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"

 

smooth is green

UPS used to run commercials bragging that they kept their planes immaculately clean because a clean plane has less drag and saves energy.  They didn't mention how much energy it takes to produce the water and soap, or to treat the water after it's been used.  Most of us didn't really care all that much, either.  As airplane prices start to rise with the new geopolitical unrest, people are paying more attention and realizing that sometimes, little things can mean a lot.

One of the most difficult basic physics concepts to accept is that no energy is required to keep an object moving at constant speed if there are no forces acting on the object.  Force is required to create acceleration, not velocity.  You must supply a force to throw a ball in the air, but in the absence of any external forces the ball would go on forever in the same direction once it got started.  

The primary reason why this is so difficult for students to accept (and why even very intelligent people like Aristotle got it wrong) is because a person is highly unlikely to encounter a situation in which an object is not subject to friction.  Unless you live in space, every object you encounter is going to be affected by gravity, friction and air resistance.  This remains one of my primary pet peeves about how we teach physics.  Why do we insist on starting out by telling students things that contradict everything they have experienced in life thus far?

Air resistance is the friction created when air molecules bounce off a surface.  While the up/down forces are important for keeping the plane in the air, we are also interested in the force the air molecules exert in the direction opposite to the direction in which the plane is moving.  The sum of the tiny forces exerted by the very large number of molecules that oppose motion is called drag.  Drag is one of those external forces that require the plane to constantly supply energy.  The higher the drag, the more fuel required to keep the plane moving at a constant speed. 

Drag depends on a lot of things, including the density of the air (lower density means fewer molecules encountered during the same time), the cross-sectional area of the plane (a bigger area hits more molecules) and speed (a faster plane hits more molecules in the same time). 

The concept of area is interesting when you're talking about friction because the critical parameter isn't so much the macroscopic area, but some type of surface area that takes into account the surface roughness on a micro- or even nano-scopic sense.

I've discussed this in reference to surfaces, like wood and skin, but it applies to everything:  It may look and feel smooth to the eye, but If you look at any surface closely enough, you will find roughness on some scale.  As you might imagine, a perfectly smooth surface will produce less drag than a rough surface.

Aerodynamics is very important to racecars when engine power is limited.  When going to tracks like Daytona and Talladega, NASCAR teams apply dummy decals to the bare metal of the car's body.  They paint the car, and then remove the decals.  Keeper decals are applied in the relief cavities made by the paint, and then the car is clear coated and sanded smooth.  Even the roughness associated with the raised edge of a decal is large enough to be of concern to a race team.  A small difference in drag can have a big impact in results when races are won and lost by thousandths of a second.

Commercial aviation isn't concerned as much about speed as it is with cost.  According to portfoilio.com, fuel prices usually account for 30 percent of operating costs; however, when oil prices keep rising (as they are doing now with the increased unrest in northern Africa), they can account for 40 percent of the cost of a flight.

I'm suspicious of 'magic numbers' like the $100/barrel mark, but it makes sense that there exists a tipping point for air travel that probably isn't too removed from the $100/barrel mark.  Ticket prices rise with oil prices.  At some point, ticket prices are so high that businesses stop approving travel and leisure travelers stay closer to home.  The airlines cut prices to attract travelers, and end up flying planes that are actually losing them money.   Unless, of course, they find ancillary fees they can tack on for checking bags, drinking soda or reading magazines. 

In December 2010, U.S. airlines used 929 million gallons of fuel at a cost of 2.141 billion dollars.  A 1% decrease in fuel comsumption represents a savings of 21 million dollars in just one month.  When fuel prices rise rapidly, so does industrial interest in technologies that can make even small improvements in efficiency.  Dirt sitting on the surface of the plane makes the surface rougher and increases drag; however, washing is not without cost.  You have to pay for the person power, the water, the tools and the detergent. Wouldn't it be nice if there were a way to Scotchgard against surface roughness?

That's a little harder said than done.  Planes undergo extremes in heat and cold, and if you think the wind on a day with a -20 F wind chill feels like needles on your face, imagine the force a surface must sustain moving at 500 mph at 35,000 feet. Anything applied to the surface of the plane has to be flexible enough to sustain the thermal cycling of the surface as it gets warm and cold, and has to be able to bond to the surface without coming off.

There's an inherent penalty for coatings:  American Airlines applies minimal paint to their planes because paint adds mass.  In space flight, where the cost per pound is even more significant, not painting the external fuel tanks on the space shuttle saves 600 pounds.  An unmanned launch costs more than $10,000 per pound, so even saving a few pounds on a spaceflight represented a major cost advantage.  It's not as significant on airplanes, but the coating's benefit has to offset the monetary and weight cost of applying the coating.  They can't be too expensive to apply, they have to last long enough that they aren't constantly having to take planes out of the fleet to re-apply the coating, and for commercial airlines, they have to be adaptable to the branding and required identification.

Wax was one of the first vehicle coatings that made the surface smoother and shinier.  Wax is applied to the car and forced into the pores and scratches by physically pushing it in, then removing any extra wax.  It's a lot of work, but the thin coating that results from a well-applied waxing repels water, increases shine, and smooths the surface.  Teflon or silicone coatings also have been used - those are normally small particles of the filler that are suspended in a liquid.  The liquid flows onto the surface, the particles are supposed to fill in the indentations, and then the liquid solidifies.  The smoothness of the surface, however, is going to depend on the size of the particles and how effectively you can get them into the nooks and crannies.  As you can see at left, the smaller the particle, the smoother the final surface.  Nanoparticles can get into smaller indentations and there is a lot of effort in developing drag-reducing nanomaterials for everything from yachts to the blades of wind turbines.

EasyJet, a UK aviation company, is testing out a new nanoscale coating for their planes that promises to effectively reduce drag by about 40%.  That reduction is expected to translate to about a 2% savings in fuel consumption.  Although that doesn't seem like much, EasyJet estimates it would save them about 22 million dollars from their annual fuel bill of about 1.2 billion.

The coating is called TripleO protective system, which has the acronym "ooops".  This was not unfortunate, it was intentional, as the princiapl from the company that developed this system owns a chain of auto repair stores.  The material being tested on the British jets uses an unspecified nanotechnology that the company says crosslinks with the paint to form a durable coating.  At less than a tenth the diameter of a human hair thick, the additional mass of the coating is negligible. 

One of the problems with coatings is getting them down into the nooks and crannies so that they form a really strong bond with the surface they are coating.  Delamination or spalling is the term used when a film separates from the surface it is covering.  It's what happens when your nail polish flakes off.  TripleO overcomes the problem of how to get the material down into the cracks by washing the plane first with oxalic acid.  The materials on the company's website note that this creates a positive charge on the surface, so I'm guessing that the acid dissolves a very thin layer of paint, leaving a bunch of atoms desperately looking for something with extra electrons that can offset the positive charge.  The company's polymer-based coating is negatively charged, so the surface actually pulls the emulsion into the crevices.  The coating bonds with the paint to form a smoother surface.  As a bonus, the surface also repels dirt, which reduces how often you have to wash the plane.

EasyJet is running an experiment. They've coated eight planes and will compare the fuel mileage of those planes with the other 192 planes in their fleet.  If the fuel savings are significant relative to the cost of the application and maintenence of the coating, they'll coat the remaining planes. If EasyJet saves save 2% of their fuel costs, that would correspond to 40 million dollars a month if the mainstream U.S. Aviation fleet followed suit.  Possibly more important than how much money the company saves on fuel is that the planes are burning less fuel and thus generating fewer emissions.  It seems like a win-win situation.

TripleO has worked with the auto industry, aviation (including British military planes) and even yacht racing, where drag is a major issue in speed.  If I ran TripleO, I would ship a couple quarts of the product to Charlotte in time enough to get it on a stock car at Talladega in April.  If their claim of decreasing drag by almost 40% is true, I can't see how it isn't a perfect solution: it's lightweight, clear, compatible with paint and it's not illegal.  Yet.

 

if woodpeckers played football

One of my more distinct childhood memories is of visiting my grandmother's house in Lewiston, Maine, a small-ish (back then) town in the southern part of the state. It was a big clapboard house on a quiet street, on the edge of a large wooded area. I wandered aimlessly in those woods one afternoon, pretending to be an explorer of some sort (as children do), until I stumbled onto a clearing and snapped out of my fantasy world, suddenly aware that (1) I had no idea where I was, and (2) it was eerily quiet. Quiet, except for an occasional rapid-fire tap-tap-tap echoing through the clearing from a nearby tree. This was my first real-world encounter with a woodpecker -- most likely of the pileated variety, common to the area -- and I found myself wondering: Doesn't all that pounding away at tree trunks give the woodpecker a headache? Because it looked like it should hurt. A lot.

Kids always ask the best, most basic questions; they haven't learned yet to pretend to be smart, to be ashamed of their ignorance; they're just curious about how the world works. And the best scientists ask those kinds of questions too, which is why we might roll our eyes and chuckle a bit when we read about two California scientists who decided to delve into the underlying science of why it is that woodpeckers don't get headaches. There's more to it than an easy punchline. Ivan R. Schwab of UC-Davis and his late colleague, Philip May of UCLA, won the 2006 Ig Nobel Prize in Ornithology for their work, published in the Journal of Ornithology -- and the Ig Nobels, as founder Marc Abraham would be the first to tell you, are designed to honor research that first makes you laugh, and then makes you think.

See, it's not such a stupid question, especially since, during courtship, the male woodpecker can drum a good 12,000 times a day (normal rate is still an impressive 500-600 times a day, usually to forage for food). And those aren't just light taps, either. A woodpecker typically drums away at a rate of 18-22 times per second, with a "deceleration" force of 1200 g. (Recall from high school physics class that the more slowly you decelerate, the less the impact, because the energy is dissipated over a longer period of time. Sudden stops or sharp blows, therefore, can pack quite a wallop.) Humans, on the other hand, will lose consciousness under 4 to 6 g's. and a sudden deceleration of 100 g will cause a concussion.

And now a new paper just appeared in Bioinspiration and Biomimetics entitled, "A Mechanical Analysis of Woodpecker Drumming and Its Application to Shock-Absorbing Systems," building on Schwab and May's earlier research. Schwab and May's study found that the key to protecting the pileated woodpecker from chronic headaches or more serious concussion had to do with the structure of their heads -- "thick muscles, sponge-like bones, and a third inner eyelid," all of which work together to absorb impact -- and the fact that woodpeckers make straight, clean linear strikes. Per Live Science:

One millisecond before a strike comes across the bill, dense muscles in the neck contract and the bird closes its thick inner eyelid. Some of the force radiates down the neck muscles and protects the skull from a full blow. A compressible bone in the skull offers cushion, too. Meanwhile the bird's closed eyelid shields the eye from any pieces of wood bouncing off the tree and holds the eyeball in place. "The eyelid acts like a seat belt and keeps the eye from literally popping out of the head," Schwab [said]. "Otherwise acceleration would tear the retina."

Okay, that's interesting, you might be thinking, but what good is that insight? That's where UC-Berkeley's Sang-Hee Yoon and Sungmin Park come in. They're the authors of the most recent paper, and they studied videos of woodpeckers in action, and also took CT scans of the bird's head and neck (see image, above) to more clearly determine how it absorbs mechanical shock so well. Specifically, the beak is both hard and elastic, there is an area of spongy shock-absorbing bone in the skull, and woodpeckers have another springy structure in back of the skull called a hyloid. The skull structure works in concert with cerebrospinal fluid to further suppress vibrations.

Yoon and Park then set about finding ways to artificially mimic these attributes in a manmade mechanical shock absorbing system, specifically to protect microelectronics components. Per New Scientist:

To mimic the beak's deformation resistance, they use a cylindrical metal enclosure. The hyoid's ability to distribute the mechanical loads is mimicked by a layer of rubber within that cylinder, and the skull/cerebrospinal fluid by an aluminum layer. The spongy bone's vibration resistance is mimicked by closely packed 10-millimeter-diameter glass spheres, in which the fragile circuit sits. To test their system, Yoon and Park placed it inside a bullet and used an airgun to fire it at an aluminum wall.

Science! Personally, I can get behind any research that involves playing with airguns in the lab. And this is about more than being able to drop your iPhone without the electronics going all wonky. It will also help protect, say, the electronics in airplane flight recorders, making it less likely that critical information will be damaged in the event of a crash.The scientists found that their mechanical shock-absorbing system reduced the failure rate of the microelectronics from 26.4% (using the conventional hard resin method) to 0.7%, despite the fact that the microelectronics suffered shock levels as high as 60,000 g.

Other applications being bandied about include using the shock absorber system in "bunker-busting bombs", and to protect spacecraft from space debris (a growing problem, especially given our current reliance on orbiting satellites for communications). It might even be useful in Formula One racing, protecting drivers from serious brain injury and internal damage suffered during the inevitable accidents.

I have another suggestion for a possible application: protecting football players from concussion, a serious problem that the NFL is seeking to address with a new sideline concussion test for its players. (The New York Times ran several excellent articles on the topic this week.) A concussion, remember, is not the same thing as a bruise on the brain. There's usually no swelling or bleeding. A concussion occurs when the head accelerates too rapidly, and/or decelerates too suddenly, or is twisted or spun in some way. Symptoms include confusion, blurred vision, memory, loss and nausea -- sometimes unconsciousness, but not always.

 Sure, professional players are required to don safety gear, including protective helmets, but according to this article in Technology Review, a helmet can't completely prevent concussions. In fact, while several manufacturers of sports equipment tout the superior safety of their helmets, Mike Oliver, the executive director of the National Operating Committee on Sports Atheletic Equipment, told Technology Review that "we know from the test data that all the helmets [on the market] are nearly identical [in performance]."

How can this be? Think back to the lowly woodpecker and how it strikes the tree trunk with its beak in a straight, linear fashion. That's key, because head injuries -- in football and beyond -- aren't just the result of linear acceleration, but also too much torque, in which the head rotates or twists. According to Oliver, "The brain is very sensitive to torque, some scientists think this also causes tension between the brain and brain stem." Researchers are currently working with sensor-equipped helmets to better understand all the forces acting on the head during a football game that could lead to concussion, or worse.

Here's some alarming statistics: a 2000 study of NFL players found more than 60% suffered at least one concussion in their careers; 26% suffered three or more concussions. Those players also reported issues with memory, concentration, speech, and headaches. And the damage extends beyond their active careers: a 2007 study examined nearly 600 retired NFL players who'd had three or more concussions in their careers, and found that 20% of them suffered from depression -- three times the rate of players who had never suffered concussions.

Depression often leads to suicide, like in 2006, when former football player Andre Waters shot himself in the head. Postmortem analysis of his brain tissue showed signs of a degenerative disease called chronic traumatic encephalopathy, more commonly found in boxers (who are also highly prone to concussion). And this year, the NFL community was stunned when former Chicago Bears star Dave Duerson shot himself in the chest, right after texting his ex-wife asking that his brain be donated to the NFL's brain bank for further study. There may have been other contributing factors to Duerson's tragic suicide -- he was having personal and financial problems -- but he also was experiencing worsening short-term memory loss, blurred vision, and chronic pain.

See? I told you it wasn't a stupid question. It's easy to snicker at seemingly superfluous scientific research, but in this case, something as trivial as looking a bit more closely at a woodpecker could one day help stave off brain damage in NFL players. Maybe it's too late for Dave Duerson, but it's not too late for tomorrow's gridiron stars.

 

how many horses under the hood..? none - i've got cows.

In February, I had the privilege of attending the 12 Hours of Sebring, an American Le Mans Series (ALMS) race.  The ALMS series isn't as familiar to people in the US as NASCAR, the series that originally got me interested in cars. Drivers in both series have accents; however, in NASCAR, you're distinguishing the Virginians from the North Carolinians, while in ALMS, you have to be careful about confusing the Spanish, Mexicans and the Brazilians or the Australians and the Brits.  (And then there are the 'citizens of the world', but that's a story I will tell later).

In comparing the two types of racing (stock cars vs. sports cars), NASCAR is like hockey and ALMS is more like baseball.  At a NASCAR race, you constantly scan the track to see where the action is.  Except at superspeedways and road courses, you really can't hold a conversation because of the noise.  You have to wait for cautions to communicate with your seat mates (or text them).

ALMS tracks are longer:  three to five miles compared to the typical half-mile to two-and-a-half mile NASCAR track.  When you go to an ALMS race, you position yourself near your favorite turn.  The cars run past, then you have a minute or so to talk before they come back around again.  Drinking while watching racing is common (if not mandatory); however, NASCAR's official alcoholic beverage is Coors Lite, while ALMS's is Patron Tequila.  I'm a sucker for good tequila and a British accent, so I had a lotof fun at Sebring.  Besides, where else are you going to see an Aston Martin sponsored by Lowes?  

ALMS is a good platform for automotive industry companies pursuing greener products.  The Michelin Green X Challenge, which rewards the fastest and most energy efficient cars, considers only gasoline usage at the moment, but as the series evolves, they will likely expand to include another major contributor to petroleum use in cars:  oil.  One of the series' sponsors, G-Oil, is a motor oil with animal origins.  One of the principles of "green racing" is to minimize petroleum usage to lessen our dependence on foreign energy sources, so using a domestically available source for motor oil certainly addresses that point. 

Oil plays many roles in the engine, including protecting metal parts from wear due to friction and carrying heat away from the engine.  A typical passenger car uses about 5 quarts of oil.  Changing the oil every 5,000 miles means you go through about 100 quarts of oil in 10 years.  That doesn't sound like much, but multiply that by the number of cars in the country and the number of people who don't recycle used oil.  The Environmental Protection Agency (EPA) says that two hundred million gallons of used oil are improperly disposed of each year.  So not only are we increasing our dependence on petroleum, the used oil can contaminate groundwater and kill vegetation.

Gasoline and petroleum-based oil come from the same source: crude oil.  Crude oil contains a veritable zoo of hydrocarbons - chains (or rings) of carbon atoms with hydrogen atoms attached to any free carbon bonds.  The number of carbon atoms in each molecule ranges from 1 to 80 or more. The chart below gives you an idea of how many carbons are in the molecules that make up various petroleum products.  Red lines represent gases, blue lines represent liquids and green lines represent solids.  The darker blue tells you where the majority of the molecules in the substance come from.

The same length carbon chain molecules can be used for different things, depending on how the atoms are attached within the molecule.  Isomers are molecules with the same atoms, but different arrangements of those atoms.  For example, there are 355 isomers of C₁₂H₂₆ (a molecule containing 12 carbon atoms and 26 hydrogen atoms).  So even though a narrow range of carbon number is present in gasoline, There may be as more than 500 different molecules involved.

A barrel of oil is 42 gallons, with a typical barrel providing about 19.5 gallons of gasoline, 9 gallons of fuel oil, and 4 gallons of jet fuel.  The remainder is used in a wide variety of products, including grease, kerosene, bitumen (the binder in asphalt), crayons and plastics.  Motor oils are about 90% base oil (the 'motor oil') you see in the chart above, and the other 10% are additives to decrease friction, increase viscosity, prevent corrosion and oxidation, etc. 

Saturated and unsaturated fats are just as important for cars as they are for our bodies.  (The general agreement as far as nomenclature is that fats are solid and oils are liquids.)  Each carbon atom can make four bonds.  Hydrogen can make just one.  Saturated fats - like animal fats - have single bonds between carbon atoms, and single bonds between each carbon and hydrogen atom, as shown in the top part of the figure below.

Unsaturated fats (or oils ) have a double bond between the carbon atoms and each double bond decreases by one the number of hydrogen atoms in the molecule.  Unsaturated fats have fewer hydrogen atoms than saturated fats.  If there's one double bond, the fat is unsaturated, and if there is more than one double bond, the fat is poly-unsaturated.(Thanks to Juan for pointing out that the original in this figure violated the most fundamental laws of chemistry!)

Double bonds are more exposed than single bonds, making them more likely to react. A particular challenge is oxidation, which cleaves the carbon chain at double bonds.  The extra reactivity of unsaturated fats means that the human body can break them down faster and easier.  Unsaturated and polyunsaturated fats are used more quickly in the body’s metabolism, while saturated fats hang around and clog up your arteries.

In your car's engine, hanging around is what you want.  Motor oils use saturated fats because they are more stable.  You've probably never had motor oil go rancid on you, have you?  Saturated fats stay in their fatty form far better than unsaturated fats.  Saturated oils are good for your car, even if they are not so good for you.  One of the problems with double bonds, though, is that they are much more likely to oxidize, which cleaves the double bond and produces two shorter molecules, neither of which has as much protective ability as the original long-chain molecule.  The propensity for oxidation increases with temperature, and engines get very hot. 

The desirable properties of the oil come from the particular molecules that are present.  Motor oils are usually somewhere around 16-20 carbons per molecule.  It doesn't really matter where the oil comes from:  it can be separated out of crude oil or, in the case of G-Oil, it can come from animal fat. 

G-Oil is made from beef tallow - tallow was historically used for candles, as it was cheaper than wax. Oil obtained from refining crude oil is obtained by separating out different components from the crude oil.  Animal or plant fats offer some advantages in terms of processing because they contain high levels of triglycerides. 

Triglyceride is a very large molecule composed of one glycerol molecule and three fatty acids. The fatty acids are represented R1, R2 and R3 in the picture to the left.  The triglycerides go through a process called transesterification, which frees the fatty acids from the glycerol.  Remember learning about how the pilgrims made soap from animal fats and ash?  This is exactly what they were doing.  The glycerol is used in soap and the fatty acids that were left were used to make candles or other products.  This is also the first step you would use to make biodiesel from fat.

It turns out that the fatty acids in beef tallow have very high proportions of carbon chains in the C16-C18 range, which is the target range for motor oil.  Green Earth Technologies, the company making G-Oil, has a patent pending process that converts the fatty acids into the types of chains needed for motor oil applications.  

You might wonder why they don't use plant fats, and that's just because the animal fats are closer to the right composition of molecules.  Plant oils have a much larger fraction of unsaturated hydrocarbons.  The G-Oil website points out that grape seed oil is rich (70-80%) in Omega-6, an 18-carbon chain with two double bonds.  These molecules degrade much faster than those in the animal fats.  The end message is that the plant fats are better for use by people and the animal fats are better for use by cars. Green Earth Technologies points out that the amount of beef tallow they use is a small percentage of what is already being produced as a by-product of meat processing.  

The oil -- and all of it's additives that protect it from oxidation, ash production, etc. -- are biodegradable, meaning that it breaks down within about a month when in contact with common environmental bacteria.  Which means that, no, the oil will not biodegrade in your engine.  I guess if you are a committed vegetarian, you might choose not to use this produce because it is animal-based, but other than that, this is pretty nifty idea.

Perhaps most importantly, you don't have to sacrifice performance for being green.  The oil was tested against a couple leading synthetic and crude-oil-based motor oils and G-Oil compares very favorably. The ALMS series believes that motorsports is a good platform in which to test things that eventually could appear in passenger cars, as is noted on the hauler set up of Drayson Racing (shown below).  Lord Drayson, the co-owner of the team with his wife, is the UK's Minister of Science and Innovation, a very cool guy who actually tries to explain what is going on in Science and Engineering to the public via twitter.  I wonder what U.S. Secretary of Energy Paul Steven Chu drives...? 

I haven't explained the role of nanotechnology in lubrication:  that will be coming in my next post because it turns out the solution is bigger than I originally thought!

 

 

making the break

So, the Spousal Unit took off this morning for a conference somewhere in Wisconsin and left the Resident Feline and I alone with the brand new flat-screen TV. This is what happens when I ask the Spousal Unit to stop off at Circuit City on the way home from the office because I need a more advanced science-y calculator. Not that we're complaining, because the new TV is teh awesome! We played hooky from calculus, plopped ourselves on the couch and wasted the afternoon watching Witchblade on DVD. Anyone else remember that short-lived series on TNT ("We know drama!"), loosely based on the graphic novel series published by Top Cow?

Witchblade was one of my guilty pleasures -- guilty because, frankly, it was a very uneven production, with tacky symbolic imagery, major chewing of the scenery by the supporting cast, and some truly horrific dialogue at times. (There's an entire scene in the first non-pilot episode, "Parallax," where the characters literally speak in koans. While playing chess. It's cringe-inducing.) But the series also had a killer soundtrack, a genuinely compelling underlying "mythology," and Yancy Butler starring as Sara "Pez" Pezzini, a NYC cop who finds herself wielding a mysterious ancient bracelet that turns out to be pretty damn useful in a fight.

Butler made the series, frankly. She took a comic book character known more for her exaggerated pulchritude and skimpy outfits, and transformed her into a street-smart, tough, sexy, emotionally complex woman -- who just happened to play a mean game of pool in the bargain. Yancy Butler kicked butt, literally and figuratively.

My favorite scene  in the two-hour pilot is Pez taking on every guy in the local bar in successive games of pool, and handily sinking every shot after the break in each game. She pockets a nice chunk of change, too. This, frankly, is a common fantasy among women. I am no exception: in my dreams, I can walk into any bar and wow the locals with my prowess.

Alas, far from being a skilled pool shark, I am utterly inept at the game. I'm not being modest. It's a thrill if I manage to hit the cue ball correctly, and if it also hits one of the object balls and gets it to move a tad, huzzah! Actually sinking one of the object balls pretty much makes my week.

Lots of people throughout the centuries have had a similar fascination with some form of pool, notably billiards. (For simplicity's sake, I'm not going to go into the many variations made popular all over the world. Follow the various links and you'll learn more than you ever wanted to know about cue-stick games.) The game has its roots in a lawn game resembling croquet, dating to 15th century Europe. Perhaps folks tired of having their games rained out or something, because eventually the game evolved into an indoor tabletop version, whereby balls were shoved (not struck) with wooden sticks called maces. Originally there were only two balls, as well as a wicket (hoop) and a stick as a target, but eventually people figured out that you really just needed the balls and cue sticks and a few pockets around the table to have a kick-ass game. There's even a reference to billiards in Shakespeare's Antony and Cleopatra.

The iconic image of pool or billiards (in the U.S., at least) is the 1961 movie The Hustler, starring Paul Newman. It's a dark, fairly gritty film, actually, but for some reason it inspired a billiards revival, even though pool was a game of ill-repute in many American communities in the 20th century. The game went highbrow again two decades later, when Newman played an aging pool shark mentoring Tom Cruise's ambitious young hustler in 1986's The Color of Money. And while the prevailing image is one of a boozy boy's club, women have always indulged in billiards, although they weren't officially organized until 1976, with the birth of the Women's Professional Billiards Association. Just a few years before, a grandmother named Dorothy Wise won five U.S. Open tournaments, proving once and for all that it wasn't just a "man's game."

There's a certain degree of practiced skill involved, even to become adept at the basics, even more so if one aspires to learn some of the more advanced shots, or tricks. And like most sports, there's a great deal of physics involved in the seemingly simple game of pool, as evidenced by the large number of online resources outlining the specifics in detail. It's standard classical Newtonian stuff, mostly: overcoming the cue ball's inertia, accounting for friction from the table's green felt surface, the transfer of momentum between the cue ball and the object ball when they collide (it's not a perfectly elastic collision, but close enough), and so forth.

The paths the balls take after colliding depends on the above factors, as well as the angle at which the cue ball hits -- which in turn depends on where the cue stick hits the cue ball, which depends solely on the player's skill and control (or the lack thereof, in my case). Draw and Follow shots, for example, involve (respectively) hitting the ball below center to put a backwards rotation on it, or hitting above the center to put a forward spin on it. If we can figure out how to measure the mass, position and velocity of each ball on the table at the time of collision, we should in principle be able to predict the path and outcome of the shot.

Ah, but that's just too easy for some people. I found this entertaining online tutorial via Google on Quantum Billiards: what might it be like to play pool at the subatomic level, with balls the size of protons? Things can change in an instant when an observation is made, you can't now both the position and momentum of any ball at the same time, and each event has many possible outcomes, not just one. You're pretty much just taking shots in the dark. And don't forget about quantum tunneling! Normally a bank shot lacks sufficient energy to hop over (or through) the cushioned barrier of the billiard table; instead, it is reflected off at predictable angles. Not so if the ball is the size of a proton. Because its tiny mass creates large uncertainties, there's a much higher probability it could go right through the cushioned barrier. Electrons do it all the time, why not subatomic billiard balls?

Of course, if you really want to make things interesting, you need a spherical cow model for billiards, and a recent paper accepted by Physical Review Letters apparently offers just that. Physicists at Boston University studied what would happen during the initial "break shot" of a billiards game in an ideal setting: namely, with no dissipation of energy (I assume this means a perfectly elastic collision, with nothing lost to heat, noise, etc.) and an infinite billiard table. Heck, if we can have billiard balls the size of protons, why not infinite tables? (Or even quantum versions of Cruise and Newman?)

Basically, they created an ideal gas and then sent the particles careening all over the place, from a central starting point. Their conclusion: "Just as in real billiards, progressively more particles become mobile as the collision cascade develops." But there was an interesting twist. The initial break is, naturally, asymmetric, with various balls flying off in different directions and speeds. But in the idealized model, as the balls (or particles) expanded outward, the region became nearly spherically symmetric around the initial point of collision. In fact, it looked for all the world like a shock wave generated from an explosion. Now that is freaky.

Shock waves do form when the speed of a gas changes by more than the speed of sound. Wherever this happens, according to Wikipedia, "sound waves traveling against the flow reach a point where they cannot travel any further upstream and the pressure progressively builds in that region, and a high pressure shock wave rapidly forms." Something similar happens with supersonic jets: parts of the air around the plan travel at exactly the speed of sound, along with the aircraft, but the plane leaves a pile-up of these sound waves in its wake. The waves are forced together and compressed -- sort of an amplification effect -- ultimately merging into a shock wave that spreads out sideways.

Thunder is a naturally occurring sonic boom, and yet another example of a shock wave. And of course, explosions generate shock waves, such as when a bomb goes off. It just hadn't occurred to me that colliding billiard balls might also produce a shock-wave phenomenon. But when the collisions are viewed in slow motion, as in the YouTube video below, it does seem a bit more explosively violent than when observed at full speed:

Here's one last bit of trivia to relieve the Monday morning doldrums. Apparently the cracking sound of a bullwhip is a tiny sonic boom. The end of the whip has far less mass than the handle, so swinging the whip sharply, energy is transferred down the length of the whip. The velocity of the whip increases as mass decreases, such that ultimately the end (called the "cracker") moves faster than the speed of sound -- one of the first human inventions to break the sound barrier. I'll bet Sara Pezzini swings a mean bullwhip, when she isn't shooting pool.

it's just a flesh wound

Martial arts and personal injury seem to go hand in hand. In my decade or so of jujitsu training, I broke two toes, dislocated my wrist, endured countless bruises and sprains, fractured my right elbow, and had my back thrown seriously out of whack thanks to a powerful guillotine choke administered by an over-enthusiastic ex-Marine. Most notably while practicing self-defense techniques against a long bo (actually a stickball bat) for my black belt test, I miscalculated during a duck-under technique, came up too soon, and received a nasty thwack! on the forehead that dropped me to one knee. It didn't actually hurt; I was mostly stunned. Then the blood began to gush, and I realized mat time was over, and I'd be spending several hours in the ER instead. The slash went clear down to the skull cap, and required 14 stitches to close. I still have a jagged scar across my forehead, although few people notice unless I point it out. (Also? No need for future botox treatments in that area, since the tiny muscle that causes frown wrinkles got sliced clean through. I literally cannot frown in that portion of my forehead.)

And I still loved every minute of my training. It's just part of the rite of passage when one is seriously studying the martial arts, but to outsiders, it can seem a bit, well, extreme. (A friend of mine became so upset at the perceived brutality of my black belt test, he literally had to leave the room at one point.) I was reminded of my halcyon days sweating and bleeding with my fellow jujitsu practitioners when I received an email from my friend Jim D., who started training in Tae Kwon Do a few years ago with his teenaged son, and recently passed his brown belt exam. Jim fractured his wrist this past week when he agreed to hold six pine boards while his instructor attempted to break them with a kick. Apparently, the instructor missed the central target area and the full force of his kick landed off to the side, so all that kinetic energy (or should one say momentum? Terminology can be so confusing!) went into Jim's wrist instead of into the board. Ouchie! At least he has a very impressive looking cast with which to impress the laydeez:

Anyway, Jim took the injury in stride, like any respectable martial artist. But he's the curious sort, so he emailed me asking if I knew anything about what went on from a physics standpoint to bring about his injury. I've done lecture/demos on the topic, focusing on broad concepts as opposed to specific calculations, so I knew a little, even though I never featured board-breaking in any of my lectures. Frankly, I've never understood the point of such an exercise. I'm an adherent of the Bruce Lee philosophy, immortalized in Enter the Dragon: "Boards don't hit back."

Except in the strictest physics sense, they kinda do. Per Newton's third law, momentum is conserved, and that translates into the well-known maxim of equal and opposite reaction. Many of us remember this from our introductory physics classes (or the equivalent thereof): If an object exerts a force on another object for a specific length of time, the second object will react by exerting an equal but opposite force for the same amount of time. So a board does "hit back" in that sense. The force generated by Jim's instructor created a reaction force in the opposite direction when his foot made contact with the boards; the boards gained exactly the amount of momentum the instructor's foot lost, or almost as much; some would have been lost via conversion into heat or noise energy, for example. The boards accelerated in the opposite direction in response to the kick.

A board will break when the part that is hit -- ideally the center -- is infused with more energy than its structure can handle, causing it to crack and/or break. But not every part of the board accelerates uniformly. The part that took the brunt of the kick -- again, ideally the center, although unfortunately for Jim, in his case it was off to the side -- accelerate much more than the surrounding piney-parts. This produces a localized strain, and if the strain becomes too great, the board will crack in that locale. As for how much force went into Jim's poor wrist, I could only offer the grossest generalities. For someone weighing 140 pounds, traveling at a final velocity of about 10 MPH when s/he hits the target, that person's body would have about 504 joules of energy. But that's assuming a full-tilt run and putting one's entire body mass behind a kick. Chances are, only a portion of one's body mass will be used -- although a TKD instructor, one assumes, would have excellent technique, and would therefore employ a greater percentage of his/her overall body mass than the average untrained kicker.

I told Jim if he wanted a truly thorough answer to his question, rather than the generalities I could offer, he should contact Jearl Walker, physics professor at Cleveland State University in Ohio, longtime contributor to Scientific American, and general all-around daredevil scientist, trying his hand at firewalking, lying down on a bed of nails, and investigating the physics of the martial arts. (He has a book -- and a Website -- called The Flying Circus of Physics detailing various real-world illustrative examples of physics concepts, as well as a blog.)

Per Walker, the force required to break a standard single 3/4-inch pine board is about 3000 Newtons; the force required to break a solid pine block of the same thickness as six stacked standard pine boards is astronomically higher: six times higher, as one might expect (6 x 3000 Newtons), [CORRECTION: I didn't read my hastily scrawled notes correctly: that should be 6 CUBED x 3000 Newtons. Yowza! 6 pine boards would be about 18,000 Newtons and change.] although there are numerous variables, such as whether the boards are warped, how many have knots (which make them harder to break), and how much space is between each board. Still, that's a pretty good ballpark figure. To phrase it in slightly different units, it takes about 5 joules of energy to break one board, and about 30 joules to break six. And a large fraction of that energy went into Jim's wrist instead of into the board. (Also per Walker, it was the focused shock wave that broke Jim's arm, not a static wave of energy.)

I think it would be a bit more difficult to determine the force of impact of my old head injury, although if any of you are bored over the weekend and care to give it a shot, we'd all be interested in hearing what you came up with. The mass of the stickball bat could probably be estimated, along with the respective body masses of me and my friend Jordan, who was swinging the stick. Then we'd need to estimate the speed of the swing (Jordan's pretty big, and strong, and to his credit, respected me enough to not pull his punches, so to speak), and how fast the stickball bat was traveling when it struck my head. The hardness of my head might also be a factor; all materials have their own varying degree of elasticity, after all. Complicating matters is the fact that both Jordan and I were moving when the injury occurred, and because of that, it was more of a sharp, glancing blow that slashed across my forehead at a downward angle. That's probably why I escaped without a concussion or more serious skull fracture.

Of course, like most head wounds, it bled like crazy. There are a lot of arteries, veins and capillaries in the head, since the brain requires a constant supply of oxygen- and glucose-rich blood to function properly. Also, I'd been exercising for a good hour by then, so the blood was really pumping. Funny side story: My chief instructor was chatting with a visitor to the dojo when my head injury occurred, his back to the mat. The visitor, gazing at the gushing blood in horror, mentioned that I'd been hurt, and really, oughtn't someone to do something? My instructor was used to people worrying about my welfare (there were very few women in my chosen style, and a hard fall from, say, a judo throw can look much worse than it really is). So he just waved it off and said, "It's okay -- she gets back up." Quoth the guest, "But... but... she's bleeding all over the mat!" That got his attention. He swung around, and immediately warned, "Don't you bleed on my mat!" Too late!

Ironically, when I examined my gi upon getting home, there was hardly any blood on it at all, just a bit of staining around the collar when the ER doc rinsed the matted blood from my hair. It had spurted outward in impressive gushes, hitting pretty much everyone in the vicinity except me -- just like the Black Knight's arterial sprays in Monty Python and the Holy Grail. ("It's just a flesh wound!") That's not what I would have expected.  Granted, we aren't talking about arterial spatter of the sort one sees routinely these days on C.S.I. Still, the blood pumping through my head at that point was clearly moving at a high enough pressure to cause an arterial-like spurt. Which meant I didn't need to soak my gi in bleach for two days, like a few of my unfortunate fellow students. (One guy -- who kindly administered pressure to my wound to stem the bleeding while waiting for the ambulance to arrive, and thus had my blood all over him -- just gave up bought a new gi. Thanks, Vito!)

The C.S.I. franchise certainly has its critics when it comes to how it depicts forensic science, but in fact, there is such a thing as bloodstain pattern interpretation that can be used to piece together the events that gave rise to a particular pattern of spatter or bloodstains. Experts trained in this approach consider such qualities as the viscosity of blood, the specific gravitational forces acting upon it, and the role of surface tension. (For instance, a bit of blood that falls off a pricked finger will round out into a sphere because surface tension acts to reduce surface area to the absolute minimum possible.) Here's some fun facts I learned about blood spatter (illustrated by some handy photos) from this excellent Website:

* Blood cast from a moving source will make smaller droplets than blood cast from a stationary source.

* Blood follows the same basic laws of physics as any projectile in motion. (This means it should be possible, in principle, to calculate the trajectory of the blood spurting from my head wound and predict where it would land on the mat, so everyone could steer clear of that spot.)

* The terminal velocity of a falling blood drop depends on its size: smaller drops have a lower terminal velocity and reach that point after a shorter fall distance that larger droplets (which accelerate over a greater distance and thus reach a greater terminal velocity).

* The shape of the blood spot depends in part on the texture of the surface on which it calls. If it falls on smooth glass, it will be circular and fairly uniform in shape. If it calls on a textured surface, such as paper, or wood (or a judo mat), the shape won't be nearly as regular. In general, the harder the surface, the less spatter there will be. If a blood drop hits a surface that is both hard and smooth, it will break apart upon impact into smaller droplets -- and those offspring droplets will continue to move in the same direction as the parent drop.

* The angle of impact also determines a blood drop's final shape. For instance, a vertical drop onto a smooth target tilted at 90 degrees results in a circular stain, and as the angle decreases, the stain becomes more elongated, and its length-to-width ratio increases accordingly.

* Finally, blood spatter patterns are classified according to the velocity with which the blood struck a given surface. For instance, spatter patterns occur when blood is projected at a velocity greater than the force of gravity, such as what occurs when blood is cast off a weapon. (Per the site, "The direction and origin of the backswing is often clearly discernible.") Low-velocity blood spatter is basically what happens when the stuff just drips downward from a cut. A blow with a baseball bat would constitute medium-velocity blood spatter, producing spots of about 4 mm in diameter, while a gunshot will produce high-velocity spatter and a "fine mist" of spots less than 1 mm in diameter. Arterial spurting is a category all its own.

The Black Knight would have been fascinated, I'm sure, to hear King Arthur ruminate on these matters (far more interesting than determining the air speed velocity of an unladen sparrow, both African and European varieties). There's much, much more to do with the science of blood spatter, and the physics of the martial arts (judo throws are a specialty all their own), but I suspect I've grossed everyone out enough for one day.

built for speed: part deux

Today we bring you Part Deux of our awesome Q&A with Diandra Leslie-Pelecky, a physics professor at the University of Nebraska, Lincoln (in the process of relocating to Dallas, Texas) and author of The Physics of NASCAR: How To Make Steel + Gas + Rubber = Speed. If you missed it, you can read Part I here. Also check out her Website and schedule of speaking engagements. And oh yeah -- buy the book!

Q: As a woman in physics, you're sensitive to gender dynamics, and NASCAR is another male-dominated sport. Did you notice some differences?

DLP: I'm so used to being one of the few women in a room that the composition of the NASCAR garage and shops didn't strike me as unusual. NASCAR is a little more male dominated than physics, but I think the bigger difference is between non-profit academia and a for-profit, high profile professional sport. I have yet to see young women waiting anxiously outside the door for the speaker after a particularly good talk at the APS March meeting. [The Spousal Unit would like readers to know that he heartily approves of the concept of physics groupies, and thinks this should become de rigeur at conferences. In fairness, he believes that female speakers should have groupies, too.] The fact that all the drivers are male and there are very enthusiastic female fans changes the male/female dynamics significantly compared to a situation in which it is assumed that everyone is there -- male or female -- for their job.

The people who work in the shops and the garage (and the NASCAR officials) are a much more diverse group than the drivers.  There are a number of women working for NASCAR in the technical inspection line, and during races in the pits. There are a few women on the garage and pit teams, but not many. I went to my first testing session in Vegas a couple of weeks ago and was pleasantly surprised to find a number of women engineers. Some come to the track only for testing, when the teams are allowed to use data acquisition tools on the cars. I had only been to races, and many of the women I saw at Vegas work primarily at the shop.

The garage environment is a little like a frat house. There are a lot of practical jokes and put-downs and a lot of "guy humor." The environment in the engineering departments of most shops may be a little more professional. (I realize that sounds like I'm comparing research-intensive universities with frat houses. I'm not, but I do think many research universities tend to be more competitive and less collegial.) NASCAR is also very high pressure, because if you are, for example, on the pit crew and you screw up, you do it in front of millions of people and it could literally cost tens or hundreds of thousands of dollars.

Physics is a little ahead of NASCAR in terms of numbers, but there are a lot of similarities. The most important thing, I think is early parental involvement. If you talk to most women in science, they will tell you they had extremely supportive parents. The same is a requirement for racing, especially because racing is expensive. Kids get involved at age 7 or 8 in go karting, and advancing up the ranks isn't cheap. The prospect of getting physically hurt is a bit of a difference between science and racing. I'll stick with a theoretical understanding of impulse, thank you.

Q: One of the strengths of your book is that it brings a strong narrative structure to a story in which, as you once told me, "the main character is momentum." Why did you decide to do that, and what can other scientists learn from this about effective ways to communicate with broader audiences?

DLP: The narrative structure just seemed to work as a way to take the reader along with me on the trip. I'd love to say I planned it that way, but the end book I delivered to Dutton was very different than the one I expected to write. I sort of fought the narrative structure at first. For example, it was really hard for me to write physical descriptions of people. First, I often realized after I left an interview that I couldn't actually remember what the people looked like and I was so focused on the science that I hadn't written anything down. Second, I felt uncomfortable writing that someone was graying, or heavy, or balding. And the longer I was around the garage, the more I couldn't help but feel for the people I was watching. I couldn't write dispassionately about the struggles the No. 19 team was having last year, or the disappointment Andy Randolph felt looking at the blown engine from Fontana.

I went to a screenwriting workshop called Catalyst and the most important thing I took away from that is that there has to be something your audience cares passionately about. That almost always involves people. Science isn't done in a vacuum. (Okay, technically, it is, but I meant there is no science without the people doing it.) The thing that scientists and the NASCAR people have in common is passion. Passion allows you to work 60 hours a week without realizing that you're doing it. The Physics of NASCAR shows people that science doesn't just happen in laboratories.

Q: Who is your target audience?

DLP: My book is meant for the NASCAR fan who doesn't know a lot of science, or the science fan who doesn't know a lot about NASCAR. The writer Margaret Wertheim pointed out that people who are already interested in science are very well served. It's the people who don't know that they're interested in science that we fail. NASCAR has 75 million fans. If this book gets even a very small percentage of them to think about taking a science course, or ask their teacher about springs, I will be thrilled. My goal is to stimulate people's interest. They'll learn some science from reading the book, but I hope the book will inspire them to look further and ask their own questions.

I think we often miss that what is interesting to us as physicists is not at all interesting to most people. Students usually have three questions: "Why do I have to learn this?", "When am I ever going to use this?", and "Is this going to be on the test?" We usually only have a good answer to the third one. How can you have a position about alternative fuels if you don't understand how an internal combustion engine works? Every year, I talk to my students about engines in the thermodynamics unit, and I talk about real engines. Inevitably, I get a few students who will email me and ask, "If the internal combustion engine can never be really efficient, why aren't we looking for alternatives?"

You don't have a right to have an opinion on things you don't understand. If you can't explain what a stem cell is, you shouldn't be lobbying for or against using them. We need to be teaching students the science they need to function in today's world. 

Q: Have any of your physics colleagues expressed dismay about taking such a "popular" approach? It's a common criticism of such books. How would respond to that criticism?

DLP: I blame it all on NSF and NIH. If they funded more of my research proposals, I would be so busy in the lab that I wouldn't have time to write about NASCAR. I've been bombarded over the last few weeks with pleas from the scientific societies to write my elected representatives because the US budget for science this year is a disaster. Those of us in schools from kindergarten to universities are responsible for the people who made these decisions.

Look at people like Leon Lederman and Carl Wieman, who stopped doing physics research per se and are focusing on education issues because they believe that solving these problems is more important than publishing another paper in Physical Review (sorry Phys. Rev.). When you get to heaven, St. Peter is not going to ask for your academic C.V. It's an important enough problem that what other people think or say isn't really a factor.

I've been working with teachers from elementary to high school for more than 10 years and frankly, I'm frightened by much of what I see there. Even the best teachers are paralyzed by the implementation of the idea that we can prove that students are competent at science by giving them multiple choice vocabulary tests. We are teaching kids that learning is nothing more than rote memorization of unrelated facts they will never use again. They get to college or the workforce and are shocked to find that your results and not your intentions are what matters. They can't write persuasively. They can't read a chapter from a book and pull out the main ideas. The best of our students will be the best in the world, but I fear that the distribution is getting broader and broader. We are not doing well by the majority of the students we educate and, in the end, it is going to come back and hurt us as a country.

I've gotten a lot of encouragement from my colleagues at Nebraska. That may be because we have a long tradition of writing books about the physics of sports, starting with The Physics of Golf by Ted Jorgenson, The Physics of Football by Tim Gay, and now my book. We're taking bets on which of the current crop of assistant professors is going to be writing The Physics of Professional Wrestling in a few years.

Q: You've written The Physics of NASCAR which -- if there is any justice -- should be a huge success. What's next?

DLP: My father's favorite saying was, "Life is not fair." So I'm trying not to get any expectations up. My next writing projects are going to be research grant proposals. I'm hoping that my experience writing this book has made me a more convincing proposal writer as well.

I just wrapped up working on a television program on the science of the new car for VOOM HD networks. That project is headed up by Brad Minerd, who did the spots with my colleague Tim Gay for NFL Films. Brad is now at NASCAR and gave me the opportunity to consult on the show. It was a really interesting experience to see how television programs are put together. It is even more of a challenge to put science into a very short TV program than it is to write a [popular science] book.

As for a second book, I've heard from F1 racing people talk about finding ways to harness the innovative minds of the people in motor sports to generate ideas that could be used in consumer automobiles. For example, limiting how much gasoline the team gets for a race would force them to think about ways to capture some of the energy from the engine that is normally wasted, such as the motion of the flywheel, or heat.

As a country, we have to make some really tough decisions about energy, and I don't think most people have the information they need to make an informed decision, so I'm thinking about how there might be a way to do something along those lines. I also have an idea for a NASCAR-themed romantic comedy about an aerodynamics engineer who falls in love with a NASCAR driver. It seems like a healthy challenge to get the Navier-Stokes equations and a kiss in the same line of dialogue!

built for speed: part one

It's a very special day at the cocktail party, because we're featuring an extensive Q&A interview with Diandra Leslie-Pelecky, mediagenic condensed matter physicist  extraordinaire and author of a terrific brand-new book: The Physics of NASCAR: How To Make Steel + Gas + Rubber = Speed. It's so extensive, in fact, and so substantive, that we're splitting it into two parts: Part I (this post) focuses on some of the actual science behind the sport and her adventures hobnobbing with the NASCAR crowd. Part II will be posted tomorrow and will focus on the broader issues of gender dynamics, effective communication of science to diverse audiences, and making NASCAR vehicles of the future more energy efficient.

This book's publication is particularly gratifying because I've known Diandra for years. We met at an academic/industrial workshop sponsored by the American Institute of Physics sometime in the 1990s, hit it off -- it helped being two young women of roughly the same age in what was usually a roomful of men -- and over the years became good friends, despite living in completely different parts of the country. And it's always gratifying when one's friends do well.

We've had lots of long dinner conversations over the years about physics, and communicating physics to broader audiences, but I distinctly remember one in particular, just after my first book came out. Diandra mentioned that she'd been thinking a lot about the underlying physics of NASCAR racing, and thought it might make a decent book. "You should totally write that book!" I exclaimed, recognizing (as did she) that it could potentially reach people who would never otherwise have any exposure to physics. I say that a lot to people who have ideas for books; it rarely translates into concrete action. (People have lives, after all, and writing a book is an enormous time- and energy-suck. It can literally consume you.) Blessed with an unusual degree of decisiveness, discipline, and drive, Diandra promptly went out and wrote it.

And she wrote a damned good book, too, packed with fascinating science illustrated by real-world crashes, wins and losses, and colorful anecdotes gleaned from all her backstage visits and interviews with the mechanics, drivers, car designers and so on. She gives a rare peek at how much effort, ingenuity, and just plain good science goes into this seemingly inane sport. I used to catch bits of NASCAR races on TV while flipping through channels, and marvel at how so many people could be so enthralled by a bunch of cars going around a track really, really fast. I get it now. At least a little. There's a lot more to NASCAR than circling around a track. Don't believe me? Buy the book and see for yourself; I suspect you'll get sucked in, just as I did. Check out her Website, and her schedule for speaking engagements. And join me in welcoming Diandra to the cocktail party!

Q: What is it that sparked your interest in writing a book about NASCAR physics? Were you just a really big fan of auto racing?

DLP: I was flipping through channels one Sunday and happened upon a race. Nothing exciting, just a pack of five or six cars going around a turn. I was ready to click to the next channel, but before I could, one of the cars in the pack -- all of a sudden, and for absolutely no apparent reason -- hit the outside wall. I'm a physicist. I know that things don't happen without a reason, so this bothered me a little.

No one was hurt but the car that hit the wall took out a bunch of other cars, so they had a bit of cleanup to do. That gave me time to watch the replays. I saw no tire problems, no engine problems, no contact with other cars. The announcers said something about the car "getting loose" and the other car "took the air off his spoiler." I felt the way I suspect my students feel when I start using physics jargon.

I got on the web, thinking I'd have an answer in 10 minutes. Two years later, here's a book about it. I've always liked writing and I've always liked teaching, but over the last few years, I had really gotten down about teaching. It is very frustrating teaching students who don't want to be there. That's partially our own fault because we do a pretty lousy job showing people that physics has to do with things they care about. When I explained things in class using NASCAR, or even cars in general, the students were more engaged because they could see the connection between what they were supposed to be learning and what was actually happening around them. There are very few other sports in which the link between science and winning is as strong.

The moment of conception for the book goes back to a conversation you and I had at an American Institute of Physics Industrial Affiliates meeting in Bethesda, Maryland in 2005. [Jen-Luc Piquant observes that Diandra has a far clearer, detailed memory of date, time and place than I do.] I mention this because we often forget that what we say to other people has great power. Sometimes a word of encouragement is enough to turn a wild dream into a plan.

I had been thinking about NASCAR and using it to teach physics all summer and mentioned it to you because I'd always harbored this abstract dream of being a writer someday. We are the same age, and I think we had been talking at our table about milestone birthdays. You told me to "Just do it" and sent me one of your book proposals and a referral to an agent. I sat on it for six months, then contacted the agent and figured that it would take a year or two to sell -- if it sold at all. Much to my surprise, it sold rather quickly. Then I actually had to write it!

Q: So what caused that crash you saw on TV?

DLP: The grip of each tire is proportional to how much force is pushing down on that tire. You can get grip two ways: mechanical grip, which is the interaction of the tire and the track, and aerogrip, which is due to air molecules rushing past the body and pushing down on the car, which again pushes the tire into the track. Without aerogrip, you have to slow down around the turns. The amount of aerogrip depends on how fast you're going and how other cars disrupt the airflow around you. If a car comes up behind you just right, they can decrease the amount of air hitting the rear of your car, which decreases how much grip your rear tires have. The car I saw crash lost rear grip and couldn't slow down enough to make the turn.

Q: You had the opportunity to go behind the scenes and interact with the drivers, owners, mechanics, and various others who make NASCAR happen. What were some of the highlights of researching the book?

DLP: The book turned out much differently than I expected because I went into it thinking that I'd talk to the technical people to get background and then write up chapters explaining different topics. I thought the technical people were just in the race shops, but the race track garage is filled with science.

I went to a meeting of the Society of Automotive Engineers Motorsports Conference -- at this point, I didn't know a suspension from a carburetor -- and I met people from F1, Indy racing, drag racing and NASCAR. They were more than happy to answer my questions and they were very welcoming of a total outsider into their group. Not all professional societies are like that.

Josh Browne, who was the No. 19's Crew Chief at the time, was at the conference and I invited myself to "embed" with their team for a couple of races. Josh understands the potential power of using motorsports to get people interested in math, science, and engineering, and he has been (and continues to be) incredibly supportive. The guys on the No. 19 team let me follow them everywhere, ask a lot of questions, and made sure that I didn't get run over in the garage.

I was surprised by the access I was given, both at the track and in the shops. I was upfront with each team that my goal wasn't to spill their secrets, and I got a lot of great stories that ended with, "Oh, please don't publish that!"

Q: You also got to drive one of the race cars, thereby earning the envy of teenaged speed demons everywhere. Inquiring minds want to know: how cool was that?

DLP: The Team Texas High Performance Driving School at Texas Motor Speedway made that a great experience. You have to understand that I'm afraid of basically everything, especially things that I've never done before. Team Texas puts ten cars on the track at a time and each car has an instructor in the passenger seat. I picked Team Texas because I liked the idea of having someone right there, and because they offered the opportunity to do a driving experience and then a ride-along with one of their instructors. I figured if I didn't get the car over 100 MPH myself, I'd at least get the feeling of speed from the ride-along.

I was surprised because I wasn't that nervous waiting for my turn. It's because I was focusing so much on how I was going to capture that experience and all the subtleties for the book. I was concentrating on the track and the signals from the instructor, and I was a little disappointed when we finished and pulled into the pit road because I didn't think we had gone very fast. Paul, my instructor, told me I did a pretty good job for a first tie, and that we had hit the max speed: about 150 MPH. I have a videotape taken from the car, and when I went back and watched, we had passed just about all the other cars on the track. There is an ignition chip that limits the engine rpms, which limits the speed. When I went back to the in-car tape, I could hear when the chip kicked in, which is called "hitting the chip."

I rode with Mike Starr, who owns the Team Texas Performance Driving School. For anyone thinking about doing a ride-along at Team Texas, let me note that when you own the school you get to run in the lead most of the time. The difference between my driving and his driving is that I was doing 150 MPH down the straightaway. Mike was doing 150 MPH around the turns. I thought my head was going to go right out the passenger window -- we were pulling about 2g! While we were driving, they kept the cars pretty far apart, but when we were passengers with the professional drivers, we were going 150 MPH and I could literally have reached out and touched the car next to us. Way cool.

When I got out, I was fine, but after about a minute, I felt like I had drank a whole pot of coffee. My legs were wobbly and my heart was racing. My hands were actually shaking. I thought that maybe my body had finally caught up with my brain and was appropriately afraid.

When I was with the No. 19 team at Atlanta for qualifying, our driver (Elliott Sadler) was one of the last to go out, and he ended up with the second fastest time. While we were waiting for the other cars to finish, I noticed that Elliott was shaking the same way. Josh told me it's adrenaline. It's like winning in Vegas: you get a rush and you want to do it again.

Q: Was there anything that surprised you about the world of NASCAR?

DLP: Almost everything surprised me about NASCAR. In academia, we talk a lot about how open-minded we are, but we all have stereotypes, especially about things that are outside our immediate experience. I had my own stereotypes of NASCAR and most of them were totally wrong.

I was pleasantly surprised by how helpful everyone I worked with has been. I started talking with people like Eric Warren and Andy Randolph, both of whom are PhDs (in aeronautical and chemical engineering, respectively), so we had the common background of having been through the hazing experience known as graduate school. (In both interviews, we ended up talking about funding. Put any two PhDs in a room and they talk about funding.) At my first race, I spent most of my time with Josh and Chad Johnston, who are both formally trained engineers. By my second race at Martinsville, I had screwed up enough courage to pester the mechanics in the garage. That sounds like an upside-down approach, but that's the way it felt most comfortable to me.

NASCAR is largely a meritocracy. If you go to people unprepared, they'll let you know (just like in physics). If you ask intelligent questions and are upfront, they'll be exceedingly generous with their time. No one was ever condescending or rude.

I went into the project thinking this would be like an anthropological expedition: I would stand in the back and take notes and report what I saw. And I guess that's exactly what I started out doing, but what I saw were people passionate about their jobs who work 60-80 hour weeks because they are obsessed with figuring out how to make their car go faster. In other words, people like scientists, except they make better money than we do.

I remember standing on top of the hauler in Atlanta -- it was March, and very, very cold. It was my first time at the track and I hadn't yet gotten the nerve to venture into the garage per se. I could see the track from the top of the hauler, and if I ducked down, I could see into our garage stall. The team wasn't having a great practice, and I remember in particular one time they had rushed to make a change to try to make the car better. The entire crew was standing in the empty garage stall waiting. The driver (Elliott Sandler) came over the radio after a lap and said, "Nope. Not any better." I could hear the disappointment in Elliott's voice and I remember watching Kirk Almquist (the car chief) from the top of the hauler, and seeing his shoulders slump and his head hang when he heard that. You can't watch people who care so much about what they're doing and not be pulling for them to succeed.

Q: You've said that NASCAR drivers are "intuitive physicists." What do you mean by that?

DLP: Drivers can explain impulse and conservation of energy, but they don't use those words to do it. When it comes to racing, drivers are experimentalists and I'm a theorist. How many times have I calculated the centripetal acceleration around a banked curve? You get a number and it's mostly meaningless. You write it down and move onto the next problem. But I have a gut-level understanding of what 2gs feels like now.

Most drivers don't recognize that they are explaining "physics." I have a tape of Elliott explaining his 2003 Talladega accident (a quintuple somersault with two pirouettes and an upside down landing) that I used in my class. [Jen-Luc found a video clip of the accident here, as well as a clip of the all-time worst NASCAR crash to date, for all you morbid rubber-necking types... like her.]  It looks like a very serious accident, but Elliott walked away with literally nothing more than the wind knocked out of him. Elliott explains on the tape that, because he slowed down over a period of time, each hit dissipated a little bit of energy, and he felt a little force, but nothing like he would have felt had he stopped all of a sudden. Well, that's F=dp/dt in physics language. Elliott was surprised to find out we were team-teaching physics.

Jeff Gordon did an ESPN Sports Figures episode in which he explained the difference between kinetic and static friction. When you're going around a turn, you want to slide a little in the radial direction, but you can't slide so much that the car loses grip and heads into the wall. When the car starts sliding up the track, you're in trouble. Jeff says in the tape that his job is to detect the change from static to kinetic friction. He may not have known the words prior to taping, but I guarantee you he can feel the difference between those two types of friction through the seat of his pants in a way that most of us who can write the Lagrangian equations of motion for a race car cannot.

Q: Were you ever tempted to just buy a junker and take apart the engine to see how it works?

DLP: I lucked out having met Dr. Andy Rudolph, who is the Engine Technical Director at Bill Davis Racing. I visited him just after the spring Fontana race, where their No. 22 car's engine had blown up. The engine was in pieces sitting on a cart. The oil pooling around reminded me of blood. Andy was looking at it like a doctor whose patient had left the hospital looking perfectly healthy and now here he was doing an autopsy.

Engine books often show an exploded view of the engine. I got the literal exploded view of the engine, which helped me understand the relationships between the pieces better. The first time I talked with Andy, I didn't even realize that they use pushed engines, but he is a really good teacher, so I think I've got a halfway decent understanding of the engine. [Jen-Luc sez check out this photo of Diandra lookin' all cool and mechanical in the garage with Andy Randolph. You can just hear them saying, "Assume a spherical tire..."]

One of the great things about the people I met is that I'm still in contact with many of them. When they changed the size of the restrictor plate at Daytona, I sent Andy an email that was essentially my understanding of the changes, followed by, "Is that right?" He replied, "Yes, but..." and proceeded to show me another level of science I hadn't thought about.

A NASCAR engine works pretty much like a standard internal combustion engine. What really made me crazy was trying to understand the suspension -- the shocks, springs, weight distributions, etc. The suspension geometry is unique to stock car racing. NASCAR just changed car models, so the old cars, which can't be used anymore, were being sold off "pretty cheap" (meaning tens of kilobucks). I pondered getting one just to be able to understand the suspension a little better, but I'm sure there's a zoning regulation about having a car body without an engine in it sitting in your front yard. I could probably swing buying a chassis, but an engine is likely beyond the budget of an academic.

surfin' safari

Many people might not be aware that Mark Twain (a.k.a. Samuel Clemens), beloved author of Tom Sawyer and The Adventures of Huckleberry Finn, was an admirer of surfing, or, as he called it in his essay, Roughing It, "surf-bathing." He admired it enough to try his own hand at it, with predictable results:

"I tried surf-bathing once, but made a failure of it. I got the board placed right, and at the right moment, too; but missed the connection myself. The board struck the shore in three-quarters of a second, without any cargo, and I struck the bottom about the same time with a couple of barrels of water in me. None but the natives ever master the art of surf-bathing thoroughly."

I can empathize with Twain's wipe-out, having done something similar more than once on my very first attempt at surfing, during a recent (mid-December) trip to Kona, Hawaii. Technically, I was there doing book-related research -- research, I tell you! Authors must suffer for their art! -- by visiting the infrasound laboratory of Milton Garces (a.k.a., "the volcano whisperer"), an acoustician with the University of Hawaii whose work has been featured previously at the cocktail party -- and also in more mainstream media outlets like Wired magazine and a segment on Wired Science. (If you're not watching the show, why not? Until the writer's strike is over, everything else is reruns and reality shows. A fine time to catch up on all that quality science programming! Like the two-part NOVA series on Absolute Zero -- Part 2 airs tonight.)

One year later, I found myself driving down the Queen K Highway in my cheap little rental car to check out the lab, which is located right on the water. I'd previously only visited Honolulu, which didn't leave the best impression of our 50th state; it kinda reminded me of a super-mall in Los Angeles, to be honest, only more humid -- granted, I didn't venture very far afield from the downtown area. But Kona is the panoramic Hawaii of Captain Cook and all those surf movies (Endless Summer, Step Into Liquid, and the more soap-opera-like Blue Crush, just to name those I've actually seen). Plus it has volcanoes and fascinating microclimates, making it the perfect location for Garces' varied research, which spans not just volcanoes and breaking ocean waves, but also nuclear monitoring and (the latest twist) passively listening to the whale populations off the shore. Yes, all of those involve some kind of infrasound. The lab also has a killer sound system, capable of taking the roof off that sucka, and had the biggest speaker in the system not been out for repairs, I might have been privy to a demonstration of its acoustic power. Let's just say that Garces and his colleagues would appreciate today's XKCD:

So, I loved the Big Island. Sure, Maui has miles of sandy white beaches, while Kona's shore's are strewn with lava rocks (the entire island is basically the remnants of volcanic eruptions over thousands of years). Personally, I loved the lava rocks, as well as the local version of graffiti (placing white shells against the black rocks to make pictures and spell out the usual graffiti messages). It gives rise to some interesting geological formations. I scrambled over slick lava rocks with Garces to check out one of the island's many "lava tubes" -- the one nearest the lab is awesome, since it routinely gets hammered by the incoming waves, with the occasional shock/explosion propelling water up through the rock to the surface. It's like a geyser, only less predictable.

I also jolted along unpaved "roads" (I use the term loosely, since at one point it was little more than a grassy foot path) to the top of the mountain in Garces' (mercifully) 4-wheel drive vehicle to check out the sensor arrays that form the heart of his infrasound research. Thanks to a recent tropical storm, we ended up walking the last bit of the way. You know someone's doing hard-core field research when you find yourself longing for a machete to hack your way through the undergrowth. (And why, oh why, did I not have the foresight to bring my Tevas, which are perfect sandals for hiking and scrambling over rocks?) Anyway, then Garces insisted on taking me surfing, which pretty much makes him the best host ever -- no other lab I've visited has taken me surfing; that sets the bar pretty high.

There was actually a very good reason for doing so, apart from the fun factor, and the fact that Garces, his wife and daughter, and most of the guys in his lab, are all avid surfers, it being almost a way of life in Hawaii. I haven't been around that many tanned, uber-fit people since my last foray into Santa Monica (except in Hawaii, people look less plastic, because there's less of an obsession with steroids and silicone). Garces insisted that I could observe everything I needed to know about wavefronts by hopping on a surfboard and experiencing the ocean firsthand from that (rather vulnerable) vantage point.

And that's how my pasty-white, city-dwelling self ended up on a borrowed surfboard, gamely paddling out to meet the incoming waves. (I did not, alas, remain pasty-white; by the end of the afternoon, my entire back was bright red, even the soles of my feet. I looked like a haddock that had only been seared on one side. The Spousal Unit, always supportive, suggested when I called that I burn my front side the following day to even things out. Jen-Luc Piquant suspects he may have been a wee bit envious that his research, on the origins of the universe, doesn't call for trips to Hawaii.)

It shouldn't come as a shock to anyone that there's a lot of physics involved in surfing, so you'd think that my grasp of the basic principles, combined with my general fitness, strong swimming skills, and years of martial arts training, would give me a tiny bit of an advantage. And maybe those things helped a little, but  honestly? Surfing is one of those activities that's pretty straightforward in concept, yet very difficult to master -- as Twain found out a century or more ago. Basically, you paddle a decent way out from shore -- being careful to avoid proximity to dangerous rock formations and such -- turn the board around, and wait for a promising wave. (Jen-Luc helpfully points out that at this point, the primary physical mechanisms at work are our friends, gravity and buoyancy. Think Archimedes and his "Eureka!" moment. There is no acceleration, and thus no net force. So it's a pleasant sensation, but hardly exhilarating.) Per the Exploratorium's exhibit on the physics of surfing, you want "a nice roller, moving towards you at a constant speed." Okay then.

This is not an easy call to make; ocean wave dynamics are pretty complex. That's why surf forecasters prefer to rely on real-time meteorological data from satellites to locate the biggest waves. The size and shape of ocean waves depends on three major variables: wind speed, the "fetch" (not as in "That is so fetch!" from Mean Girls, but as in, the distance of open water the wind has been blowing over to form the waves), and how long the wind has been blowing over a given area. The best waves, according to hard-core surfers, are those produced by intense distant storms that generate heavy winds. Those winds blow continuously for several days, creating lots of waves that slam into each other repeatedly to create a "chop." Gradually, all the little waves accumulate into a larger swell. By the time they reach the shores of Hawaii (in this instance), they've become a series of power, large swells.

It was not a big wave day when I had my outing -- good news for me, as a beginner, since the waves were smaller and the waters less crowded with hard-core surfers. Generally, waves are measured according to height (from trough to crest), wavelength (from crest to crest) and period (the interval between the arrival of consecutive crests at a fixed point). Many of them eventually "break" as they move into shallower water (or when two wave systems collide and combine their forces), which is what happens when the wave base can no longer support its top, causing it to collapse. We had the pleasant spilling or rolling version of breaking waves. The plunging variety can break too suddenly, dumping surfers and pushing them to the bottom with a lot more force than one might think. There's a lot of energy in those ocean waves: depending on the size, it can be as much as 5 to 10 tons per square yard. Ouch! Surging waves might not even break, but their powerful undertows can drag unwary swimmers and surfers into deeper, more dangerous waters.

No doubt people who surf a lot, or who study wave dynamics for a living, get pretty adept at eyeballing the incoming waves to identify the most promising for surf purposes (by size, by when they're likely to break, etc) -- and also estimating how fast those waves will be traveling by the time they reach the surfer. But to a novice like me, they all look about the same, and it's tough to predict when they'll crest and break unless you have a lot of experience with ocean wave behavior. I don't, so pretty much relied on the Garces family to let me know when it was time to paddle like crazy. (They were both on hand, tanned and fit and looking perfectly at ease on their much more advanced boards.) Because you've got to get up to the same speed as the incoming wave if you want to catch it, otherwise it just shoots right past you, leaving you bobbing forlornly behind on your surfboard. That was Twain's mistake, I think. 

Or maybe Twain caught the wave, but failed to keep paddling after that first tug. That's Step 2: keep paddling until you're sure you're riding the wave, at which point you attempt to stand. And this, my friends, is where things get tricky, because a moving wave is literally a slippery slope, with constantly shifting  changing forces acting on the surfboard -- not just gravity and buoyancy at this point, but also hydrodynamics forces (exerted by a moving fluid) that push the board forward (along with a certain amount of friction or drag along the bottom of the board). Ergo, you've got to keep shifting your weight back and forth to stay near the board's center of mass as you ride the wave to keep the proper balance of forces (between the downward force of gravity and the upward buoyant force). When they're out of balance, the board torques, or twists. If the nose is too low, you pitch forward; if you shift too far back and the nose is too high, you lose your momentum, the board stops, and you pitch into the water.

Apparently it's easier to maintain that critical balance between opposing forces on a shorter board; the tradeoff is that it's harder to catch the initial waves. So for a beginner, like me, a long board is best, which is indeed what I was using. Garces assured me the board would "catch anything" (or would, with a better surfer wielding it); but it meant it got a bit trickier when I tried to stand up. 

Let's just say I wiped out on a regular basis and swallowed my share of salt water. I never quite got into a full stand, either; the best I could manage was a low crouch. But I have to say, it's pretty darned exhilarating even catching the baby waves and riding them into shore. I managed it maybe three times -- not a great record, compared to the high number of spills, but the successes are what you end up remembering. I'll be spending three months in Santa Barbara beginning in February, as Journalist in Residence at the Kavli Institute of Theoretical Physics. I'm told by CV's Daniel Holz that the surfing around there is pretty good -- provided you have a wet suit (Brrr! the water's cold!). Who knows? This surfing thing might become something of a habit. Maybe I'll even figure out how to turn, which is all about deliberately moving the balance between gravity and buoyancy out of alignment temporarily to exert a torque, and thus execute a turn.

After all that excitement, what, exactly, did I learn from the experience? Well, I learned that a high SPF waterproof sunscreen is pretty much de rigeur in Hawaii, and if I decide to go surfing again, I'll make sure to get the proper gear (although La Famille Garces were amazingly generous with their stuff). And I did come away with more of a firsthand, experiential grasp of wave dynamics (as opposed to mere book-larnin'). After all, from a mathematical viewpoint, it doesn't really matter much if you're talking about a sound wave, a light wave, or a water wave: you can still use many of the same equations in each case, notably, the infamous Fourier Transform devised by Jean-Baptiste Joseph Fourier. (This will be the subject of a future post at some point, when I find the time to write about it.) I wasn't able to find any historical evidence that Fourier, like Twain, tried his hand at surfing. I'm guessing late 18th century France was not so much with the surf-bathing. But if given the opportunity, I'm sure Fourier would have made an excellent surfer -- at least in theory.

run, baby, run

Shhh! Try to keep it down to a low whisper, will ya? Jen-Luc Piquant is currently lost deep somewhere in the final Harry Potter book, having waited patiently for her turn -- and somehow avoided all the online spoilers in the process, no mean feat by now. (Anyone considering trying to ruin the surprise for her should be forewarned: she is ruthless when wreaking her revenge. When you least expect it, she will emerge out of Cyberspace via your computer monitor, just like the ghoulish Samara in the horror flick The Ring, who comes oozing out of the TV to claim her victims. Better yet, she'll send Oscar the Cat, a.k.a., the Feline Harbinger of Death, to sit and stare at you expectantly with those unblinking almond eyes. Aieee!) While waiting for myself and Future Spouse to finish our respective readings, Jen-Luc perused the biology of Harry Potter (courtesy of the Biology in Science Fiction blog) and re-read Roger Highfield's entertaining The Science of Harry Potter to keep herself in that Rowling frame of mind. 

Certain skeptical types might assume that it is pointless to look for science in a children's fairy tale, but that just demonstrates an overly literal mind or limited imagination, in our humble opinion. It's all a matter of perspective; as Highfield ably demonstrates in his book, quite a bit of cutting-edge modern technology is, in its own way, quite magical -- electronic paper, for example. And just this week, Wired reported that DARPA -- described as "the Pentagon's way-out research arm" -- wants to design a software suite that can help battlefield commanders predict the future. Seriously. They're developing a "digital crystal ball" capable of foretelling how any given military mission will turn out beforehand. Professor Trelawney would be so proud. And maybe Oscar the Cat can help with the divination aspects.

There's been another Oscar in the news this week: Paralympic champion sprinter Oscar Pistorius, a.k.a. "the Blade Runner," a double-amputee since he was a baby in South Africa. Pistorius was born without fibulae in both of his legs, which were amputated halfway between his knees and ankles just before his first birthday. He's always worn prosthetics, taking his first steps on fiberglass pegs, and has always been highly athletic, playing rugby, water polo, tennis, even wrestling before taking up track and field after suffering a serious injury in rugby. He's known for refusing special treatment, even perfectly legal ones, like handicapped parking spaces. He says his motto has always been, "You're not disabled by the disabilities you have, you are able by the abilities you have."

[UPDATE: There's a fascinating post up at my new favorite blog, Neurophilosophy, on the discovery of the 300o-year-old prosthetic foot. Check it out!]

That motto has served him well thus far. Not yet 21, Pistorius has racked up an impressive string of titles, and is the current Paralympic double amputee world record holder in the 100, 200 and 400 meter events. A few weeks ago, he made his international debut against the world's top able-bodied runners by running the 400 meter event at the Norwich Union British Grand Prix in Sheffield, England. He didn't fare very well, given wet conditions; he placed seventh in a field of eight, and was ultimately disqualified for running outside his lane.

Now Pistorius has set his sights on qualifying for the 2008 Summer Olympics in Beijing -- and therein lies the controversy. It's not unprecedented: according to a May 15 article in the New York Times, there have been at least three disabled athletes who have competed in the Summer Olympics: an American gymnast with a wooden leg (George Eyser); a paraplegic archer from New Zealand (Neroli Fairhall); and a legally blind American runner (Marla Runyon, who competed in the 1500 meters at the 2000 Summer Olympics in Sidney). There's never been an amputee competing in an Olympic track and field event; Pistorius wants to be the first.

The sticking point is whether his prosthetics give him an "unfair advantage" over able-bodied athletes. "But the man is a double amputee!" you may well exclaim. I certainly did. Nonetheless, that's the gist of objections, and the International Association of Athletics Federation (IAAF) is still mulling over the issue before deciding whether or not Pistorius can compete. (There's very little question of his qualifying.) They throw around a lot of impressive scientific jargon when discussing his case, talking about measuring the maximum amount of oxygen his body uses in one minute, per kilogram of body weight (known as an athlete's VO2 max), or assessing the mechanical efficiency of his stride using a dizzying array of different techniques, including force plates and 3D kinematics. They've already used high-definition cameras to film his running motion.

Just what's so special about those prosthetics? These days, Pistorius runs on a pair of high-tech prosthetic limbs made out of carbon graphite, called Cheetahs, since the J-shaped design mimics an actual cheetah foot. They make a telltale "snick-snick-snick" sound on the asphalt as he runs -- a sound competitors have come to dread; one fellow runner said he felt like he was "being chased by a giant pair of scissors."  They're also a bit longer than natural limbs, which some believe enable him to cover more ground with every stride -- those naysayers include single-amputee Paralympic athletes Marlon Shirley and Brian Frasure, both of whom were beaten by Pistorius this past May at the Paralympic competition in Athens. (Jen-Luc thinks this sounds a bit like a case of sour grapes.) That's not something Pistorius can help: the Cheetahs must be longer than biological legs, to compensate for their imperfect biomechanics. Also, the design means Pistorius runs pretty much on tiptoe.

In fact, the more I read about the objections, the more it sounds like people are basing their objections on perception rather than solid science. Any cited perceived advantage is easily outweighed by everything else that Pistorius must overcome. The Cheetahs are not without their drawbacks. For instance, Pistorius doesn't experience the lactic acid buildup that plagues able-bodied athletes, but they don't have to contend with the possibility that the carbon in an artificial limb will snap at an inopportune moment, sending Pistorius to the ground in a movement that more closely resembles a skier wiping out on the slope than a runner stumbling.

He's a slow starter, since he needs to exert more energy to get moving out of the starting blocks that his able-bodied competitors; unlike them, his later stage of a race is his strongest and fastest. For that reason, he'll never be as strong in the shorter 100-meter event; he really shines in the longer 400-meter event, because there he has time to find his rhythm after the inevitable shaky start. As the Sheffield competition made clear, if it's raining, he has trouble with traction. And a stiff, strong wind can blow his legs sideways. Most runners lose speed coming out of a turn, but Pistorius might actually gain energy -- the downside is that once the Cheetahs get going, they can be really tough to control.

Most damning of all is what you find when you crunch the numbers of energy return for Pistorius' artificial limbs. The Cheetahs rely on a passive spring to absorb energy as the foot lands, returning energy to propel the next step forward -- pretty much the same biomechanical concept behind how an able-bodied person walks. but the Cheetahs can't generate anywhere near the propelling force of a biological limb: landing on a human foot in a running stride has a 241% energy return, thanks to the contraction of leg muscles, compared to a roughly 82% spring efficiency for a passive prosthetic foot like that on the Cheetahs. So Pistorius actually has to work at least 30% harder than his  able-bodied competitors to compensate for not having the usual collection of muscles, tendons, ligaments, joints and bones -- and all that power must come from his hips, producing a weird, slightly waddling stride as he runs. The field of prosthetics hasn't yet come close to matching Mother Nature's design.

Pistorius has plenty of supporters, not just detractors. Hugh Herr, director of MIT's Biomechatronics Group and himself a double amputee, thinks Pistorius has "a distinct disadvantage" in track and field: "He's just really fast." Robert Gailey, an associate professor in the University of Miami's department of physical therapy, agrees with that assessment: "There is no science that he has an advantage, only that he is competing at a disadvantage," he told the New York Times. Imagine running on stilts: that's essentially what Pistorius is doing. He's just really, really good at it because he's been walking and running on stilts since birth. His handlers are fond of saying that anyone who thinks having carbon-fiber legs will automatically make them a faster sprinter, should have the operation and meet them at the track.

True, he does have an innate advantage over Shirley and Frasure, both of whom still have one natural leg. Mixed leg sprinters aren't as smooth or fast, according to Gailey, because they lose energy to vertical movement by pistoning up and down. Pistorius might waddle a little, "but his gait has a circular smoothness." Short of amputating their other legs, Shirley and Frasure will just have to accept this innate shortcoming, or find some other means of compensation.

Pistorius isn't some futuristic cyborg, just a gifted runner with two artificial limbs. It's easy to confuse the passive prosthetic limbs used by Pistorius with more active models using bionics and robotics. For instance, Herr has developed a computer-controlled robotic ankle giving an amputee a faster and more natural gait, as well as the Rheo Knee, which has a microprocessor and numerous sensors to allow it to adapt to changes in speed, load, and uneven terrain. The motor generates extra power if the user is walking uphill, while downhill, the ankle uses a brake-like device to dissipate some of the energy. The robotic ankle is powered by a rechargeable battery capable of storing sufficient power for a walk of several miles. Similar work on an artificial foot and ankle that can adapt to changing terrains and walking speeds is being done at Northwestern University. (At the very cutting edge is Cyberkinetics in Massachusetts, which implanted 100 electrodes onto the motor cortex of a paralyzed man that enables him to operate a computer or move an artificial arm using just his thoughts. Yikes!)

Despite all the technological bells and whistles, such devices still aren't as strong or powerful as natural limbs, and they don't respond automatically to signals from the brain, because they aren't linked directly to the central nervous system. But someday they might be. In so, then those types of prosthetics conceivably could confer an unfair advantage on a disabled athlete in the not-too-distant, according to Gailey -- which might be why the IAAF is concerned about setting a future precedent. Nobody wants to see track and field turn into the massive global embarrassment that has become this summer's scandal-plagued Tour de France. "If there are no constraints placed on what technology can be used, at some point there will be an advantage," Herr admitted to the New York Times; in fact, that's the ultimate goal of such research.

Pistorius' success is pushing hard against the traditional boundaries separating disabled and able-bodied athletics, and it's raising a lot of questions and making a lot of people uncomfortable in the process. Nor is the issue likely to go away: a single amputee named Jeff Skiba competed in the US indoor track and field championships last year. The IAAF recently amended its competition rules to ban the use of "any technical device that incorporates springs, wheels, or any other element that provides a user with an advantage over an athlete not using such a device." They claim this is not intended to target Pistorius, merely to better define what constitutes therapy versus an enhancement.

Even the head of the organization's medical and anti-doping commission, Juan Manuel Alonso, admitted to the New York Times that "There is no real grounds to say he [Pistorius] should not be allowed to compete" in the Olympics. I say, enough already. Let the man compete. He's had to overcome enough. Don't make him a poster boy for futuristic technology he's not even using. Yet.

ADDENDUM: Cocktail Party Physics will be hosting the next Philosophia Naturalis blog carnival, slated for April August 15th. Jen-Luc Piquant expects to be finished with Harry Potter any moment now, and is quite keen to begin sifting through submissions. So if you've got anything, be sure to send it along to her at [email protected].