-ski out to the oceanic wilds so they can catch the "big waves.") It just so happens that breaking waves also produce infrasonic signals. Garces' new work exploits this feature to (hopefully) achieve Real-Time Surf Infrasonic Monitoring, or, as he prefers to phrase it, "the deep sound of one wave plunging."

Garces is specifically studying breaking waves along Oahu's North Shore, widely deemed to be a surfer's Mecca. There are three types of wave "breaks" that produce infrasound: plunging breaks, cliff breaks, and reef breaks, and Garces' latest work focuses on the latter. He is attempting to isolate the sound of a single wave in the process of breaking -- essentially, he's tracking progressive wavefronts -- with acoustically sensitive pressure sensors deployed along the ocean floor, augmented with conventional seismography. He hopes to use the collected raw data to extract useful information about wave height, for example, to better identify potential hazards to surfers (and, one assumes, swimmers as well). 

It's trickier than it seems: such predictions currently rely on the observations of surfers themselves to determine wave heights. True, there are sensor-equipped buoys in the cove designed to collect that information, but the data are insufficient to make accurate predictions.

I initially found this quite surprising, since a similar system works quite well along the coastline of San Diego, where the Scripps Institute deploys a similar set of buoys, and crunches the raw data using clever algorithms to separate the meaningful signals from background noise. This enables them to plot the direction, speed and curvature of incoming waves to determine the location of the sound source, and to make more accurate predictions. So why wouldn't it work on Oahu? Fortunately, I chanced to strike up a passing conversation with Geoffrey Edelmann, an acoustician at the Naval Research Laboratory, after the infrasound session, who explained that it's easier to establish directionality along San Diego's far more sheltered coastline than it is in Hawaii, where wave directionality isn't clear at all -- they're literally coming in from all directions at once. So the San Diego algorithms just don't apply; scientists can't make the same set of underlying assumptions.

Anyway, Garces' latest project is still in its earliest stages, and his team will continue collecting and analyzing data throughout this winter. But if his hunch turns out to be right, infrasound could end up being a very useful tool for oceanographic monitoring as well. He reported some intriguing preliminary results: there appear to be seasonal changes, with certain areas becoming more acoustically active than others at certain times of year.

Perhaps surfing does have its seasons, even in Hawaii; those of us living in more variable climes have a far different concept of "seasonal." Except for certain people in Cleveland, apparently, according to an article in today's New York Times.  These people love to surf so much not even frigid temperatures and (occasionally) raw sewage can keep them away from Lake Erie. They don wet suits, wear goggles, and learn to avoid ice chunks the size of bowling balls. Ouch. (Hat tip to Orac at Respectful Insolence, who observes, "There are no depths of craziness they won't plumb.") Those unwilling to face such hardship can always avail themselves of the growing number of indoor wave pools/water park resorts sprouting up all over the nation, like Wisconsin Dells.

But really, it makes far more sense to switch to something like snowboarding, a la Olympic gold medalist Shaun "The Flying Tomato" White, who skateboards in the summers when snowboarding is out of season. Both skateboarding and snowboarding have their own underlying physics principles (not identical, but similar); check out discussions of the topic here and here, and marvel all the more the next time you see White performing those jaw-dropping airborne flips and 360-degree rotations. Athletes like White have an intuitive grasp of the physics behind their sports. They wouldn't excel  so spectacularly otherwise. But what is the sound of a single snowflake falling onto the slick, icy surface of the half-pipe? Scientists like Garces who study infrasound could probably figure out the answer.

the importance of being nitpicky

Jen-Luc Piquant and I are all jacked up on caffeine and frustration-derived adrenalin at the APS April meeting here in Dallas, after a fruitless hours-long effort to find a high-speed internet connection that works consistently. We would like to state uncategorically that the Dallas Hyatt Regency has the worst high-speed wireless internet connection we have yet encountered in our many jaunts to physics conferences.

The signal is weak, and sometimes disappears altogether. Sometimes one gets a signal, but no connection. And when one does get a connection, it is unbearably slow, so much so that we briefly considered resorting to dial-up. (Oh, the horror!) There are rumors of one good "hot spot" in the hotel bar, right by the piano, that seems to work well, so whenever sessions let out, there is a mad rush to that area by physicists desperate to check their email before the next set of papers. It looks suspiciously like a pre-arranged flash mob, when in fact it's more like a weird kind of emergent behavioral phenomenon dictated by dire circumstances of Internet withdrawal.

And this is why we have been delayed in posting something about the ongoing conference. "Really," Jen-Luc huffs, in haughty high dudgeon, "How can we possibly blog under such barbaric conditions?" Nonetheless, we shall try, although we might lack our usual polish. Because while there has been much wailing and gashing of teeth in the press room about the lack of "real news" at this year's meeting, that doesn't mean there isn't a bunch of really cool stuff going on. It's just hidden in the nooks and crannies, rather than displaying itself brazenly in the center of the town square -- although for some reason, all the sessions on cosmology and dark matter/energy have been standing room only. (People were actually standing on chairs in the hall to hear Cosmic Variance's own Sean Carroll talk about "the future of theoretical cosmology," which was delivered with characteristic panache.)

It occurred to me today that perhaps we focus a bit too much, as science writers, on major results or breakthroughs -- so much so that we miss a lot of the tiny, incremental breakthroughs that are constantly taking place all the time, year after year, which eventually add up to the major "news worthy" results that everyone makes such a fuss about. But what about all the other forgotten, unsung experiments (or planned experiments that sadly never saw the light of day), the fascinating conjectures, colorful minute details, and amusing anecdotes? These, too, are a seminal part of physics, and a big part of what makes the field so fascinating.

Okay, I know I sometimes whinge about certain scientists being excessively nitpicky about minute technical details. That's relevant to a discussion of public communication of science. But in the actual practice of science itself, those nitpicky elements are indeed absolutely crucial. And while it's hard to "sell" those kinds of stories to the press, it's not impossible.

I was reminded of the importance of being nitpicky in physics at a press conference yesterday on experimental attempts by Eric Adelberger's group at the University of Washington to find violations in one of the most fundamental aspects of special relativity: Lorentz invariance. (For more specific detail about this experiment, and several others, go here.) That's the bit about the laws of physics being the same for all observers, regardless of frame of reference. It's something we all kind of take as a given these days, but before 1905, it was by no means accepted. Or even obvious. Physicists of prior eras firmly believed that light would show the effects of motion, but experiment after experiment failed to produce this result, with the final nail being driven in the coffin when Michelson and Morley (once again) failed to observe this prediction. But experiment after experiment has validated this particular aspect of special relativity.

So, if special relativity, as a theory, has already been confirmed, repeatedly, one might ask, why even bother to keep testing? The same question came up earlier this year with the announcement of the most precise experimental confirmation to date of another Einstein workhorse, E=mc<2>. To someone unversed in the scientific method -- and they are legion, as evidenced by all those folks who think saying evolution is "just a theory" means it's incorrect -- it seems like a waste of time to keep testing something we already know is right.

This is why: one of the best things about physics, is that it never assumes it has all the answers of the universe -- just the best answer we can verify for now. The longer a theory is in play, and the more experimental evidence is compiled to support it, the more likely it is that this theory is correct... and the more emphatically physicists will defend it. But there is always the tiniest possible chance that some experiment, somewhere down the line, will find a violation of a basic principle at, say, the eighth decimal point. And that point, as Feynman would say, is when things become "very IN-teresting." Even a slight departure from the expected behavior could signal the start of a new line of inquiry that might one day revolutionize our understanding of the universe. Adelberger's group designs all kinds of experiments to test a wide range of established physics theories. And it just seemed natural to ask: what would it take to dislodge special relativity, or at least shake up its foundations? (The answer appears to be, quite a lot. And we haven't found it yet.)

Granted, this is not the kind of thing that tends to make non-scientists sit up and take notice. Back in 2000, at the APS April Meeting in Long Beach, California, I attended a press conference reporting on recent conflicting measurements of the gravitational constant, affectionately known as "Big G."  Adelberger's people made one of those measurements. The scientists on hand were excited about the discrepancy -- to them this was fascinating physics, for good reason -- but to the assembled reporters, and to any lone members of the public who might have wandered by, it all seemed irrelevant. Finally, one reporter from a local newspaper asked (and I paraphrase), "So, why even bother doing this experiment, if you already have a reasonably good measurement that works just fine for all practical applications, and won't be affected at all by this bit of improvement in our knowledge?"

There were many ways the researchers could have answered this question -- most obviously, it could become relevant as theoreticians come closer to devising a theory of everything that incorporates both gravity and quantum mechanics --  but they froze, like deer in headlights, until one of them said, "Um, because it's FUN!" I found the comment charming, actually, because he clearly had enjoyed working on this problem, and it showed. But I was in the minority. Spending precious research dollars re-doing centuries-old experiments so you can more precisely measure a fundamental constant to yet another decimal point sounds a bit dodgy to the average taxpayer.

Fortunately, the press did find an angle: "Earth loses weight!" a BBC News headline screamed, and media outlet after media outlet followed their lead. One of the "applications" of knowing the gravitational constant is that it enables scientists to determine exactly how much the earth "weighs."  Doing so is no mean feat, since gravity is so much weaker than the other fundamental forces. Any measurement experiments must be completely isolated and performed in a vacuum, although almost nothing can completely shield it from minute outside gravitational influences. (In fact, during one such experiment at the University of California, Irvine, the experiment showed tiny "wriggles" in the data which turned out to be caused by the sprinkler system just outside the physics lab building.)

Context is everything, of course, and there's an excellent account from 1998 about the history behind all of this by David Kestenbaum in Science magazine. A physicist named Henry Cavendish was the first to make this measurement -- by candlelight, no less, how romantic --using a small suspended lead barbell hanging from a twisting fiber. The tiny motions of twisting that he observed revealed the strength of gravity between the two masses in his experiment: two weights the size of bowling balls.

Some version of Cavendish's torsion balance is usually employed to measure G ever since. In fact, if you're patient enough, and reasonably well-versed in physics, you can undertake your own basement experiment to make this exact same measurement. If nothing else, it should serve to demonstrate just how impressive Cavendish's achievement was. 

The new measurements, while not completely in agreement with each other, nonetheless had a major impact on the overall weight of the earth. Our pretty blue planet "lost" something on the order of 10 billion billion tons overnight -- just by tweaking the parameters of one tiny constant by a few increments here and there. "Weight," apparently, is somewhat "relative" as well. And that gave reporters the hook they needed. In fairness, it should be noted that even many physicists are a bit blase about things like making more accurate measurements of G. In Kestenbaum's 1998 article, Clive Speaks of the University of Birmingham in England is memorably quoted as saying, "Nobody gives a damn about Big G." (Tell that to the Earth, which lost several dress sizes in 24 hours and gained a big boost in self-esteem.) Kestenbaum himself likened these kinds of experiments to a sort of extreme sport in physics: "the Mount Everest of precision measurement." Why keep making these measurements of G? Because it's there. Who cares if thousands of others have climbed that mountain before?

Of course, sometimes what you get out of a meeting isn't so much from the sessions themselves, or even the organized press conferences, but from the random casual encounters and conversations with scientists that invariably take place. For instance, while hanging out in the hotel lobby coffee bar last night, I started chatting with a few random cosmologists, who graciously answered my sophomoric "why is the sky blue" questions about why entropy equations keep turning up in everything from economic theories to parabolic arches -- and I thank them for their patience and clarity in doing so. Sure, the laws of physics are universal and all, and should therefore apply regardless of the system. But they said that there does seem to be something special about the laws of thermodynamics; they are deemed least likely to be proven wrong by future experiments. (I'm afraid I was just the slightest bit tipsy and am thus a bit fuzzy today as to why that is. So perhaps this isn't the best example of a positive educational encounter.) Which doesn't mean those won't continually be tested, at least by would-be inventors of free-energy machines.

I hope if nothing else this post will give any non-scientists who are reading this a small sense of why scientists are so obsessed with fine details. Sure, it can be annoying in a casual social setting, or when you're trying to make a much broader point that gets sidetracked by an argument over one tiny choice of wording. But there's a positive, flip side to that particular coin. That same precision and attention to detail has given rise not just to grand theories about the universe, but the inner workings of most modern technology. Except, of course, the wireless network at the Dallas Hyatt Regency. Whoever set that up was clearly not nitpicky enough, and we are paying the price for their slackerdom. A pox upon them, I say. Where are the nitpicking physicists when you need them?

fear of flying

I was a voracious reader as a child (I still am, whenever my frenetic schedule permits). I'd read anything you put in front of me, including cereal boxes, appliance manuals, and Monopoly instructions. One of my earliest memories is sitting on my father's lap, all of four years old, trying to read his latest issue of Time, although it must be said that my comprehension of the weighty matters contained therein left a lot to be desired. I also plowed through a children's encyclopedia collection that my parents kept in the house for our edification. My favorite was the volume on mythology; I had a particular affinity for the tragic figure of Icarus.

You remember the tale: he and his father, Daedalus, were exiled onto a deserted island. Daedalus fashioned two pairs of wings, affixed to the shoulders with wax, so they could escape their island prison by flying into the air like birds. But Icarus became so exhilarated mid-flight about defying gravity that he ignored his father's warnings about flying too high. He flew too close to the sun. The heat melted the wax, the wings came loose, and poor Icarus plunged to his death in the waters below.

To my shy and rather timid young self, the lesson was obvious: it's far preferable to keep one's head down and lie low, rather than try to fly and risk crashing ignominiously to earth. It was a very long time before I overcame my innate "fear of flying" and realized that life is all about taking risks. What's that catchphrase from the film, Strictly Ballroom? "A life lived in fear is a life half lived." At some point in my adult life, I decided that half lives are for radioactive materials, not for me. That's one reason I was able to assume the risk of becoming a science writer and rising above a long-standing irrational fear of physics.

I was reminded of Icarus over the past few days. On Sunday, NPR's Weekend Edition aired a short five-minute interview with me about my book, Black Bodies and Quantum Cats. As a result, I spent the day fielding calls and emails from friends -- and a few long-lost acquaintances, one of whom expressed surprise that I'd ever amounted to anything -- and watching my book skyrocket up Amazon's mysterious ranking system, a phenomenon that is actually known at NPR headquarters as "the NPR Effect." (Physicists should get right on that bit of research.) By the end of the day, the story was the top emailed article on NPR's Web site, so clearly it struck a responsive chord with the listeners. But even awash in the glow of such modest success, I couldn't help feeling anxious and apprehensive about flying too close to the sun; Icarus lurked at the back of mind.

The inevitable crash was not long in coming. The linked page also includes a short excerpt from the book, on roller coasters and the infamous 1999 incident where male model Fabio was hit in the face by a wayward goose mid-ride. It includes an abridged explanation of the various forces at work on a roller coaster ride, including the so-called "g forces." Unfortunately, as one alert reader/listener (whom I shall call "Z") pointed out via email that evening, my summation is not quite right.

Here's the gist of his -- and it's always a "he," for some reason -- points: First, mass is not related to the number of atoms (although I've seen it described as such in more than one place, so clearly a broader correction is needed beyond my book): it's a measure of the inertia of a given object, that is, its tendency to stay at rest or move uniformly in a straight line, which also determines how much force is required to get said object moving. And g is not the "force of gravity," but rather, the acceleration due to gravity. A roller coaster rider at 4 g's does indeed experience a force equal to four times his weight, but it's his "apparent weight" that increases during acceleration, not his "actual" weight.

Oops. That sound you hear is the unmistakable "thud" of me crash-landing to earth. Seriously, color me embarrassed by the gaffe. One of the hardest things about writing on physics for the general public is deciding how much to simplify the intricate details. Physicists always seem to want to include too much information, and thereby lose the interest of their intended audience far too soon. I'm good at holding a reader's attention, but sometimes -- as in the present case -- I play a little too fast and loose with the details, particularly when it comes to how physicists vs. the public use specific terminology. Who ya gonna please, when you can't please both? That's the eternal question

Now, Jen-Luc Piquant is a bit proud and hates to have her shortcomings so baldly exposed; she believes there is a special place in hell for nitpickers like this -- perhaps even Dante's dreaded Ninth Circle. But I've said before that I have no problem being corrected, so long as the people are nice about it, and Z. was as polite as they come; he even emailed back with a correction to his correction. I think folks like Z. should all volunteer as fact checkers at publishing houses, newspapers and magazines, where they can fully indulge their need to make corrections in the work of others, and thereby serve a useful purpose to society by ensuring such mistakes don't see print. Because I happen to agree with Z's statement: "Though physics terms like force, work, power, etc. may have loose meanings in everyday language, they have very precise definitions in physics." I actually take these distinctions quite seriously, and worked very hard to verify accuracy before the book was published. Despite my best efforts, tiny errors crept in, as they inevitably do; it's an inescapable reality of publishing.

Alas, there's not much I can do about it for the moment. Online stories can be corrected almost immediately. Newspapers and magazines can print corrections and retractions. Books are much more permanent. Unless there's a second edition (which is distinct from second or even third print runs), the errors must stay in place, for now. But I do have a blog, and in the interests of accuracy, let the record show that I hereby make the correction.

It's rather fitting that gravity proved to be my downfall, considering my affinity for the legend of Icarus. It might be weak compared to the other fundamental forces, but gravity is an inescapable reality of our human existence. Scientists have to come up with all kinds of ingenious ways to work around the limitations it imposes. Take the "Prometheus Project," a research team made up entirely of undergraduate students who will be exploring how sound waves might be used to extinguish fires in low-gravity environments like the space station. They've already managed to repeatedly extinguish small flames in a controlled laboratory environment using sound, but it's not clearly exactly why it works. The working hypothesis is that sound causes pressure to drop at the site of the flame, which might also involve a drop in temperature at said site, (chilling the flame) or a decrease in the concentration of oxygen (starving the flame).

In what will no doubt be the highlight of their young lives so far, the students get to test their hypothesis this summer aboard NASA's "Weightless Wonder" C-9 aircraft, a.k.a. the "Vomit Comet" -- a moniker that really bugs NASA officials, so I feel compelled to repeat it here, just to yank their chain. (Jen-Luc Piquant is seething with jealousy, since NASA rejected her proposal to study the effects of microgravity on the cellulite of aging celebrities as a possible alternative to liposuction. The anonymous peer reviewer opined that celebrities already defy gravity.) An earlier KC-135 aircraft, retired in 2000, was used to film many of the zero gravity scenes in the blockbuster film, Apollo 13.  The current Weightless Wonder produces 25 seconds or so of weightlessness by flying in a roller-coaster-like path of steep climbs and free falls. (Roller coasters again -- behold the tenuous connection!) Except in this case, the coaster is about 10,000 feet high. The aircraft's dramatic, parabolic flight patterns temporarily counteract earth's gravity, creating "weightlessness," and sometimes leading to motion sickness -- hence the "vomit comet" nickname.

Cool factor aside, the students do have a scientifically valid reason for performing their experiment in such an anti-gravity environment. Conventional fire extinguishers, it turns out, don't work properly aboard spacecraft; the foam tends to spread out in a low-g environment rather than smother the flames. It might be a good idea to figure out how best to extinguish fires in space. Although there are more terrestrial potential applications, too: the knowledge might be useful for fighting fires in computer rooms, where expensive hardware can be damaged by normal chemical extinguishers.

This past February, NASA's microgravity school program also benefited teachers from two southern California schools. One project was called the Rotational Artificial Gravity Experiment, designed to help students determine how fast a space station would have to rotate to create artificial gravity on board. The other was the Bubble Project, aimed at achieving a better understanding of how soap bubbles behave in a microgravity environment: specifically, how long it lasts, its size and its direction of travel in reduced gravity.

It just so happens that the study of bubbles and foam is pretty cutting-edge science, and the Bubble Project isn't the only research venture that seeks to study foam's properties in the absence of gravity. In that infamous, riddled-with-nitpicky-errors book of mine, there's a chapter on foam and bubbles, in which I discuss the work of Boston University researcher Glynn Holt. (It's based in part on an article on the physics of foam I wrote for Discover back in 2002.) It's actually rather difficult for sudsy scientists to create predictive models of foam's rheology -- that is, how it deforms and flows over time -- because anything you use as a container inevitably changes its shape and behavior. Holt got around this problem by using sound waves to float individual drops of foam in mid air using a technique called acoustic levitation. He can even manipulate the suspended drop by altering the acoustic field, changing its position, or squeezing it to cause the bubbles that make up the drop to vibrate.

Sometimes it can seem as if gravity "disappears," even on earth, as with the notorious "Gravity Hill, part of a remote local road located in south central Pennsylvania. For no cost whatsoever, the low-budget tourist can marvel as water seems to flow the wrong way, and cars seem to roll uphill. It's just an optical illusion but it's fun, nonetheless. The news that University of Oregon researchers have made water "climb stairs" in the laboratory isn't an illusion -- but it's a damned clever trick, basically exploiting the same phenomenon that causes water droplets to bead up and dart around a really hot frying pan. The Oregon researchers just turned the frying pan into a very hot ratcheted staircase. (You can see a helpful diagram of the experiment here.)

For most of us, though, there are no clever tricks or illusions to offset gravity. Still, I take comfort in the fact that all the sturm und drang is by its very nature transitory. The NPR link is no longer the top emailed story on the site; it's disappeared into the archives altogether. And after peaking at #14 on Amazon Sunday evening, my book has begun a slow, prolonged descent back into the online reader's abyss from whence it sprang. See? No matter how high you soar, gravity always wins out in the end and brings you crashing down to earth. Icarus learned this the hard way and paid for his error with his life. I escaped with a few scratches to my ego, having learned some very useful things about the finer points of gravity and acceleration in the process. I think that's a fair trade.

After all, one shouldn't let one's fear of flying keep one from strapping on a metaphorical pair of wings and testing the limits -- just to see if it can be done. Far worse than having the odd error in my book, would have been not writing it at all because I was too afraid of making mistakes. So I applaud those students and teachers who brave the Vomit Comet for their daring. It's only by pushing the limits that any kind of growth or progress can be made. Why bother with a life half lived?