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.