I was a voracious reader as a child (I still am, whenever my frenetic schedule permits). I’d read anything you put in front of me, including cereal boxes, appliance manuals, and Monopoly instructions. One of my earliest memories is sitting on my father’s lap, all of four years old, trying to read his latest issue of Time, although it must be said that my comprehension of the weighty matters contained therein left a lot to be desired. I also plowed through a children’s encyclopedia collection that my parents kept in the house for our edification. My favorite was the volume on mythology; I had a particular affinity for the tragic figure of Icarus.
You remember the tale: he and his father, Daedalus, were exiled onto a deserted island. Daedalus fashioned two pairs of wings, affixed to the shoulders with wax, so they could escape their island prison by flying into the air like birds. But Icarus became so exhilarated mid-flight about defying gravity that he ignored his father’s warnings about flying too high. He flew too close to the sun. The heat melted the wax, the wings came loose, and poor Icarus plunged to his death in the waters below.
To my shy and rather timid young self, the lesson was obvious: it’s far preferable to keep one’s head down and lie low, rather than try to fly and risk crashing ignominiously to earth. It was a very long time before I overcame my innate "fear of flying" and realized that life is all about taking risks. What’s that catchphrase from the film, Strictly Ballroom? "A life lived in fear is a life half lived." At some point in my adult life, I decided that half lives are for radioactive materials, not for me. That’s one reason I was able to assume the risk of becoming a science writer and rising above a long-standing irrational fear of physics.
I was reminded of Icarus over the past few days. On Sunday, NPR’s Weekend Edition aired a short five-minute interview with me about my book, Black Bodies and Quantum Cats. As a result, I spent the day fielding calls and emails from friends — and a few long-lost acquaintances, one of whom expressed surprise that I’d ever amounted to anything — and watching my book skyrocket up Amazon’s mysterious ranking system, a phenomenon that is actually known at NPR headquarters as "the NPR Effect." (Physicists should get right on that bit of research.) By the end of the day, the story was the top emailed article on NPR’s Web site, so clearly it struck a responsive chord with the listeners. But even awash in the glow of such modest success, I couldn’t help feeling anxious and apprehensive about flying too close to the sun; Icarus lurked at the back of mind.
The inevitable crash was not long in coming. The linked page also includes a short excerpt from the book, on roller coasters and the infamous 1999 incident where male model Fabio was hit in the face by a wayward goose mid-ride. It includes an abridged explanation of the various forces at work on a roller coaster ride, including the so-called "g forces." Unfortunately, as one alert reader/listener (whom I shall call "Z") pointed out via email that evening, my summation is not quite right.
Here’s the gist of his — and it’s always a "he," for some reason — points: First, mass is not related to the number of atoms (although I’ve seen
it described as such in more than one place, so clearly a broader
correction is needed beyond my book): it’s a measure of the inertia of
a given object, that is, its tendency to stay at rest or move uniformly
in a straight line, which also determines how much force is required to
get said object moving. And g is not the "force of gravity," but
rather, the acceleration due to gravity. A roller coaster rider at 4
g’s does indeed experience a force equal to four times his weight, but it’s
his "apparent weight" that increases during acceleration, not his "actual" weight.
Oops. That sound you hear is the unmistakable "thud" of me crash-landing to earth. Seriously, color me embarrassed by the gaffe. One of the hardest things about writing on physics for the general public is deciding how much to simplify the intricate details. Physicists always seem to want to include too much information, and thereby lose the interest of their intended audience far too soon. I’m good at holding a reader’s attention, but sometimes — as in the present case — I play a little too fast and loose with the details, particularly when it comes to how physicists vs. the public use specific terminology. Who ya gonna please, when you can’t please both? That’s the eternal question
Now, Jen-Luc Piquant is a bit proud and hates to have her shortcomings so baldly exposed; she believes there is a special place in hell for nitpickers like this — perhaps even Dante’s dreaded Ninth Circle. But I’ve said before that I have no problem being corrected, so long as the people are nice about it, and Z. was as polite as they come; he even emailed back with a correction to his correction. I think folks like Z. should all volunteer as fact checkers at publishing houses, newspapers and magazines, where they can fully indulge their need to make corrections in the work of others, and thereby serve a useful purpose to society by ensuring such mistakes don’t see print. Because I happen to agree with Z’s statement: "Though physics terms like force, work, power, etc. may have loose meanings in everyday language, they have very precise definitions in physics." I actually take these distinctions quite seriously, and worked very hard to verify accuracy before the book was published. Despite my best efforts, tiny errors crept in, as they inevitably do; it’s an inescapable reality of publishing.
Alas, there’s not much I can do about it for the moment. Online stories
can be corrected almost immediately. Newspapers and magazines can print
corrections and retractions. Books are much more permanent. Unless
there’s a second edition (which is distinct from second or even third
print runs), the errors must stay in place, for now. But I do have a blog, and in the
interests of accuracy, let the record show that I hereby make the correction.
It’s rather fitting that gravity proved to be my downfall, considering my affinity for the legend of Icarus. It might be weak compared to the other fundamental forces, but gravity is an inescapable reality of our human existence. Scientists have to come up with all kinds of ingenious ways to work around the limitations it imposes. Take the "Prometheus Project," a research team made up entirely of undergraduate students who will be exploring how sound waves might be used to extinguish fires in low-gravity environments like the space station. They’ve already managed to repeatedly extinguish small flames in a controlled laboratory environment using sound, but it’s not clearly exactly why it works. The working hypothesis is that sound causes pressure to drop at the site of the flame, which might also involve a drop in temperature at said site, (chilling the flame) or a decrease in the concentration of oxygen (starving the flame).
In what will no doubt be the highlight of their young lives so far, the students get to test their hypothesis this summer aboard NASA’s "Weightless Wonder" C-9 aircraft, a.k.a. the "Vomit Comet" — a moniker that really bugs NASA officials, so I feel compelled to repeat it here, just to yank their chain. (Jen-Luc Piquant is seething with jealousy, since NASA rejected her
proposal to study the effects of microgravity on the cellulite of aging
celebrities as a possible alternative to liposuction. The anonymous
peer reviewer opined that celebrities already defy
gravity.) An earlier KC-135 aircraft, retired in 2000, was used to film many of the zero gravity scenes in the blockbuster film, Apollo 13. The current Weightless Wonder produces 25 seconds or so of weightlessness by flying in a roller-coaster-like path of steep climbs and free falls. (Roller coasters again — behold the tenuous connection!) Except in this case, the coaster is about 10,000 feet high. The aircraft’s dramatic, parabolic flight patterns temporarily counteract earth’s gravity, creating "weightlessness," and sometimes leading to motion sickness — hence the "vomit comet" nickname.
Cool factor aside, the students do have a scientifically valid reason for performing their experiment in such an anti-gravity environment. Conventional fire extinguishers, it turns out, don’t work properly aboard spacecraft; the foam tends to spread out in a low-g environment rather than smother the flames. It might be a good idea to figure out how best to extinguish fires in space. Although there are more terrestrial potential applications, too: the knowledge might be useful for fighting fires in computer rooms, where expensive hardware can be damaged by normal chemical extinguishers.
This past February, NASA’s microgravity school program also benefited teachers from two southern California schools. One project was called the Rotational Artificial Gravity Experiment, designed to help students determine how fast a space station would have to rotate to create artificial gravity on board. The other was the Bubble Project, aimed at achieving a better understanding of how soap bubbles behave in a microgravity environment: specifically, how long it lasts, its size and its direction of travel in reduced gravity.
It just so happens that the study of bubbles and foam is pretty cutting-edge science, and the Bubble Project isn’t the only research venture that seeks to study foam’s properties in the absence of gravity. In that infamous, riddled-with-nitpicky-errors book of mine,
there’s a chapter on foam and bubbles, in which I discuss the work of Boston University researcher Glynn Holt. (It’s based in part on an article on the physics of foam I wrote for Discover
back in 2002.) It’s actually rather difficult for sudsy scientists to
create predictive models of foam’s rheology — that is, how it deforms
and flows over time — because anything you use as a container
inevitably changes its shape and behavior. Holt got around this problem
by using sound waves to float individual drops of foam in mid air using
a technique called acoustic levitation. He can even manipulate the
suspended drop by altering the acoustic field, changing its position,
or squeezing it to cause the bubbles that make up the drop to vibrate.
Sometimes it can seem as if gravity "disappears," even on earth, as with the notorious "Gravity Hill, part of a remote local road located in south central Pennsylvania. For no cost whatsoever, the low-budget tourist can marvel as water seems to flow the wrong way, and cars seem to roll uphill. It’s just an optical illusion but it’s fun, nonetheless. The news that University of Oregon researchers have made water "climb stairs" in the laboratory isn’t an illusion — but it’s a damned clever trick, basically exploiting the same phenomenon that causes water droplets to bead up and dart around a really hot frying pan. The Oregon researchers just turned the frying pan into a very hot ratcheted staircase. (You can see a helpful diagram of the experiment here.)
For most of us, though, there are no clever tricks or illusions to offset gravity. Still, I take comfort in the fact that all the sturm und drang is by its very nature transitory. The NPR link is no longer the top emailed story on the site; it’s disappeared into the archives altogether. And after peaking at #14 on Amazon Sunday evening, my book has begun a slow, prolonged descent back into the online reader’s abyss from whence it sprang. See? No matter how high you soar, gravity always wins out in the end and brings you crashing down to earth. Icarus learned this the hard way and paid for his error with his life. I escaped with a few scratches to my ego, having learned some very useful things about the finer points of gravity and acceleration in the process. I think that’s a fair trade.
After all, one shouldn’t let one’s fear of flying keep one from strapping on a metaphorical pair of wings and testing the limits — just to see if it can be done. Far worse than having the odd error in my book, would have been not writing it at all because I was too afraid of making mistakes. So I applaud those students and teachers who brave the Vomit Comet for their daring. It’s only by pushing the limits that any kind of growth or progress can be made. Why bother with a life half lived?