Cocktail Party Physics

physics enters the octagon

[NOTE: This post originally appeared at our new home at Scientific American.]

One of the biggest movies of the fall so far is Contagion, which garnered strong reviews -- including from the science blogosphere -- and roared to a $23.1 million opening when it debuted a few weeks ago, easily beating out the other box office contenders. So it's understandable that a few hidden gems slipped under the radar. Case in point: many people missed the sleeper film, Warrior, whose cast of characters includes Brendan Conlon (Joel Edgerton), a.k.a., the Most Badass Physics Teacher E-VAH!

When we first meet Brendan, he doesn't look too tough: his two young daughters are gleefully painting his face during a family birthday party. But he's definitely hands-on in the classroom, instructing his students on the finer points of F=ma by means of a sledgehammer and concrete blocks. And then we see him lifting weights in the garage, and learn he moonlights as a bouncer at a local strip club to help make ends meet, since his salary as a public school teacher isn't sufficient to ward off the looming threat of foreclosure on their modest Pittsburgh house.

At least that's what he tells his wife Tess (House MD's Jennifer Morrison). In reality, he has re-entered the world of amateur mixed martial arts (MMA) to earn a bit of extra cash. A former UFC fighter, he makes quick enough work of the local "weekend warriors" with delusions of being the next Matt Hughes or Randy Couture. No doubt that physics background helps, too: martial arts is all about force, energy transfer, leverage, and momentum. (Perhaps the official motto should be, "Physics can kick your ass!") But when the school board learns of his extracurricular activities, he is suspended without pay for the semester.

Principal: "We can't have one of our teachers cage-fighting in a strip club!"

Brendan: "Technically, it was in the parking lot outside the strip club...."

What's an out of work physics teacher gonna do to save his house and protect his family? He's gonna enter Sparta, the biggest, most brutal MMA competition out there, with a winner-takes-all purse of $5 million. That means coming out of retirement to take on a field of younger, powerful, highly skilled fighters like the undefeated Koba (played by real-life MMA fighter Kurt Angle). And it also pits him against another underdog, Marine Corps war hero Tommy Riordon (Tom Hardy) -- who just happens to be Brendan's estranged brother. I think we can all see where this is going, and if not, the trailer lays it all out for you:

Don't let the lackluster marketing campaign fool you: Warrior isn't just another tired retread of Rocky, despite the working-class background and underdog status of its heroes. For starters, most such films allocate a few days to film climactic fight scenes. But Warrior is so fight-intensive that director Gavin O'Connor spent an entire month filming those sequences. The pacing, cinematography, and realistic choreography of those scenes is astonishing -- it captures the beauty, not just the brutality, of this controversial sport (which, for the record, is nothing like professional wrestling, despite the cheesy trappings and scantily clad ring girls).

Those sequences took their toll on the actors, too. In an interview with Den of Geek, Edgerton revealed that he and co-star Brady trained "literally from seven in the morning until three in the afternoon. It was fighting all morning, eat a massive meal with the stunt guys and then come back to lift massive weights... Because at some point Tom and I knew we had to get our shirts off, stand in a cage... and look like we belonged there."

The film is also grittier, more thoughtful, and starts slow out of the gate, carefully building up the characters and complex, layered relationships, so that by the time the two brothers face off in the Octagon for the inevitable showdown, we understand fully what's at stake, and we're rooting for both of them. It's not a prize purse, or a thirst for macho glory. Each brother is literally fighting for his life, and for the lives of those who depend on him. You desperately want them both to win -- but there can be only one victor. Them's the rules.

So who will it be, the brute or the tactician? In one corner, you've got the pitbull ferocity and merciless efficiency of Tommy, a seething cauldron of pain and rage, who once tore the door off a tank in Iraq to save a fellow Marine, and who dispatches most of his opponents in the first round with a vicious knockout punch. (Announcer #1, musing on Tommy's chances before his first fight: "I dunno, sure, he's tough, but a tank doesn't hit back." Announcer #2: "Yeah, but.... HE TORE THE DOOR OFF A FRICKIN' TANK!".)

In the other corner, there's the steely, calm resolve of Brendan, the high school physics teacher with the big, big heart, who doesn't exactly dazzle with his technical prowess, and seems to lack the killer instinct. (Announcer #1: "Remember him from the UFC?" Announcer #2: "Yeah, I remember how unmemorable he was." He then compares Brandon to a harmless goldfish in a plastic bag.) But he's smart, and patient, and unbelievably tough. He can take a helluva beating and wait for an opening, a small mistake, that he can exploit to gain the upper hand and win -- if he doesn't get killed in the process.

Who wins? Go see the movie! Warrior deserves a bigger audience than it's managed to find so far -- which is why you should all run right out and see it while it's still in theaters. On your way home afterwards, perhaps you can take a moment to consider the plight of our woefully underpaid physics teachers, forced to engage in brutal cage-fights in the parking lots of strip clubs. Then again, is there anything more suspenseful than a physics class where the teacher might at any moment whip out a big ol' can of whup-ass to demonstrate Newtonian mechanics?

Okay, so Brandon is fictional. I know there are tons of hard-working high school physics teachers out there, laboring in the trenches to reach students who honestly can't see what possible use they could have for physics. I invite readers to nominate their favorite, most inspiring physics teacher in the comments, to be featured in a future blog post -- because they deserve the recognition! Right? And hopefully, one day, a pay raise.  

RELATED BLOG POSTS:

FYI, I earned a black belt in jujitsu in 2000, and have been a fan of MMA since the early days of the UFC, although I don't practice anymore, nor do I follow the sport religiously. But I do write about it from time to time, particularly on the underlying science. Here's some of those prior posts:

"Band of Brothers" (3 Quarks Daily)

"Fighting the Forces"

"It's Just a Flesh Wound"

"Science Hits the Streets"

 

zapping the new age

I really could have used co-blogger Allyson's advice about skeptic etiquette earlier this year. At a recent party, a bunch of my non-science-geek friends and I got to moaning about all the time we spend in front of our computers. I've always thought one of the ironies of my life was that when I was growing up, my parents yelled at me to not sit so close to the TV and I now earn my living . . . sitting too close to what is, essentially, a TV. Lots of us older folks have eye fatigue from it, especially from the old CRT screens that really were pretty much the same as a TV. But one of my fellow partiers loudly declaimed that we were all being irradiated by our computers too, and that she'd bought this special amulet to turn back those rays and all the other irradiation modern life subjects us to and "other negative energies." The best part was that the woman she bought the amulet from is able to recharge it remotely and is always adding new protections to it. Best money she'd ever spent, she said.

 Moments like this just make my brain hurt.

We'd already had the LHC-black hole discussion in which I'd successfully quashed that panic, but my bullshit meter was almost off the dial with this. I had to really bite my tongue not to say something scathingly sarcastic to someone I didn't know, and it was all I could do not to roll my eyes like a Kewpie doll. It was odd (and kind of heartening) how the room went really silent though. And then I was chagrined to realize I didn't really have enough hard data at my fingertips to rebut everything she said, and that was embarrassing. I know about the scientific studies refuting the dangers of overhead high voltage wires, but I only have a vague grasp of how CRTs and LCDs work. So I thought I'd use my ignorance (shameful, I know) to offer up a quick lesson in how to refute this particular species of New Age Quack, diplomacy not included. (Check with Allyson about that.)

Part of the problem is that people get freaked out by the idea of radiation in general, not realizing there are many types of it and that we are, indeed, being irradiated all the time, not just by our electronics. That darn visible light bombards us all the time! The electromagnetic (EM) spectrum is huge and only the higher end, beyond the visible spectrum, is strong enough to be truly dangerous. The harmfulness of radiation depends on its energy, whether it's powerful enough to knock electrons off an atom's orbital shell, turning it into an ion: ionizing radiation.

For example, the wavelength in sunlight that tans you or, in excess, gives you skin cancer is not the visible spectrum or we'd all have fried eyeballs (which is what happens when you look directly at the sun because the light is concentrated through the lens of your eye onto a small spot on your retina, like a bug under a magnifying glass). It's UV or ultraviolet radiation, just next door to the violet end of the visible spectrum (hence the ultra prefix) that makes you sizzle. And that's the least of its effects. Over the long term, UV light can cause cellular and molecular changes that result in cataracts, permanent changes to skin and fibrous tissues, and skin cancer. Because it causes chemical changes in the body, the effects can be exacerbated by "birth control pills, tetracycline, sulphathizole, cyclamates, antidepressants, coal tar distillates found in anti-dandruff shampoos, lime oil, and some cosmetics."

The most common sources for ionizing radiation are nuclear reactions natural and man-made (fusion and fission) and natural radioisotopes. Don't know an isotope from an antelope? An isotope is a version of an element that has a different than usual number of neutrons (a different mass number) but the same chemical properties. A radioisotope emits enough EM energy to strip away the normally tightly bound electrons from an atom, making it a charged particle, like x-rays. Only the shortwave end of the EM spectrum has enough energy to do this—not the electrons coming out of your CRT TV.

While it's true that every appliance in your house that uses an electric current is surrounded by an extremely low frequency (EMF) electrical field, that radiation is of the non-ionizing sort, even the microwave. The health hazards of this type of radiation are probably negligible in the low concentrations we're exposed to.There are some exceptions, of course. Stick your head in the microwave and you'll cook yourself, but that's because microwaves excite the water molecules until they give off heat. You won't be radioactive afterwards, just cooked. Likewise infrared radiation, which  makes some beautiful photographs!). IR filters allow viewers to see differences in ambient temperature, which is why they're used in night scopes, but the radiation itself is not up to much more in everyday concentrations than heating you up a little.

Much like the radiation that's coming off your computer and TV screens. CRTs are not so popular now that flatscreens have gotten cheaper, but the initials stand for Cathode Ray Tube, which is the source of the "ray" part that seems to freak people out. That ray is a stream of electrons produced by the heated cathode filament and steered by electromagnetic coils. Those electrons pass through a fine-mesh mask and strike a screen coated with phosphors, temporarily goosing them into a more excited state, making them glow. So that electron energy beam is mostly absorbed by the phosphors on the screen. Some of it does escape, but it's mostly hanging around the glass screen making it staticky and attracting dust motes. Because the first thing a free electron (not to be confused with a free radical) wants to do is bind to something. It's lonesome, just a little negatively charged particle looking for its love match in the orbital shell of some other atom. If there are enough atoms with odd-numbered electrons around (like copper's 29), they pass the electrons around like a swingers party and you get a current. That's the crackle you hear when the screen turns off, and why you sometimes get zapped when you touch a CRT display. The free electrons find you more attractive than the glass.

So, those pesky free electrons—how harmful are they? Um, depends on the source energy (see comments below). There is a type of radiation that involves free electrons (beta decay), but these are high-energy ionizing particles that come out of of the nuclei of radioactive materials like plutonium, not out of hot filaments in a cathode ray tube (which is essentially like a lightbulb). The truth is, you're exposed to more radiation risk in a routine x-ray or in the radon-choked basement of your house than from a cathode ray tube. That's because not all radiation is alike.

Because radiation exists as both particles and waves, its potential for damage depends on how much energy it has. The higher the frequency, the more energy it has and the more potential for damage. That's because some radiation—radio waves, for instance—either passes harmlessly through you or is reflected off your skin, like some wavelengths of light; they're low energy, long wavelength. High levels of exposure to even low-frequency/low energy waves can have an effect on biological systems, but the that seems mostly negligible at everyday exposure levels. Some EM radiation, like x-rays, pass through the softer tissues of your muscles and organs but are stopped by the denser bones, leaving those blank, unexposed spaces you see on x-ray film that show your skeleton. When x-rays strike the atoms in your tissue, including those in your DNA molecules, they have enough energy to knock the electrons off, creating charged ions that alter the usual chemical reactions in your body, or even break the DNA up. The cells die or work in weird ways. If this happens in enough cells, mutations or other reactions that we read as radiation sickness or cancer can occur. In small doses though, the body is self-correcting enough to heal whatever damage is done in the name of seeing that fracture in your tibia or the denser mass of cancer tumors.

LCDs are an entirely different fish in some ways, but operate similarly. These displays are built in kind of a sandwich style with the liquid crystals in the middle between layers of glass, filters and electrodes that supply the current. The material that gives LCDs their acronym are crystals that have lost some of their positional rigidity. Nematic liquid crystal molecules, which are usually rod-shaped, are still more organized than isotropic crystals, but both are semi-liquid. Application of a current causes them to realign or "untwist" themselves into various configurations that block or reveal the light which also passes through vertically and horizontally aligned polarizing filters. The pixels in this case are a substrate of indium-tin oxide. If you've got a liquid crystal display (LCD) monitor, you may have noticed that it attracts significantly less dust to its display surface than your old CRT. This tells you that there are fewer free electrons floating around looking for other atoms to bind to (or that your house is a lot cleaner than mine is). That's because instead of spraying electrons gatling-gun style, in LCDs the current is channeled in a grid to different parts of the screen in a closed circuit.

Plasma displays have a similar structure to LCDs, but the medium that's excited by the current is, obviously, plasma: charged gas confined in "cells" sandwiched between several layers of glass and other materials. Since plasma displays ultimately use UV radiation to excite their pixel phosphors, they contain a protective layer of magnesium oxide (the same compound found in both Milk of Magnesia—as magnesium hydroxide—and some electrical cables. Versatile stuff!) that blocks the ionizing UV radiation) but is transparent to the visible spectrum. So you're still probably getting zapped less by your plasma TV than by an old CRT, though the CRT "leakage" is the standard by which safe radiation is measured for electronics.

The upshot is that none of the radiation emanating from your appliances is the kind emitted by nuclear materials, so you're not going to get cancer or radiation sickness from it. None of it is of sufficient energy to fry so much as a mosquito, let alone cook your brain. In fact, one thing most people overlook is that we are ourselves walking electrical fields. Our brains are electrochemical dynamos, zipping signals along our synapses millions of times a second, the proverbial telephone switchboard. Our own electrical field created by the movement of current between cells is slight, but the fields inside our cells are as powerful as lightning bolts. One day, we may actually become our own local area network. That little shock of electricity between people that we talk about is not only a metaphor.

Okay, now that you know you're not being bathed in deadly ionizing radiation or high levels of non-ionizing radiation from your computer or TV or microwave, what about that "charging remotely" thing? How's that work? Wifi? Radio waves? Light? Microwaves? Hey, maybe that's frying our brains! Slap a radiation hazard sign on all those psychics' doors! But thanks to Allyson, at least you can be polite about it.

the devil's playground

Jen-Luc Piquant should technically be wearing mouse ears in honor of today's post, but they clash horribly with her stylin' beret. Why? Because on Sunday, we dragged the Spousal Unit to Disneyland for a day of magical adventures! Okay, a day of standing in impossibly long lines for the privilege of experiencing a brief period of euphoria, followed by trudging to a different section of the park and a wait in another impossibly long line. Repeat until done. See, the Spousal Unit had never been to Disneyland, or Disneyworld for that matter, and it's a slice of Americana that really must be experienced firsthand -- although I have a love/hate relationship with the place. It's crowded, cheesy, and all about crass merchandising (motto: all headgear is improved by the addition of mouse ears!), but there's some nugget of goodness at its heart.

Or maybe that's just my childhood nostalgia talking. When I went with my family as a kid, it truly did seem like a magical kingdom. More practically, I have an entire chapter on amusement park calculus in my book-in-progress, and we were looking for interesting problems to add some rigor to all that candy-coated amusement. (Each chapter has a specific curve associated with it -- the "face" of a function, as David Berlinski puts it in A Tour of the Calculus -- and the idea is to have at least one problem for each in an Appendix showing the derivations of the concepts being discussed.) Amusement park physics is all the rage: high school physics teachers have been known to take classes on field trips to Six Flags, for example (except for one rather curmudgeonly school in Canada where the notion proved controversial). Six Flags is great for Newtonian mechanics; it's all about the pulse-pounding extreme rides. Disneyland is as much about artifice and storytelling as it is about adrenalin (and, of course, crass marketing!).

Everyone should go to Disneyland with a physicist at least once, particularly one as good-natured as the Spousal Unit, who let himself be dragged from one long crowded line after another, filled with over-excited youngsters, frazzled parents, and purple-haired, pierced hipsters doing their best to look bored and act like they were Really Just There For the Irony. Visiting Disneyland with a physicist is an entirely different way of looking at things. For instance, first I dragged him to The Twilight Zone's Tower of Terror in the adjacent California Adventure park. The schtick is that this is a cursed hotel in which four people got into an elevator one day, were zapped by lightning and mysteriously disappeared into... The Twilight Zone! Along with their luggage, so at least they had a change of clothes and toiletries after being transported into a nightmare dimension.

The interior is done up in vintage Gloria-Swanson-making-like-Miss-Haversham-in-a-home-gone-to-seed-style, and eventually you find yourself in a mock elevator, strapping yourself into your seat. You'll need that strap, too. We were lifted to the "top floor" of the faux-hotel structure, and then cursorily dropped into simulated freefall. Physics! As one would expect, this lifted us out of our seats slightly, as much as the straps would allow, and we got that one glorious moment of seeming weightlessness, before reaching a jerky stop and being raised back up for another drop. And another. After it was over, the Spousal Unit turned to me and gleefully exclaimed, "We made a parabola!"

Yes. Yes, we did. But until I started writing this book, it would never have occurred to me to think about the ride in this way. Score a point for calculus and hands-on education! Plot out our path point by point on a cartesian grid and connect the dots, and you do indeed get the telltale parabolic curve. The nice thing about the Tower of Terror's freefall, for book problem purposes, is that it forms a complete parabola, since it goes up and down several times. The part where we're falling is technically half the curve.

Years ago, when I still lived in NYC, I went to Six Flags New Jersey with my badass dojo cronies, and we all went on the Devil Dive. Forget simulated freefall, this ride was more akin to bungee jumping. Three of us were strapped into a big harness -- after signing a waiver promising we wouldn't sue Six Flags if we died horribly -- and lifted to the top of a 200-foot tower. That doesn't sound very high unless you're the person hanging precariously from a harness at the top of it -- then it becomes very high indeed. I remember Gabe nervously remarking, "Um, gee, maybe this wasn't such a good idea after all..." Then the signal sounded, they released us and we plummeted, screaming, towards the ground. One half of a parabolic curve, served straight, no chaser!

Even better, just before hitting ground, the harness catches and swings you outward over the park in a sweeping pendulum motion. And you swing back and forth, more slowly with each pass, until you've slowed down sufficiently for the ride operators to grab you and bring you back down to Earth. At least one person in our little party was convinced that having three people in the harness instead of two would result in a faster descent. Au contraire, mon frere! He had forgotten his high school physics class, namely, that objects fall at the same rate regardless of mass. (Granted, that's in a vacuum, and we weren't in a vacuum, but I doubt the extra person made an appreciable difference.) The Devil Dive is like a double dose of Galileo: freefall and the pendulum. It's understandably a hugely popular ride: there are homemade videos all over YouTube, like one:

But I digress: this is supposed to be about Disneyland. How to top the Tower of Terror? The obvious choice was Space Mountain. We braved the 45 minute wait, hopped in our little faux spaceship, and hurtled through the darkness at high speed, thrilling to the hairpin twists and turns we couldn't see coming. The Spousal Unit liked Space Mountain. A lot. As who could not? He didn't think it was a "conventional" roller coaster, in that it relied on pushing and pulling the cars mechanically, rather than simply exploiting gravity. (According to this article, that's not the case: Space Mountain's design does not incorporate cheats like "energy wheels" to keep cars from stalling at the top of hills -- except at the very end of the ride in the re-entry tunnel. Per the author, Bill Watkins, who was the ride's track engineer, "I submit that this does not violate the pure gravity ride principle because we are now down (nearly) at station level and it's important to fine-tune the vehicle speed before it enters the station." Discuss.)

There was no obvious moment of feeling suspended in true freefall, either. There were many sudden shifts in velocity, however, and we contemplated how to turn that observation int some sort of calculus problem involving vectors. Vectors also came into play at the Mad Tea Party. (*belligerence on*) Yeah, we went on a kiddie ride. What of it? Huh? HUH? (*belligerence off*) The teacup ride is actually more complicated, from a physics/calculus standpoint, than it initially appears; it's not just about angular momentum. (If that were all I was interested in, we could have just stuck with the King Arthur Carousel.) We noticed that every now and then, we'd get an especially sharp, fast rotation, whereas at other points, no matter how fast we tried to spin our little teacup, we just couldn't reach the same speed. Physics! See, there is one big circle that rotates. Within that circle are smaller ones that rotate independently. And within each of those circles are the individual "teacups", which rotate independently from the two bigger circles.  

Technically, we're talking here about velocity, not merely speed. Velocity is speed with a direction, traveling along a vector. In the case of the teacup ride, each "circle" moves along its own vector. (That vector is constantly changing its direction, of course, since the "circle" is in rotational motion.) A standard textbook calculus problem would ask students to add together all those vectors at a given point to determine the total velocity. Sometimes the vectors work against each other, pulling in different directions and canceling each other out. That's when the teacup spun more slowly. Other times, the vectors line up in the same direction and add together, and you get those moments of faster rotation. (And you thought there couldn't possibly be calculus in a teacup. Hah!)

Next it was off to Splash Mountain in "Critter Country," in which one steps into a little canoe and floats down a deceptively innocent-looking canal filled with water. (Buoyancy! Every calculus book should mention Archimedes!) There are little animatronic animals along the "banks" of the faux canal, singing an incredibly annoying, jaw-clenching ditty about positive thinking and finding your "laughing place," and having a zip-a-dee-doo-dah day! Honestly, it's enough to make you wish you had a BB gun with which to wipe the smirks off their silly robotic faces. Clearly, the animatrons know what's coming: a sudden drop into the depths of a cavern and SPLASH! The front of the canoe hits the bottom, displaces a large amount of water, and whoever is seated in the front seat gets thoroughly doused. The Spousal Unit promptly regretted his chivalrous offer to take the front seat instead of me.

Oh, but the ride doesn't end there. We experience another sudden drop, and another big splash, and then must endure the shrieking laughter of the animatronic animals, which has gone from annoying to vaguely sinister, particularly in the eerie lighting of the fake cavern. (Is it me, or does that robotic raccoon look like it's ready to gnaw on our sodden bones?) They have found their laughing place, and it's called Casa de Schadenfreude. As a final ignominy, there is one final 50-foot water drop -- you know, because there might be one small piece of clothing not yet thoroughly soaked through.

Actually, Splash Mountain is a lot of fun, and quite refreshing on a very hot day. We were not there on a very hot day, however; it was surprisingly cool for Anaheim. We squished our way back over to New Orleans Square into one of the gift shops to buy replacement clothing. (According to the clerk, this happens all the time when people ride Splash Mountain.) This was the only point in the day where the Spousal Unit showed a hint of pique; sodden jeans are not a pleasant sensation when the sun is about to set.

There's definitely a lot of physics and calculus fodder in Splash Mountain, but the Spousal Unit was understandably focused on his slowly-drying attire. He explained that the rate at which this occurred formed an exponential decay curve -- as does the rate at which a hot cup of coffee cools to equilibrium. Specifically, the coffee initially cools very quickly, but the rate of cooling slows considerably as the coffee approaches equilibrium with its surrounding environment. Ditto for our clothing: the moisture evaporated quickly at first, then the rate slowed down, and down... would we forever be slightly damp? It was starting to look that way.

To kill some time before our dinner reservation, and give our clothes a little extra time to dry, we went to the Haunted Mansion (Pepper's Ghost illusion in action!), Thunder Mountain Railroad (another roller coaster), and the Mark Twain riverboat. Finally, we went on my all-time favorite ride, The Pirates of the Caribbean. Sure, there was water (buoyancy again), and one initial drop, but this time we didn't get wet. Huzzah! And our dinner reservation was at the Blue Bayou -- the only "fine dining" establishment in Disneyland, actually sited just inside the Pirates ride.

It's actually got a rather nice ambience, and good Cajun-inspired food -- served up in enormous Disney-sized portions -- even if they don't serve any alcohol. The Spousal Unit was very much in need of a drink by then, and the Tinkerbell Fruit Punch with the fairy light garnish just wasn't going to cut it. But at least he got the signature dessert -- a boat-shaped "cookie" with an edible sail featuring a piratical skull and crossbones motif:

magnetic moments

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

physics is fundamental

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

deriver's ed

Like many people, I have a few problems with the factual accuracy of The Da Vinci Code, even though I'm much more likely to cut authors some slack when it comes to fiction (so long as they don't make public claims to historical accuracy, as Dan Brown did). But apart from a few overstatements, the depiction of the Golden Ratio (phi) and related mathematical phenomena was reasonably on target. Case in point: the murdered Louvre curator in the beginning of the story leaves behind a coded message for his granddaughter, a sexy French cryptologist named Sophie. It's a string of seemingly random numbers -- 13-3-2-21-1-1-8-5 -- which Sophie unscrambles to reveal the first eight numbers of the Fibonacci Sequence.

You probably already know the drill (c'mon, even if you skipped the book, you at least saw the film, if only to snicker at Tom Hanks' disastrous haircut): after the first two terms, each number is equal to the sum of the two previous numbers, to wit: 1+1=2; 1+2=3; 2+3=5; 3+5=8, and so on, into infinity. But the fun doesn't end there. If you take each number in the sequence and divide it into the one that follows, the answer will be very close to phi -- an irrational number with infinite decimal places, commonly cited in shortened form as 1.618. As you progress through the sequence, dividing one number into the next, the answer will come closer and closer to the value for phi, without ever actually reaching. Try it: 5 divided by 3 is 1.666; 13 divided by 8 is 1.625; 21 divided by 13 is 1.615; and so forth. Plot the Fibonacci Sequence graphically, and you get pretty logorithmic spirals, like this:

I was reminded of the Fibonacci Sequence while ruminating on last week's calculus lectures, expanding on the two central concepts of the derivative and the integral. The key to both lies in breaking something down into the smallest possible increments, an infinite progression of single calculations that nonetheless accumulates and converges towards a single definitive answer. And just like dividing Fibonacci numbers into each other, as those intervals get smaller and smaller, the result gets closer and closer to the actual "answer."

The similarity probably ends there. Both my calculus lectures last week made no mention of the Fibonacci Sequence, and chose instead to once again evoke Zeno and his various paradoxes of motion. To recap the paradox of an arrow flying through the air: if that motion is divided into infinitely smaller and smaller increments of time and distance, in what sense can we say the arrow is "moving" at all? How can a single instant have an actual "speed"? Philosophers can be so tedious sometimes. For all practical purposes, calculus resolves that paradox, and thanks to Michael Starbird's spiffy DVD calculus course, I now have a reasonable grasp of how it does this. (Yay me!)

On the whole, Starbird keeps things reasonably simple. He began with the most basic example. Since the derivative is a measure of change -- how temperature changes, how the Dow Jones average changes, etc. -- the most basic example is motion: change in position with respect to time. So Starbird envisions Zeno driving a car (Jen-Luc points out it should really be a chariot, but we'll grant Starbird some artistic license) along a straight road at a steady unchanging speed, and in the process, running a stop sign. As luck would have it, Officers Newton and Leibniz are on duty  and pull Zeno over. Zeno denies he ran the stop sign. As proof, he presents the officers with a time-stamped still photo taken of the car just before its nose passed the stop sign. How can they prove the car was moving at that point, and not stopped? Too bad he got caught by Newton and Leibniz, the co-inventors of calculus.

Here's where the details start to overwhelm the story arc a little, but they are admittedly necessary. That straight road is divided into intervals at every possible distance, even infinitesimally small ones, and at each point there is a traffic camera that takes a time-stamped still photo of the car as its nose passes that point on the road. This makes it a pretty magical road, but we're good at suspending our disbelief in order to achieve a greater truth. Officers Newton and Leibniz can pull out their own photographic evidence: an infinite number of still shots taken at smaller and smaller intervals along that amazing road. So they can show where Zeno was at the two-minute time, subtract where Zeno was at the one-minute time, and from that determine how far the car traveled: one mile. Divide that by the time it took to travel that distance, and you get the car's average speed: one mile per minute.

It might be possible for Zeno to argue with that one counter-example, but not with an infinite accumulation of evidence. Newton and Leibniz offer similar evidence for ever-smaller intervals (eg, at the 1.1 mark, the 1.01, mark, ad infinitum), performing the same exact calculations each time, and the answer is always the same: 1 mile per minute. Ergo, Zeno's car did have a speed at that instant, and that speed was 1 mile per minute. According to Starbird, the evidence doesn't lie in looking at what the car was doing at that very instant, because Zeno was correct when he said that an object can only be in one place at a single moment. Rather, it lies in the accumulation of evidence taken from every possible increment of time (before and after) the critical mark in question.

Ingenious! Also incredibly tedious. Our hats are off to Newton, Leibniz, and untold mathematicians before and after them who repeated the same exact process of calculation, over and over again, until they'd compiled sufficient "proof" that the derivative formula works. It takes a Special Kind of Person to do that. We are not that special. At least I'm not a smartass like this self-proclaimed mathematical genius. (Jen-Luc Piquant, on the other hand....)

Nonetheless, while Starbird's example works, it's a highly idealized, carefully tailored classroom analogy. In the real world, no driver moves at constant steady speed. So Starbird presents the exact same scenario with one crucial difference: the car is now accelerating. It's still necessary to set a few basic parameters, namely, that at each interval of time, Zeno looks at his watch (or mini-sundial) to record the exact minute as he passes that point, and then must square that number. Plus, he must ensure that he's always at the mileage marker that is the square of the time. For example, if the watch reads 1 minute, the mileage marker will be 1; if the watch reads two minutes, Zeno's car will be at mileage marker 4. And so forth. The general principle is that, at every moment, the car's velocity is exactly two times the time.

Starbird goes into considerable detail, but the basic concept is the same: Zeno's car still has an instantaneous speed, based on an accumulation of evidence showing where the car was at all times before and after the moment in question. The same highly repetitive process applies, running the same calculation outlined above for smaller and smaller intervals of time and distance. But there's a crucial difference: instead of getting the same answer each time -- as in the steady state example -- one gets slightly different answers each time. But as the intervals get shorter and shorter, those answers get closer to a convergence: in this case 2 miles per minute. It's never exactly 2, just like dividing one Fibonacci number into the next never exactly equals phi. But it's a pretty darn close approximation, and easy to draw the inescapable conclusion that the instantaneous speed at the moment in question must be 2 miles per minute.

The integral complicates matters further.  Essentially it's just the flip side of the derivative: with the derivative, we seek to determine the car's speed based on how its position changed over time. The integral seeks to determine how far the car traveled based only on measurements of its speed at given locations along the same magical straight road. In both cases, however, we're still taking an accumulation of information in tiny parts of the problem to construct a whole answer.

Say Zeno has kidnapped a rival philosopher (let's call her Jen-Luc) who was heckling him in the town square when he was trying to pontificate to his followers (and anyone else in a toga who'd listen). Jen-Luc is bound and gagged in the back seat, able to view just the speedometer, but fortunately she has a video camera on hand, trained on said speedometer, to record the exact speed being traveled. (No doubt the Historical Anachronism Society will object, but again, we claim artistic license and opt for willing suspension of disbelief.) After an hour, Zeno unceremoniously drops his prisoner on the side of the road and drives away.  How can Jen-Luc  use the information about her speed recorded on the video camera to figure out how far she went, and hence her location? That way she can call me on her anachronistic Cyber-cell phone and tell me where to pick her up.

Assuming a constant speed of 60 miles per hour, and knowing that one hour exactly has elapsed since her perfunctory kidnapping, it's pretty easy for Jen-Luc to conclude that therefore, she has gone 60 miles. (Along a straight road. That probably leads to nowhere.) But once again this is unrealistic. It's far more likely that the car's speed kept changing. No matter, Jen-Luc is tight with Officers Newton and Leibniz, so she knows she can use the time-stamped images on the videotape to see how fast she was going at particular intervals. The shorter the intervals, the better, because the speed is less likely to vary by much over very tiny times and distances.

How do we take the variation into account? By setting limits around the correct answer to get a workable range for determining distance. It's even more labor-intensive than the derivative. First, we  do a series of calculations based on the slowest (starting) speed at the start of our journey, breaking that journey into smaller and smaller increments to arrive at a close approximation to the total distance traveled. But this will be an underestimation. So we also need to do the exact same labor-intensive process for the fastest speed the car was traveling over our entire one-hour journey. The resulting approximation will be an over-estimate of how far we went, but at least we know that the correct distance is somewhere in between those two values. 

Jen-Luc has the patience of Job (plus, she really wants to come home) and will keep doing this unbelievably repetitive process at smaller and smaller intervals. She will get ever-finer approximations of the likely distance traveled; that is, the range becomes smaller and smaller, converging towards a single answer without ever reaching it exactly -- just like with the derivative. Jen-Luc can't determine her location via any single division of the interval of time; she gets it via an infinite number of increasingly improved approximations. The power of the method is this: as long as she knows both her position and velocity at any given moment in time, she can determine where she was at every other moment in time in her short journey. That's how scientists can make such impressively accurate predictions about classical physical systems.

Clearly we learned a lot last week, although in fairness, these are just the tiniest baby steps in the course; until we get start performing applied calculations, we can't truly be said to be "doing" calculus. But we do have a greater appreciation for the importance of position and velocity in classical mechanics, and why Newtonian laws break down at the subatomic scale. See, even though the calculations are a series of approximations, at some point at the macroscale (things the size of Zeno's car, for example) the intervals become so small that the difference between approximations is really pretty trivial. I can probably locate Jen-Luc if I know she's somewhere between 1/4 inch and 1/2 inch on the side of the straight road to nowhere. But at tiny scales, even tiny differences become pretty darn important. And the Uncertainty Principle tells us that were Zeno's car the size of a subatomic particle, the more accurately we measure its position, the less we know about its velocity, and vice versa. So the Newtonian calculations break down from lack of precise information. Fortunately, others came to Newton and Leibniz's rescue and founded quantum mechanics. (Sure, it's all about probabilities and averaging things out a la Feynman's sum-over paths, but the predictions still work incredibly well.)

Does your head hurt yet? Ours did. After an entire week wrestling with such heady ideas, we were in need of a stiff drink. And apparently we're not the only ones. We learned from fellow physics blogger Ben Schumacher that there is a well-known mnemonic for memorizing the first few digits of another irrational number, pi: "How I want a drink, alcoholic of course, after the heavy lectures involving quantum mechanics." The trick is to count the letters in each word to get 31415926.... Schumacher went one step further in his online research and found some interesting tidbits via Wikipedia. Check out his post (linked above) to read a pi-mnemonic poem that parodies Edgar Allan Poe's "The Raven," extending to 740 places. Truly ingenious.

But we still needed a drink. Fortunately we have a growing collection of physics-themed cocktails at our disposal, plus a few recipes from a recent article in Wired on molecular mixology entitled "Better Drinking Through Chemistry" (see our prior post on the topic here). Lacking a class-IV laser, we can't even attempt caramelaserizing red wine with a vanilla bean. And we are disinclined to special-order cola-flavored Pop Rocks from Japan to make a dehydrated rum and coke. But at some future date we're definitely going to try our hand at a Jellied Gin and Tonic:

1 frozen lime

2 oz simple syrup

1-1/4 tsp citric acid

1/4 tsp bicarbonate of soda

1/4 tsp confectioner's sugar

1-1/2 sheets of sheet gelatin

1 oz gin

2 oz tonic water

Freeze lime and cut into thin chips (even infinitisemally smaller and smaller chips if you want to be all calculus-like about it). Coat slices in syrup and 1 tsp citric acid, then bake at 150 degrees until crisp. Mix bicarbonate of soda, sugar, and remaining citric acid. Soften sheet gelatin in cold water for two minutes. Warm gin and add gelatin. Pour into shallow baking pan lined with plastic wrap, add tonic, and refrigerate for two hours. Cut into 1/2 inch cubes. Put cube onto lime chip, sprinkle on sugar-soda-acid mixture, and serve.

Sure, it's pretty labor-intensive, but once you've made all those little cubes, you can sit back and ponder things like this: In 2004, scientists at the Technische Universitat Wien in Austria actually managed to measure the shortest possible interval of time to date: 100 attoseconds. According to this article at BBC News, stretching 100 attoseconds to the point where it lasts one second, that one second would last 300 million years on the same scale. That's close enough to an infinitesimally small segment of time for me. Even Zeno might be impressed.

science hits the streets

Anyone who's ever been involved in science education and outreach knows firsthand how resistant one's intended target audience can be to any attempts to broaden their knowledge of science. This is especially true of physics, which has a (not entirely undeserved) reputation of being inaccessible and, well, non-user-friendly. There will always be a certain percentage of the population with an innate interest in science, and that percentage keeps science museums, public lectures, and science fairs/competitions in business. But how do you reach the rest of the people, the ones who must be dragged kicking and screaming into anything that smacks of science education?

If you're Brian Schwartz, a physics professor at CUNY Graduate Center in New York City, you don't wait for people to come to you. You take science right into the streets. Schwartz heads up a popular science-and-arts program at CUNY, sponsoring public lectures, demonstrations, musical and theatrical performance pieces, all dealing in some way with topics in science. His latest effort, held just this past weekend, was the Amazing, First Ever, Science Street Fair. CUNY rented several booths in two planned NYC street fairs -- long a beloved mainstay of summer life in the Big Apple -- and invited numerous education and outreach organizations and individuals to man each one, all part of an effort to bring science to the people. On Saturday, the booths could be found on Third Avenue, between 12th and 13th Streets. On Sunday, the event moved a bit further uptown, to Lexington Avenue between 37th and 38th Streets. Just to make sure the event was recorded for posterity, CUNY hired a roving videographer to wander through the street fair, capturing "performers" in the act, as well as the delighted reactions of the crowds.

The New York Hall of Science showed passersby how to make their own green slime, and gave several live demonstrations of a dissection of a cow's eyeball, announcing each gruesome step via microphone. ("And as we peel back the cornea, just like the skin of an onion....") There was a chemist demonstrating why popcorn pops -- offering free popcorn in the bargain -- and a host of science-themed magic tricks by magician Bob Friedhoffer. Representatives of the American Physical Society were on hand as well, doling out free copies of a nifty Color Me Physics coloring book for kids, along with free crayons. (There's a downloadable version of the coloring book here.) Some of the kids started coloring right then and there, which was probably just as well, since the crayons began to melt around mid-afternoon, thanks to the first summer heat wave of the season.

Yours truly was also on hand for this memorable event, not as an observer, but as an active participant. Somehow I cajoled a few members of my jujitsu dojo in Brooklyn to brave the sweltering heat and spend an entire two days with me, demonstrating martial arts moves as a means of elucidating "the physics of the fight." The over-arching theme of the Science Street Fair, announced on all the bright yellow banners, was "Science is fun!" We paraphrased that just a bit: "Science can kick your ass!" It seemed to play well with toughened New Yorkers. And technically, I'd argue it's true.

On hand to showcase their respective martial arts skills were 16-year-old Amanda, a green belt who started training when she was 6 years old; our newest black belt, Dave Campbell (he literally just passed his test two weeks ago); and me. Notice how tiny Amanda is: just a hair over five feet tall, weighing all of 100 pounds. Don't let that sweet face and small stature fool you. The girl can do some serious damage. Taking the picture was my very good friend -- and one of my first instructors -- Jordan Dos Santos, who took the lion's share of the breakfalls over those two days, and never once complained. (Jen-Luc Piquant spent much of that time hanging out in cool air-conditioned coffee shops, only emerging whenever a media opportunity presented itself. She claims excessive heat and humidity is simply ruinous to her  pixelated, purple-hued hair.)

Jujitsu is, to put it mildly, a high-impact martial art; you don't want to take those falls on pavement. So we dragged a bunch of wrestling mats into lower Manhattan and then took turns running through various techniques, stopping occasionally to explain to the gathering crowds some of the physics principles behind what we were doing. It proved to be a memorable and eye-catching way to talk about concepts like center of mass, momentum, energy transfer, leverage, torque, fulcrums, and levers, among other things. And talk about practical applications: using the principles of physics, a smaller person can overcome a much larger attacker. Case in point: here's Amanda tossing Jordan onto the ground, even though he out-weighs her by 100 pounds:

See? I told you she was tough. (Dave emailed me the next day, admitting he'd gone home and popped handfuls of Advil because "Amanda hits really hard!") Thanks to Amanda's inspiring example, we managed to coax a few passersby -- kids, mostly, but a few adults were brave enough to venture forth as well -- onto the mats, to try a few punches and kicks, and learn the fundamentals of a basic hip throw. It proved to be a highlight for at least one kid, who thrilled to the novelty of tossing Jordan over his back, and was heard to utter afterwards (at the APS/Color Me Physics booth), "I almost killed that guy over there!"

Well, no: Jordan is well nigh indestructible, it seems -- a good thing, since the kids just LOVED beating up on him, for some reason. We suspect his neck could be lined with adamantium, just like the X-Men's Wolverine. It's the only way to explain why he can just bounce right back to his feet after taking falls like the two pictured below.

One throw is called irimi nage, and is essentially a "clothesline" technique: it should be familiar to any Steven Seagal fans, since Seagal uses it to great effect in films like Down by Law. It's incredibly easy to execute -- note that I am already done with the throw and able to just stand there watching Jordan hit the ground -- but it's a brutal fall to take.

The second throw (tomoe nage) should be familiar to Star Trek fans, since it was a favorite  of Captain Kirk's. It's a bit trickier to execute, but fortunately, Jordan's center of mass falls somewhere just under his chin. This means he flies quite prettily through the air, with minimal effort on my part, earning him the dojo moniker "Air Jordan" because of his extended "hang time." The throw looks really cool, and  never fails to evoke gasps from onlookers, especially kids.

(Yes, to Jen-Luc's fashion-conscious horror, I am wearing a blue plaid flannel shirt, on a hot summer day. I needed something hardy, with lapels, that could get accidentally ripped without causing me great distress. The flannel shirt was less heavy than the traditional judo gi.)

Thanks in large part to the efforts of CUNY staff, the event got tons of local media coverage, including Channel 11 News and the New York Daily News. CBS News actually covered the street fair live (thereby forcing us all to set up our booths an hour earlier than originally planned, whether we were "morning people" or not). You can see the entire segment here. There's great footage of folks from New Jersey's Liberty Science Center having fun with liquid nitrogen, and of a scientist (David Maiullo of Rutgers University) lying on a bed of nails, even allowing the reporter to stand on top of him at one point. And the CBS camera crew captured the priceless moment when an Albert Einstein lookalike (Latif Rashidzada) perched himself atop a little go-cart powered forward by what looked like a fire extinguisher -- another of Maiullo's creations, designed to demonstrate the Newtonian principle of equal and opposite reactions, in a highly visual fashion.

Our little booth got some CBS air time, too, although the reporter seemed to think we were practicing tae kwon do instead of jujitsu. Still, it was gratifying to hear the shocked gasps of the anchors at the site of Dave slamming Jordan into the mats: "Yow, that must have hurt!" In truth, it doesn't hurt at the moment: breakfalls are designed to dissipate some of the impact energy, and we're trained not to land on, say, fragile joints. But there is a cumulative effect that takes its toll, and both Jordan and I were admittedly feeling the burn after two very long days of intense physical activity. From my perspective, it was well worth the pain and effort, just to see the smiles light up kids' faces as they successfully executed their very first hip throw, and realized physics could help them achieve something that they thought was impossible.

I'm not saying we changed the world in a mere two days, magically transforming every random passerby into an amateur armchair physicist, or every child into a budding young scientist. Let's face it, you're not going to get across much in-depth understanding of even simple Newtonian mechanics when you've got two minutes or less of peoples' attention. The very format of a street fair demo reduces everything to short, pithy sound bites, by necessity. But you can convey the simple message that science (biology and chemistry, as well as physics and astronomy) is part of our everyday lives, and perhaps ignite a desire to learn more. 

Most importantly, you can counter the often negative stereotypes of science, and scientists, that prevail in the public consciousness. As one young boy (who had just thrown Jordan) enthusiastically declared as his parents led him away from our booth: "Science is cool!" Talk about a snappy sound bite....

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?