Cocktail Party Physics

connecting the dots

Celebrity tabloids and similar gossip rags are filled with unnamed sources -- you know, "Sources close to [Insert favorite Celebrity (TM) here] report that...." I've always wondered who these loose-lipped people are: a source standing close to the Celebrity (TM) on line at Starbucks, perhaps? A casual diner at the next table in a stylin' Hollywood eatery? Or maybe a disgruntled former employee, or pathetic former hanger-on who's bitter because s/he didn't become the Celebrity's (TM) new BFF? Because anyone who was truly close to a Celebrity (TM), wouldn't maintain that position for very long by talking to unscrupulous tabloid reporters, now, would they?

Tabloids aside, we generally expect the average news story to cite its sources by name, with rare exceptions, like when Woodward and Bernstein broke the Watergate scandal. So imagine my surprise when I noticed this little news item on CNET a couple of days ago about a start-up company called Stion with the stated mission of developing thin-film solar cells, mentioning unnamed "sources" in the third graph down. They've received a whopping $15 million in venture capital, which means their technological approach must be pretty promising, but Stion's manager of business development was rather coy about what, exactly, that material might be. He had plenty to say about what it was not -- not silicon based, not cadmium telluride, and not a copper-indium-gallium-selenide compound, either -- but otherwise kept mum, promising to reveal all "in due time," i.e., around 2010, when the first products are likely to be announced.

Sheesh, what a media tease! Clearly, the frustrated CNET reporter, Michael Kanelios, had no choice save to turn to his own Deep Throat, or two. Which, BTW, is not a criticism: he did a commendable job (far better than the celebrity tabloids) of assembling various pieces of circumstantial evidence in favor of the new material being... (drum roll, please)... quantum dots! I'm not sure his evidence is solid enough to warrant announcing this in the headline ("Harnessing quantum dots for solar panels") without a question mark, unless his unnamed sources are very reliable indeed. But it is a matter of public record that Stion's Chief Technology Officer, Howard Lee, worked as a solar researcher (specifically using quantum dots) at Lawrence Livermore National Lab for several years, and accumulated numerous patents relating to quantum dots during his stint at another start-up called Ultradot. And Stion's CEO, Chet Farris, is a former president of Shell Solar. Hmmm. The plot thickens. Kanelios, for one, can connect the dots.

No doubt some of you are wondering what the heck these quantum dot thingies are, and why they're such a big fat deal. It just so happens that I wrote about quantum dots way back in 2003 for The Industrial Physicist magazine -- the closing of which I still mourn, because I got to cover so many cool cutting-edge topics as a contributing editor there. (I wasn't always about the pop culture physics; I used to work for the Dark Side, i.e., Very Serious Science Journalism, or VSSJ.) Quantum dots are essentially tiny bits of semiconductors -- sometimes called nanocrystals, which just doesn't carry the same panache -- just a few nanometers in diameter. It's like taking a wafer of silicon and cutting it in half over and over again (a semiconducting Zeno's Paradox?) until you have just one tiny piece with about a hundred to a thousand atoms. That's a quantum dot. (I think. It's not like you can actually see one with the naked eye. Billions of them could fit on the head of a pin.)

Size matters when it comes to semiconductors: smaller is usually better. Because they're so tiny, quantum dots have some unusual materials properties -- specifically, the all-important electrical and optical ones -- thanks to the quantum effects that kick in at smaller size scales, so they are of enormous interest to researchers. It's interesting physics fundamentally, and it offers an impressive sampling of potentially lucrative practical applications. Trust me, quantum dots are hot, even if they're currently simmering on the back burner in the news-hook-oriented media.

I must confess to finding it easier to write about applications of physics rather than the basic science. But when I started covering the quantum dots area, I learned some useful things about the "electrons and holes" effect that is critical not just to quantum dots, but also lasers and other semiconductor physics. This is not an easy thing for a lay person to visualize, although physicists toss those terms around like high school slang. So here's my attempt at the 411 on electrons and holes (scientific commenters, feel free to add your own take on the subject):

It helps to place semiconductors in general in the appropriate context, i.e., right smack between insulators and conductors. Insulator atoms hoard their electrons greedily, like misers or overprotective parents, and rarely part with them, while conductor atoms are like spendthrifts or exceedingly permissive parents, letting their electrons run amok all over the place (and a good thing, too, otherwise we'd never enjoy the benefits of electrical current). Semiconductor atoms are juuuust riiiight. They don't fling their electrons around all willy-nilly, but neither do they hang onto to them too tightly. It takes a bit of an energy boost to knock an electron loose in a semiconductor, and when the electron breaks free, it leaves behind a "hole" in the atom's electronic structure -- a vacancy, if you will, that another electron, sooner or later, will come along to fill. So a photon strikes a semiconductor atom and creates an electron-hole pair, which physicists call an exciton -- because we need more confusing technical jargon in physics, don't we? Anyway, this enables the electrons to flow as a current. And current = power.

Much of the excitement over quantum dots stems from a decades-long quest to make silicon emit light efficiently in the visible spectrum. Back in 1990, European researchers managed to get porous silicon to emit red light, and figured it came about because of "quantum confinement" relating to the dot's small size. Basically, at 10 nanometers or less, the electrons and holes are being squeezed into such small dimensions that this alters the electronic and optical properties; it's the critical feature of most nanoscale materials, frankly. (Special bonus for Physics-Philes: a 2003 paper in Nature reported that shape might matter as much as size when it comes to quantum confinement.) Things snowballed from there, with scientists making more silicon dots (and, later, germanium dots) that emitted light in lots of bright, pretty colors, especially the highly desirable green and blue ranges. Basically, the bigger the dot, the redder the light, and the emitted light becomes shorter and shorter in wavelength -- and higher in energy -- as the dots shrink in size. This is called "tunability" because you can pretty much tailor the dots to emit whatever frequency of visible light you happen to need for a given application, simply by altering the size of the dots. Believe me, high-tech industries go nuts for anything with tunability. Plus, colors = pretty! Check out the pic! Doesn't it make you want to buy some quantum dots?

The most obvious application is using quantum dots as an alternative to the organic dyes used to tag reactive agents in fluorescence-based biosensors. You know, the dyes start to glow when, say, a harmful toxin is present. But the number of colors available using organic dyes is limited, and they tend to degrade rapidly. Quantum dots offer a broader spectrum of colors and show very little degradation over time. Having all those colors also means you can make light-emitting diodes (LEDs) from quantum dots, precisely tuned in the blue or green range. You can also build quantum dot LEDs that emit white light for laptop computers or interior lighting in cars. As for electronics, the possibilities are endless: all-optical switches and logic gates, for instance, with a millionfold increase in speed and lower power requirements, or, further in the future, quantum dots could be used to make teensy transistors for nanoelectronics.

But the current news is about quantum dots and their potential application to solar cells. As I mentioned earlier, Stion's CTO, Lee, did a lot of work in this area during his stint at Livermore, as have many other researchers. (A more technical overview of this research area by Science News' Peter Weiss can be found here, for those who are interested.)  As the CNET story reports, "Most solar cells on the market today extract electricity from sunlight with silicon and are integrated into glass substrates, which is relatively heavy." A company called First Solar uses a similar structure, but replaces the silicon with cadmium telluride, which is cheaper. As for the CIGS (copper, indium, gallium and selenide) version of the technology, there's several companies working on that, although products have yet to hit the market. It's expected that CIGS solar cells will be cheaper than silicon ones, but not quite as efficient: we're talking mid- to low teens, percentage wise, compared to 22% efficiency (and sometimes as much as 29%) for silicon solar cells. (A fossil fuel like gasoline can show 30-40% efficiency, so even silicon solar cells need to show some improvement in this area for broad practical application.)

So what can quantum dots bring to the solar cell table? The CNET article doesn't go into much detail:

"Partly because of their small size, quantum dots can be highly sensitive to physical phenomena and can be used to trap electrons. Since solar panels work by wiggling electrons out of sunlight and transferring them to a wire, quantum dots in theory could work well in solar panels."

This doesn't really say anything meaningful, to a non-scientist, about the actual process that's taking place -- because the process is very complicated and hard to explain in a short news article. Those electron-hole pairs known as excitons I mentioned earlier? Usually, photons from sunlight that strike the semiconductor material used in solar cells unleash only one electron. In theory, they should be able to loosen more than one, thereby giving rise to several excitons, but for reasons relating to heat loss in atomic collisions, or some such thing (paging Chad Orzel for a better explanation!), there's usually only a 1-to1 ratio. That's why solar cells are limited in their energy efficiency. But last year, researchers working with quantum dots made of lead selenide found they could produce as many as seven excitons (electron-hole pairs) from a single high-energy photon of sunlight. This could boost solar cell efficiencies to as much as 42% -- enough to be competitive with the more common fossil fuel energy sources.

So Stion is doing good work, and with any luck, they'll be rewarded with some healthy profit margins in due time. But all this hard-core quantum physics talk has made me long for the comparable simplicity of the celebrity tabloids. Intellectual stimulation is all very well and good, but sometimes my brain just needs a break. And the latest unscrupulous unnamed sources are telling me there's trouble in some Celebrity's (TM) fairytale paradise...

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.

conversations with dead people

Did you know it's possible to subject your blog to a handy ratings system? We  were thrilled when we found out, and promptly submitted our humble blog for "review." Alas, it came back with a rating of... NC-17! Say what? Sure, we offer alcoholic drink recipes, but Jen-Luc Piquant swears she assiduously checks the IDs of any thirsty freeloading avatars that swing by to sample those libations. And we keep the cursing to a minimum. So why the NC-17 rating?

Well, in recent posts, there were six mentions of "corpse," five mentions of "death," three mentions of "hurt," two mentions of "hell" and one mention of "penis" (a dessicated, detached penis belonging to an ancient Egyptian mummy, but apparently that doesn't matter to the blogospheric ratings board). I leave it to my readers to draw their own conclusions regarding what this says about my psyche. It's all the more embarrassing because Cosmic Variance -- where Future Spouse hangs his blogging hat -- came in with a G rating. Disney meets David Lynch in our Los Angeles abode. Even more galling: PZ Myers at Pharyngula merited a PG rating (2 mentions of "abortion" and 1 mention of "screwing"). C'mon! The guy routinely posts graphic cephalod porn! That's gotta be worth an X rating, or at the very least, an R! At least the marvelous folks at the Shakesville blog  -- from whence I found the rating system -- also garnered an NC-17 rating.

The ratings board was accurate about one thing: we can't deny that we do have a rather morbid fascination with corpses, death, and various other gross-out factors. (I'm currently reading a novelization of the infamous Crippen murder -- you know, the guy who killed his wife, chopped her up, and buried the pieces in the basement. The head was never found.) And we're suckers for a gripping ghost story. Which is why I pounced on a May 14 story in Infoworld about "the ghost who sabotaged the mainframe." When I say "pounced," I mean, clipped and saved in my fodder file until I found an excuse to mention it. But better late than never.

It tells the sad tale of Ernie who, back in 1971, was head of data processing for unnamed nonprofit in New York City. Ernie had recently retired, having spent years setting up the department and writing all the programs for the mainframe. A week after retiring, he was killed in a car crash. And soon after that, all kinds of mysterious strange things started happening around the office. Nobody took much notice, until the door the computer room began opening and closing on its own. Even weirder, instead of the usual cold blast of air that met the workers when they opened the door, there was a warm gentle breeze. And then, the new director of data processing tried to replace the old mainframe computer. The Ghost of Ernie was having none of it, and the new system was beset with problems -- until the new director took a stand and got forceful, demanding that Ernie leave things alone. Apparently it worked, and once the new system was up and running, the old mainframe was sold as scrap. From then on the Ghost of Ernie was sensed no more.

There were some mocking comments around the Internets when this story first appeared, and even its author, Jill Terry, admits she used to be such a skeptic, before she found herself actually arguing with a perceived ghost, and realized that "lunacy is relative." And she's not alone: a 2005 Gallup poll found that more than a third of Americans believe that houses can be haunted, with 32% specifically professing to believe in ghosts. I'm firmly in the skeptic camp myself, but I'm disinclined to add to the ridicule, for reasons which shall soon become clear. Terry's story has some classic tropes of the genre: the warm gentle breeze, the prickling of the skin, the strange occurrences, and odd sounds. All that's missing is a visual: Ernie, apparently, was a shy sort of specter.

The notion of ghosts has been around for millennia, even making an appearance in the Babylonian epic Gilgamesh. We're still fascinated by the subject today. Witness the popularity of TV shows like Medium, Jennifer Love Hewitt's Ghost Whisperer, or cable TV's documentary-style Ghost Hunters. It's all part of man's strong desire for some sort of "life" after physical death, because it's so difficult for us to imagine the prospect of simply "not being."

For all the public fascination, no respectable scientist ever took this stuff seriously -- at least not in public -- until the late 19th century, when a renowned  Harvard professor of psychiatry, William James, joined with a small group of other illustrious scientists to found the American Society for Psychical Research -- the US counterpart to the British Society for Psychical Research. Together, they sought solid, scientific proof of supposedly "inexplicable" phenomena: ESP, mediums (slate writing, table rapping, etc.), and ghostly visitations, specifically, "crisis apparitions": in which a loved one appears to a person at night, and said person finds out soon after that the loved one has died.

James and his cohorts form the basis for Pulitzer-Prize-winning journalist Deborah Blum's latest book, Ghost Hunters: William James and the Search for Scientific Proof of Life After Death. It's a meticulously researched, engagingly written, and fascinating read, championing the courage of James and Co. in defying the scientific establishment by undertaking such a pursuit, without turning a blind eye to their failures and tortured humanity. The history is filled with colorful personalities and both amusing and moving anecdotes, and I highly recommend the book to anyone interested in this unusual period of scientific history. In case you're worried that Blum's book is some New Age-y defense of crass spiritualism: yes, the vast majority of the cases the SPR studied turned out to be fraudulent -- sometimes ingeniously so -- and this was understandably very disheartening to the researchers. But a tiny fraction -- 5% -- defied all attempts at scientific explanation, and gave them the will to go on. (Blum takes no strong stance on that remaining 5%, other than to say it warrants further research until (a) a scientific explanation is found, or (b) definitive proof that they are genuine evidence of an afterlife can be offered.)

I was surprised to learn that Michael Faraday was one of the outspoken skeptics, publishing a letter to The Times of London in 1853 explaining the "secret" behind table tilting, based on his own carefully designed experiment. "The experiment showed that table tilters were often unaware of their own actions," Blum writes. "As Faraday explained, the board was responding to unconscious muscular twitches, 'mere mechanical pressure exerted inadvertently by the turner.'" On the other side of the fence was Faraday's fellow physicist William Crookes, who was an SPR member, off and on, although Blum reports that the objectivity of his research suffered on account of his susceptibility to the more attractive female mediums he studied. Still, the man was hardly a scientific crackpot, even if he wasn't in a par with Faraday's gigantic stature.

The various SPR members - both US and British -- passed on to the Other Side without ever definitively proving any real psychic powers, the existence of ghosts, or the existence of an afterlife. Blum herself largely remains a skeptic, although she admits to being fascinated by the crisis apparition phenomenon. She also mourns the loss of an era when some of the Western world's best scientific minds were brought to bear on the problem. Because that 5% of unexplained events remains just that: unexplained.

That doesn't mean there aren't a few theories. There are still a handful of skeptics seeking more than the usual debunking and unmasking of fraud. They seek a valid scientific explanation for such apparitions, other than the obvious: people can hallucinate or mistake reflections, shadows and strange noises for ghostly activity. Richard Wiseman of the University of Hertfordshire is one of them. He's collected anecdotes and measured a wide range of physical conditions at purported "haunted" sites -- light, humidity, sound, and magnetic fields -- and has reported some interesting findings.

For instance, some haunted locations have magnetic fields that are stronger than normal. It's possible that the stronger fields affect the brain in some way. It's already known that electrical stimulation of the angular gyrus will make you feel as if someone is behind you, mimicking your movements (although if you'd grown up with my older brother, that wouldn't have been a hallucination). A similar kind of stimulation might contribute to near-death experiences. Then there's temperature: people routinely report cold spots or sudden drops of temperature in specific areas, which they believe indicate a ghostly presence. More often than not, it's a draft coming from somewhere in the house, or the result of lower humidity. One of the sites Wiseman studied, Mary King's Close, showed lower humidity in those areas purported to be haunted.

The Close is a series of allegedly haunted streets and houses in Edinburgh. Wiseman's study of the area was carried out in 2005, part of an Einstein Year program sponsored by the National Endowment for Science, Technology, and the Arts. About 70% of the 200 members of the public who participated reported experiencing unusual phenomena, mostly mild (suddenly feeling cold, eg), although some felt they were being watched or touched, felt their clothes being tugged, or heard unexplained footsteps. The results indicate that these experiences are "real" in the sense that people actually feel those sensations. That doesn't mean they're attributable to ghosts. Wiseman was very clear on this point: "Although some people may view the results as evidence for ghosts, our findings suggest that participants' expectations, combined with subtle differences in the appearance and physical characteristics of the locations, may affect how anxious people feel when they enter the spaces, and this may create unusual sensations."

The biggest culprit when it comes to ghostly sounds and sightings might be infrasound, low-frequency sound waves below the range of human hearing, that can nevertheless have tangible effects: feelings of nervousness, for example, or hyperventilation, or even a sense of another presence in the room. There's even speculation that these sound waves vibrate at the resonant frequency of the human eyeball, causing visual hallucinations.

Vic Tandy was a strong proponent of the infrasonic theory, and even pegged the specific guilty frequency -- 18.9 Hz -- before his untimely death in 2005. Officially, he was affiliated with the school of international studies and law at Coventry University, but he was also the unofficial "chief ghost buster." (Perhaps Bill Murray will play him in the film version of his quest.) He wrote two papers for the journal of the Society of Psychical Research: one citing infrasound as the cause of a "haunting" in a laboratory in Warwick, and another citing infrasound as the source of a "ghost" in the cellar at Coventry Cathedral. Lots of otherwise sane people felt uneasy descending into the cellar, sensing some kind of presence, and occasionally -- as in the case of a visiting journalist -- seeing the face of a woman peering over their shoulder.

As for the Warwick laboratory, Tandy himself worked there, and could personally attest that the effects of infrasound feel very real indeed. He was working late one night, and suddenly felt the hairs rise on the back of his neck. At the same time, he caught a glimpse of a gray apparition out of the corner of his eye, that disappeared when returned to face it. The culprit? A newly installed extractor fan. "When we finally switched it off, it was as if a huge weight was lifted," he told the Guardian in July 2000, and he suspected there may also be a connection between infrasound and "sick-building syndrome." I have a strong suspicion that Ernie the Ghost's spooky effects were at least partly due to something like infrasonic vibrations from that old mainframe -- because when Terry and her colleagues got rid of it, the "ghostly presence" disappeared. Regardless, Tandy died before he could complete his investigation into why some people are affected by infrasound and others, apparently, aren't.

On the whole, unless one is seeking to debunk ghoulies and ghosties and psychic powers, engaging in this type of thing won't exactly win the respect of one's scientific peers. Just ask Robert G. Jahn. For 30 years, Jahn ran the Princeton Engineering Anomalies Research lab (PEAR), which conducted highly controversial research on telekinesis and the ability of study participants to influence machines using just the power of thought (unaided any of those newfangled wireless implants that enable monkeys to move computer cursors with their thoughts). The experiments were essentially mechanized coin flips: people tried to influence the outcome of each "toss".

Ultimately, Jahn published more than 60 papers, mostly with the Society for Scientific Exploration, which devotes itself to research topics outside the mainstream, of the scientific community. His "evidence" wasn't exactly compelling: after accounting for statistical fluctuations, he concluded that only 2 or 3 out of 10,000 "flips" could be attributed to influence from the participants' thoughts. After three decades of research, I, for one, would require something a bit more tangible as evidence. Still, science is ideally about rigorous honest inquiry, and there shouldn't be taboos on what's allowed to be investigated -- if someone wants to look into kooky phenomena like ghosts and ESP, and they're adopting a scientific approach, why should they be subjected to ridicule and isolation? It's not like our tax dollars were paying for PEAR's research (it would never have passed peer review, anyway); Jahn relied on private donations.

That quest is now over for Jahn: PEAR closed its doors earlier this year, putting an end to a strange era in Princeton's history. The ever-irascible Bob Park -- author of Voodoo Science -- called PEAR "an embarrassment to science," but I'm more inclined to share the view of Princeton physics professor Will Happer (and I suspect Blum would, too): "I don't believe in anything Bob is doing, but I support his right to do it."

just don't quote me

There's a fascinating discussion over at Tara's place regarding scientists and their frequent reluctance to answer interview requests from the media. I commented on this already on Aetiology, but the issue is multi-faceted enough that I think it warrants some reworking and expansion into a separate post. After all, getting scientists and journalists to talk about their respective differences, and the frustrations that sometimes arise because of them, is an important first step in perhaps fostering a better working relationship between the two groups. Because frankly, we need each other, whether we care to admit that or not.

Tara's main points about why scientists frequently don't respond promptly to requests for interviews are very well taken. I'm well aware of how busy researchers are, how frequently they travel, and how crazed their schedules can get while on the road, especially when one figures in erratic email access. That's why I'm so damn grateful when they take the time to sit down with me, like East Carolina University physicist George Bissinger did recently at the ASA meeting in Salt Lake City. (He chatted for almost a full hour, in the midst of an action-packed day, and gave me the crux of my story in the process. Thanks, George! I shall strive to be worthy of your generosity.) Scientists get a LOT of emails -- perhaps even more than journalists. I've seen it firsthand with Future Spouse, who feels a genuine sense of accomplishment when he winnows his unanswered emails down to a mere 60 or so, even though it takes valuable time away from his research to do so. I'm sure some of the people still waiting for a reply occasionally feel like they're trying to interact with dark matter or something. (Trust me, the dark matter NEVER returns phone calls or emails. We only have indirect evidence that it even exists.)

Still, Tara says she prefers to be contacted by email, and I suspect most scientists would concur. That's certainly my first avenue of attack, so to speak, when seeking interviews, and it's also my preference when it comes to other people contacting me. But then, I mainly write books and magazine articles, which have substantially longer lead times than, say, a daily newspaper or TV news. Some journalists simply don't have the luxury of sending an exploratory email and waiting patiently for a couple of weeks until a scientist has time to respond, then figuring out a mutually good time to schedule a telephone interview. Under the gun of a tight deadline, cold-calling might be the only realistic approach. It's certainly not the ideal one.

Things get a bit sticky later on in Tara's post, particularly when it comes to scientists' fear of being disastrously misquoted or misrepresented in an article. Now, this is a very real concern. It happens all the friggin' time, and not just with scientists. Every one of us who has engaged in any kind of media exposure has a horror story or two to tell.

For instance, Future Spouse and I were among those featured in a Valentine's Day article in the New York Times, about couples who met during business conferences (in our case, the 2006 APS April meeting in Dallas). The reporter -- a highly respected professional, and published author -- did his due diligence, and contacted me prior to publication for some minor fact-checking. I clarified a few factual errors. In writing. But the reporter was traveling at the time, and the editor(s) in charge were, apparently, less diligent. Almost none of the corrections were made -- or were made incorrectly, even though they had the correct information right in front of them. In writing! There's absolutely no excuse for that, other than "Oops! Our bad!"

In another article for a different publication, the assigned reporter produced a "profile" of me so far removed from my actual personality that even my closest friends admitted that, had they not known it was about me, they never would have recognized me. My quotes were totally mangled, usually harmlessly, although in one case,  it was misconstrued to convey almost the exact opposite of what I'd actually said. So I speak from the heart when I assure all you scientists: I've been there, and I feel your pain. The difference is, I consider this kind of experience the equivalent of war stories, to be ruefully shared over cocktails or coffee with colleagues in solidarity, whereas  according to Tara, scientists have a very real fear that their professional image will be irrevocably tarnished by such an experience:

"We spend a lot of time crafting our own articles describing our work, adding the requisite disclaimers, alternative explanations, etc., but all that can be undone by a misleading article (or even a misleading headline, which may be no fault of the reporter).... [E]ach new interview is a gamble, so while it has the potential to bring our work to a larger audience, it also has the potential to mischaracterize our work, or piss off a colleague who disagrees with our interpretation of the data."

This, I think, gets to the crux of the matter when it comes to the longstanding tension between scientists and journalists. It's a multi-faceted issue, and feelings tend to run high, so it's not surprising that this is the aspect of Tara's post that generated the most heated debate. Honestly, I don't quite get it. It strikes me as a contradiction: on the one hand, scientists loathe mainstream journalism because reporters never get anything right, and yet they're afraid a random article will carry sufficient credibility to damage their careers? It makes no logical sense. Newspapers are not peer-reviewed journals; they should not -- and in my opinion do not -- carry as much weight as a scientific paper published in a refereed journal, which should be the only kind of publication that matters when one's research is being critiqued by one's peers. Unless one's peers are looking for ammo to make cheap shots for political or personal reasons -- in which case, they'll find it regardless of whatever article appears. That's bad scientific manners, not a direct result of bad journalism.

The scientists' comments at Aetiology are quite telling: frustration, and often anger and outrage, at the media's stubborn refusal to behave like a peer-reviewed journal and allow scientists more control over the information being disseminated.  Many helpful suggestions were made to minimize the chances of being misquoted: only responding to emailed questions, so one's responses are in writing, for example, or insisting on being allowed to review one's quotes before publication. (One guy apparently tapes his end of the conversation and compares the final quotes with his own taped record. Now that's obsessive.) Dave Mosher had the best suggestion:

"As a science journalist, I can tell you the best thing to do, as an academic getting interviewed and wanted to guide the interview somewhat, is to have analogies cocked, locked and loaded.... [R]eporters go nuts for pre-thought-out analogies/explanations because it's quotable material, and could in fact be the center of the article.... So cranking them out before you speak with someone is a great way to maintain some control of what reporters quote you on."

But the harsh truth is, no strategy is 100% effective, and misquoting and misrepresentation will still occasionally occur. (And no, it wasn't better in "the good ol' days." Take a gander at archives from daily newspapers from the 1920s, or 19th century England, if you don't believe me.) Science communication will always be a double-edged sword in that respect: you trade increased exposure for your research, and fostering a link with the general public through the media, for absolute control over the information that's disseminated. Period. So, um, get over it already.

One particularly angry commenter was Drugmonkey, who wrote:

"So the answer to a journalist is "stop lying." Stop thinking that constructing an article to make whatever point you want based on totally misrepresenting quotes is ok. Start trying to communicate the *truth* of what people say to you, you know, report what happened rather than what you wish happened because it "made a better story." Then maybe scientists will return your call."

Clearly, Drugmonkey has been hurt, badly hurt I tell you, by someone in the mean, nasty media. Let's get a bit more perspective, shall we? It's the rare (and very bad) reporter who deliberately sets out to "lie" in an article. However, it is that reporter's job to shape an article into a strong narrative; that's just good science communication, good story-telling, good writing. It should be based on actual fact, but "truth"? That's a bit more elusive. What Drugmonkey considers the "truth" might be different from what another scientist, or what the journalist, feels is the "truth." Even the most objective scientific data is open to different interpretations, and a big part of any journalistic endeavor is to present more than one side to the story -- the "balance" scientists seem to hate so much. Yeah, yeah, I know this really backfires in extreme cases like Intelligent Design and global warming, but most of the time the model works pretty well. At least the journalist has the benefit of having interviewed several people to obtain a broader view of the matter.

He or she might not always succeed in nailing a story to the satisfaction of all the scientists quoted therein, but a good journalist will always try to go that extra mile to ensure a reasonable degree of accuracy. That said, every reporter occasionally cleans up, or massages, quotes. People don't always speak as clearly as they write, and even with written replies, the journalistic format rarely allows for as much context or details as the average scientist desires. Those column inches are precious real estate and every word has to count. Plus, at any moment before hitting the presses, an article can be hacked even further to make room for the all-important advertising revenue. One commenter rather huffily insisted, "Scientists do know what it is like to write something for publication," but said commenter fails to appreciate the substantial difference between a scientific paper or journal article, and the average newspaper story. It's apples and oranges (although they are both fruit).

Policies vary from publication to publication on letting scientists review articles or individual quotes prior to publication. The Industrial Physicist, for which I wrote for 10 years before it shuttered, always extended this courtesy  -- as a courtesy, mind you, not as a right -- but Discover, Salon, and just about any other mainstream media outlet specifically forbid a reporter from doing so. It really is about journalistic integrity. Believe me, politicians would LOVE to be able to review articles or quotes before they appear in print, the better to spin their carefully cultivated public images. Why should scientists get special treatment? Because they can be trusted to be "objective"? I think not. Scientists are human beings, and they have the same vanities, petty jealousies, and less-than-admirable motives as the rest of the human race, which interferes with their best intentions about as often as occurs in the population at large. It's part of our system of checks and balances that the free press remains just that: free.

In short, the scientific community in general needs to be a bit more sophisticated about its attitude towards journalism -- starting with gaining a clearer idea of how journalism actually works, and what its primarily objectives are (hint: they are not the same objectives as science). It is not, and never shall be, just like publishing in scientific journals. And there's nothing wrong with that. It is what it is.

As for Tara's frank assessment that there's no "reward" for scientists -- especially young scientists -- to participate in interviews for the press, well, I understand her reluctance, to some extent. There's definitely a negative perception of scientists who participate in public outreach and are quoted frequently in the media -- and more than a little snide commentary behind their backs. (Sniffs Jen-Luc Piquant, "Jealous much?") I can only appeal to your altruism. So I'll just say this: Scientists decry the sad state of science literacy in this country, they complain that much of the "real" science being done is never reported, and they bewail the fact that newspapers are killing off science sections right and left. (I join them in the wailing and gnashing of teeth on that score, and raise them the odd rending of the garment.) But they don't want to return reporters' phone calls because it might tarnish their academic image? Again, it makes no logical sense.

If you don't want to consent to interviews, that's your prerogative. I, for one, am sympathetic to all the reasons Tara and her commenters discussed on her recent blog post. But on the flip side, you then forfeit your right to complain about poor science coverage -- because (as I've said before in a prior post) you are a big part of the problem.

running hot and cold

A few years ago, in 2004, a Ben and Jerry's ice cream store in New York City celebrated Earth Day with an unveiling of a prototype "thermoacoustic chiller": basically, a freezer that kept the pints of Cherry Garcia and Chunky Monkey nicely chilled on a warm sunny day by using sound waves, instead of vapor compression of harmful chemicals like hydrofluorocarbons (HFCs) -- the mechanism behind the modern refrigerator. The prototype "chiller" was developed by Matt Poese and Steve Garrett, both physicists at Penn State University.

The underlying effect  has been known for over 100 years, after glass blowers in the 19th century observed that tones were being generated by hot glass bulbs attached to a cool tube. Anything that combines thermodynamics with acoustics is A-OK in my book. It's essentially the same basic concept as a standard heat engine, which derives energy from differences in temperature (ref. Sadi Carnot and Maxwell's Demon). I like to think of it as being the temperature equivalent of dropping a ball from a given height. The ball gains more potential energy the higher it is raised, which converts into kinetic energy when the ball is dropped. The higher the ball, the more potential energy is stored, and the more kinetic energy you get when you drop it. Applied to the heat engine, this means that the greater the difference in temperature, the more potential energy there is to convert into kinetic energy. Maybe it's not a perfect analogy, but it works for me.

Of course, unless you can harness that energy to do something useful, it's largely wasted effort. The Penn State scientists figured out how to do that. The concept derives from the fact that sound waves travel by compressing and expanding the gas (air) in which they are generated. This mechanical energy can be used to cool and heat stacks metal plates in the path of the sound wave. Some get hotter, some get colder, and the result is that critical temperature difference that gives rise to usable energy. Put a couple of heat exchangers on that sucker, and you've got a nifty little cooling chamber. Time magazine declared it one of "The Most Amazing Innovations of 2004." Even better: the gas used is helium, much safer than HFCs. We don't see a lot of thermoacoustic refrigerators on the market just yet because their energy efficiency isn't competitive with the conventional technology. But give it time: scientists are ingenious sorts, and they're making improvements all the time. Thermoacoustic refrigeration is already being used to cool biological samples on board the Space Shuttle.

Poese and Garrett aren't alone. There are lots of research groups working on various fundamental and applied approaches to exploiting this unusual effect -- groups like Orest Symko's at the University of Utah. Symko has a long-standing interest in building tiny versions of thermoacoustic refrigerators for cooling electronics. (Considering how hot my MacBook Pro tends to run, such a breakthrough would be very welcome in the industry.) A couple of years ago, he expanded that program to include all kinds of thermodynamics devices that convert heat into sound, and sound into electricity, for a broad range of possible applications. He and five of his graduate students were on hand at the ASA meeting in Salt lake City to present their latest achievements.

Heat is basically wasted energy, but Symko's devices harness heat that would normally be wasted -- like that emitted by the dual core microprocessor in my MacBook Pro -- and convert it into usable electricity. It's the same basic structure as the thermoacoustic chiller: a small cylinder (the "resonator") that fits in the palm of your hand, containing a stack of metal plates, placed between a cold heat exchanger, and a hot heat exchanger. Take a blowtorch to one end, and air begins to move down the tube, creating sound waves, similar to how a flute produces tones. Also inside the tube is a piezoelectric crystal, a "smart material" that responds to an increase in pressure by producing an electric spark. (Those old cigarette lighters in cars -- since replaced by auxiliary plug-ins -- used piezoelectric crystals.) The tube's dimensions determine the frequency of the sound, in the present case, in the audible range; very small ones could produce ultrasound waves.

Voila! Heat turns into sound turns into electricity. It's not a lot of energy, mind you: Symko estimates that only about 10-25% of the heat is converted into sound, and a little more is lost in the conversion of the sound into electricity, although that's a much more efficient conversion: generally, 80-90% of the sound is converted. Still, you won't see these things being used to power Microsoft's corporate headquarters any time soon. But as an alternative to solar cells in small niche applications, Symko's thermoacoustic devices could be ideal.

There's always a net loss any time you convert one type of energy into another -- that's the basis of the second law of thermodynamics, namely, entropy, a.k.a., The Ultimate Killjoy. It might be a losing battle, but that doesn't mean it's not worth fighting. Someone who wasn't, to my knowledge, in Salt lake City, but perhaps should have been, was Australian scientist Luke Zoontjens, who made news in 2005 with his work on using the sound waves produced from heat derived from car exhaust gases to run car air conditioners. Then a PhD student at the University of Adelaide, Zoontjens sought to exploit the same kinds of thermoacoustic devices, urning heat into sound, and sound into cold air, just like Penn State's thermoacoustic chiller. 

You wanna talk about inefficiency? The average gas engine in a car only gets a 30% return in usable energy on the gas it burns; 70% is released as wasted energy, mostly heat. It says something about the extent of the energy problem, and our society, that this is considered an acceptable loss. Zoontjens' scheme converts the heat from a car's exhaust pipe into sound waves, which are amplified inside the tube to as much as 180 decibels. That energy can then be harnessed to cool the car's interior.  We're looking at a mere 20% efficiency once everything's been converted, but considering it all comes from what would otherwise be wasted energy, technically, it's a tiny net gain.

Most of us never really stop to think about how powerful sound really is. For instance, we take ultrasound imaging for granted, and because it's so safe, many people might not realize that ultrasound at higher frequencies can burn -- which is why it can be used to cauterize bleeding, particularly in vital organs that have hundreds of tiny blood vessels. It "cooks" the proteins in the blood just like the whites of eggs. I wrote about therapeutic uses of ultrasound several years ago for the (sadly) now defunct magazine, The Industrial Physicist. One of my sources, Larry Crum of the University of Washington, pointed out that the late Princess Diana (back in the news yet again, thanks to a new tell-all biography from publishing doyenne Tina Brown) died from uncontrolled bleeding from all those tiny vessels in the vital organs; had handheld therapeutic ultrasound devices been available at the time of her fatal car crash, the princess might have survived.

Sound is also capable of producing extremely high temperatures through the phenomenon of sonoluminescence, possibly even on a par with nuclear fusion. That was the premise of the 1996 film Chain Reaction, in which Keanu Reeves was implausibly cast as a PhD physicist. (Jen-Luc Piquant notes that donning a white coat and glasses really can't overcome the actor's trademark stoned surfer dude demeanor, any more than it could turn a smokin' hot chica like Elisabeth Shue into a mousy wallflower scientist in The Saint.)

Keanu and his co-star, Rachel Weisz, play physicists who have discovered  how to exploit sonoluminescence to achieve "bubble fusion," except instead of a Nobel Prize nomination, Keanu gets framed for the murder of his boss. Oh, and his experiment has been rigged up like an atomic bomb, so he's not only got to clear his name, he has to save the world, too.  Just a typical week in the life of the average research physicist, Future Spouse assures me. (Jen-Luc concurs. When she's not trying to diffuse a bubble fusion bomb and foil an international conspiracy, she's struggling to stabilize extra dimensions of spacetime. C'est la vie!)

It might sound like a load of Hollywood hooey, but sonoluminescence is a very real phenomenon -- "the emission of short bursts of light from imploding bubbles in a liquid when excited by sound," per Wikipedia. It was first observed in the 1930s by scientists working on sonar. (There's some debate over who and when, but I'll go with the more detailed story, because it makes for livelier copy.) H. Frenzel and H. Schultes -- neither of whom bore any resemblance to Keanu Reeves (or Rachel Weisz) -- were trying to speed up the photographic development process by placing an ultrasound transducer into a tank of developing fluid. Instead, it caused tiny dots to develop on the film. The fluid had bubbles, you see, and those bubbles were emitting tiny flashes of light whenever the ultrasound was turned on. Since film is photosensitive -- designed to react to light -- the dots appeared on the developed film.

This came as quite a surprise to scientists, but there was one creature who rolled its eyes in disdain over how thick-headed these humans could be sometimes: the lowly pistol shrimp, a.k.a., the snapping shrimp. This species of shrimp has a set of asymmetrical claws, and the larger one produces a loud snapping sound -- loud enough that the pistol shrimp vies with the sperm whale and beluga whale for the title of "loudest animal in the sea." That snapping sound gives rise in turn to a shock wave powerful enough to stun or kill the shrimp's prey (small fish). Such a shock wave also creates bubbles that collapse and produce a flash of light. Granted, it's of a very low intensity, and usually not visible to the naked eye, but still -- the pistol shrimp species would like us to tell you that "shrimpoluminescence" really should have been noticed much sooner than October 2001. If anyone deserves a Nobel Prize for the discovery of sonoluminescence, it's the shrimp.

Frenzel and Schultes discovered what is now known as multi-bubble sonoluminescence (MBSL). They weren't able to do much detailed analysis, because there were far too many bubbles, and those bubbles weren't around long enough (only a few hundred picoseconds) to make detailed measurements or observations. It took over 50 years before scientists were able to produce single bubble sonoluminescence (SBSL) -- coincidentally, that honor belongs to the aforementioned Dr. Crum, and his collaborator, Felipe Gaitan.

Perhaps the shrimp have a valid point about us lagging way behind on the initial discovery, but scientists have made some impressive advances on the sonoluminescent front since Crum and Gaitan's pioneering work on SBSL in 1989. They can make a single bubble expand and collapse over and over again periodically, emitting that telltale flash of light each time it collapses.

With SBSL, it was easier to analyze this complicated process by focusing on a single bubble, which is how scientists learned that the temperature inside the bubble was hot enough to melt steel. Theorists predicted that it could get even hotter, perhaps above 1 million Kelvins. This was exciting because it meant that it might be possible to use sonoluminescence to achieve thermonuclear fusion. (Take that, pistol shrimp, thinkin' you're all that and a bag of chips, just because you have big, loud snappy claws!)

And this is where the controversial topic of bubble fusion -- a.k.a. sonofusion -- comes in. It's possible in principle, per the work of UCLA's Seth Putterman, although he has yet to successfully demonstrate sonofusion in the lab. Someone who claims to have done so is Rusi Taleyarkhan of Oak Ridge National Lab -- a claim that has sparked a heated debate and even raised allegations of scientific misconduct. The so-called "string wars" might dominate the mainstream media coverage, but there's been just as much finger-pointing, name-calling, and snarky put-downs in sonofusion -- and I'd argue it's an equally sexy topic. (Nota bene: this is not -- repeat, not -- cold fusion, even though the apparatus operates at room temperature. The nuclear reactions -- assuming that's what they are -- occur at the very high temperatures inside the core of the imploding bubbles, which shock wave simulations indicate could be as high as 10 megakelvins,)

The chronological chain of events is a bit confusing, given the amount of back and forth that's gone on, and the fact that all the Wikipedia entries on the subject are marked as being "disputed." So I hope people will feel free to post corrections and clarifications in the comments section. But from what I've been able to gather, Taleyarkhan et al. published a paper in Science in 2002 claiming that the results from their experiments on acoustic cavitation were consistent with fusion (most notably, the amount of neutrons released, and tritium produced from the "reactions").

The trouble began when ORNL colleagues repeated the experiments and announced that their neutron and tritium production was more in line with random coincidence. Taleyarkhan's team published a rebuttal, and followed up with published papers with new claims of bubble fusion in 2004 and in 2005, the latter appearing in the peer-reviewed journal Physical Review Letters. But the number of skeptics grew. Among the most vocal was UCLA's Brian Naranjo, who openly questioned the validity of the Purdue results in a 2006 article in Nature.

Part of the problem is that even Taleyarkhan admits that the reaction doesn't always work correctly, and they are still investigating what the critical experimental parameters might be for achieving sonofusion. His claims were extraordinary, and therefore elicited more scientific doubt than usual. Things got really nasty when allegations of misconduct emerged -- namely, that Taleyarkhan had attempted to actively thwart the efforts of several university colleagues to test his claims -- and a special review committee at Purdue was appointed to investigate the matter.

The story ends fairly positively for Taleyarkhan and his collaborators. Earlier this year, Purdue rejected the allegations of research misconduct, stating that "the evidence does not support the allegations" and concluding that "vigorous, open debate of the scientific merits of this new technology is the most appropriate focus going forward." In other words, fight it out in the pages of peer-reviewed journals, people, and leave university administrators out of it.

So the jury is still out on whether these sonofusion research results are valid, i.e., reproducible. Putterman, for one, has not been able to duplicate Taleyarkhan's experiments. Apparently, the BBC documentary series Horizons commissioned Putterman's reproduced experiment -- how cool is that? I dream of a day when CNN, for instance, sponsors such an experiment to resolve a scientific dispute. Ultimately it all comes back down to energy sources, and given global warming, the price of gasoline, and the myriad of other problems associated with how we power our daily lives, it definitely qualifies as being of broad public interest. At least it should.

stir of echoes

Ace Ventura, Jim Carrey's eccentrically zany pet detective, loves animals of all kinds, with one exception: bats. His distaste was a major source of humor in Ace Ventura: When Nature Calls, the sequel to the original smash hit, because the plot centered on a stolen sacred albino bat in Africa. True, on one level, bats are pretty much winged rodents, but from an evolutionary standpoint, they're fascinating creatures. Perhaps that's why many cultures ascribe to them a special symbolism. In Tonga and West Africa, the bat is indeed sacred, believed to be a physical manifestation of the soul. For the Chinese, bats represent longevity and happiness, and are considered lucky by the Polish, Arabs, and the inhabitants of Macedonia. Some Native American tribes deem the bat a bit of a trickster spirit. In American culture, we have the whole vampires-into-bats motifs, courtesy of the Dracula legends, not to mention certain tormented superheroes who have been known to adopt the costume of a bat for their nocturnal crime-fighting activities.

But Ace isn't alone in finding bats just a little bit icky, too. For one thing, there's that old wives' tale about bats getting entangled in people's hair. Chances are, if this happens to you, it's more likely there's an insect -- like a moth, mosquito, or gnat -- somewhere near the vicinity of your head (if not caught in your actual hair). Bats eat them, and they tend to hunt "on the wing" (i.e., mid-flight). While bats aren't completely blind, they do rely primarily on echolocation (sonar) to hunt for their prey: usually the aforementioned insects. That diving behavior is indicative of hunting for food, and is simply misinterpreted by more squeamish sorts as a personal attack.

I personally find the creatures fascinating; I used to visit the "bat cave" at the National Zoo in Washington, DC, on a regular basis in the summers, just to watch the fruit bats hang upside down, flit about, and occasionally emit those eerie high-pitched cries as they navigated their environment. So I was sorry to have missed an especially nifty paper at the Salt Lake City acoustics conference on something called "jamming avoidance" in big brown bats. Fortunately, Greg Edelman of the Naval Research Laboratory was at the session, and gave me the highlights during a break between sessions the next day. (The best part of scientific conferences is the informal chats after talks, wherein I get to pick peoples' brains.)

The big brown bat is an actual species (Eptescius fuscus), not just a description of the animal. And apparently it really is possible to "jam" the frequency of a bat's ultrasonic signal. There was a time when scientists believed that tiger moths practiced a form of jamming to protect themselves from hungry bats, although the current accepted thinking is that the moths produce ultrasonic signal to warn bats that they are "chemically protected" -- an attribute Wikipedia terms aposematism. (The concept reminds Jen-Luc Piquant of an anime film called Ninja Scroll, in which a female character was poisonous to the touch -- a highly effective defense mechanism against things like rape, but also a curse, in that she and the man she loved could never consummate their relationship.)

Different species of bat use echolocation in slightly different ways. We all know that bats hunt and navigate by emitting ultrasonic pulses and using the returning echoes to determine the location, speed and distance of nearby objects or prey. This is called active echolocation. And several insects have evolved "bat sensitive ears" as a counter-measure, including the possibility of frequency jamming, which would disorient a bat. The big brown bat (BBB, for short) has what seems to be a unique strategy for protecting itself against jamming, according to James Simmons of Brown University.

BBBs emit "frequency modulated (FM)" signals ranging from 50 to 23 kHz. But Simmons has found that when trying to detect targets in a fairly wide band of noise (or out in the open), they tend to lengthen their sounds in such a way that the frequency modulation tapers off into what is almost a constant frequency segment. The result is that rather than having the signal's energy dispersed over the bat's full range, it is focused down to a much narrower range -- between 24 and 28 kHz -- which means more energy to the signal. You can hear the phase call of the big brown bat on the prowl for food here; graphically, it's represented at left, below. 

And there's more! Simmons performed a series of experiments in which he tried "jamming" specific frequencies, beginning with the BBB's preferred narrowed range. He found that the bats responded by shifting their emitted frequencies up or down to  avoid the jammed frequency.  Apparently they prefer higher frequencies, but when Simmons jammed the top of their range, he found the bats shifted down to lower frequencies to compensate when necessary. It's a bit like what sometimes happens when I use that little FM transmitter device to play my iPod in the shiny new Prius. Occasionally, the chosen frequency experiences interference from an actual radio broadcast. That is, the iPod signal is jammed. I respond by switching to a different frequency that is not experiencing interference.

There's a lot of questions that remain unanswered, most notably, why does the BBB do this frequency shifting in the first place? Okay, perhaps to counteract any signal jamming ability its prey might have evolved, although the evidence for that is contested. And is there a physiological mechanism at work here that we might be able to emulate? Because apart from the biological and neurological interest, Simmons has a real-world application in mind: naval submarines use sonar for navigation, and are vulnerable to the same kind of jamming. If scientists can figure out precisely how bats manage to do this, they might find improved countermeasures for that kind of sonar interference.

Another species of gleaning bat -- called the pallid bat (Antrozous pallidus) -- uses active echolocation for navigation, but employs a passive approach for hunting, to better elude detection by its prey. Basically, it listens for noise generated by insects, and thus has both external and internal "ears" -- what amounts to two parallel auditory systems. A recent paper on the topic appeared in the Journal of Comparative Neurology.

The passive approach might have evolved in response to its prey's sensitivity to ultrasound -- itself probably an evolved ability to evade hungry bats. For instance, David Yager of the University of Maryland has studied the interactions of bats (predator) and praying mantises (prey). Yager made his name in the field while still a graduate student at Cornell University, when he discovered the praying mantis has a single ear located in the center of its chest, that is highly sensitive to ultrasound in the frequency ranges commonly used by bats.

Researchers had assumed that the ultrasound disoriented the insect, since it tended to respond by swirling and diving erratically in flight. But Yager found that those movements were a defense mechanism, not a vulnerability. When a bat locks onto a target, it begins emitting its pulses very rapidly, a kind of climactic "feeding buzz." It makes sense: in order to get the most precise information possible about its prey's speed, distance and location, the bat needs as much feedback as possible, so it sends out many more pulses. The mantis senses the "feeding buzz," realizes it's been locked on as a target, and performs a series of evasive maneuvers similar to what jet pilots would execute to evade an incoming missile. A species of moth, Noctuidae, employs a similar defensive strategy. They're also equipped with a special hearing organ sensitive to bat sonar; the muscle twitches in response to the ultrasonic pulses, and the moth embarks on a series of evasive aerial maneuvers, just like the praying mantis.

There's always a danger of misinterpretation when studying living creatures. (Edelman mentioned a famous experiment by B.F. Skinner concerning the behavior of pigeons; I wasn't familiar with the story, but Skinner apparently got things very wrong.) It's not like the bats can help clarify their behavior by answering probing questions. So I don't quite know what to make of another paper at the ASA meeting by Robert Dooling (University of Maryland) -- which has already been featured on Science Daily and mentioned by Afarensis, with more coverage no doubt to come -- on what frequency ranges dinosaurs could hear.  I mean, we have a hard enough time figuring out why bats and insects do the things they do; how much more difficult is it to decipher the behavior of creatures long extinct?

But that's exactly what Dooling and his cohorts are attempting to do, starting with the knowledge that the inner ears of birds, crocodiles and dinosaurs are very similar in structure, most notably when it comes to a part called the basilar membrane. They found a correlation between body mass of a species and the size of that membrane. Smaller, lighter creatures, like birds, can hear higher frequencies that larger, heavier species, like elephants or dinosaurs.

Based on their analysis, Dooling's team concluded that dinosaurs probably heard things in the lower range of the frequency spectrum, extending, at most, to about 3 kHz (equivalent to a conventional telephone). They probably couldn't hear higher frequencies, such as the high-pitched sounds of birds. Which is ironic, since current paleontological theory holds that today's birds are probably the closest living relatives of the extinct dinosaurs. And all this time, the frustrated birds were convinced the dinosaurs were just ignoring them. It's also good news for any Young Earth Creationists who believe man and dinosaurs existed at the same time. Human voices fall around 8 kHz (although we can hear up to about 20 kHz). Sometimes it's a good thing not to be heard.

[UPDATE: An eagle-eyed commenter rightly says "Gotcha!" The 8 kHz refers to overtones in the human voice; the actual frequency range is much broader, and part of it would indeed fall within the range og what the researchers think dinosaurs may have been able to hear. And that's bad news for the YECs. I'd advise them to speak in high-pitched falsetto... you know, just in case.]