The Humans with Super-Human Vision

Originally published in Discover Magazine, July-August 2012

An average human, utterly unremarkable in every way, can 
perceive a million different colors. Vermilion, puce, cerulean, periwinkle, chartreuse—we have thousands of words for them, but mere language can never capture our extraordinary range of hues. Our powers of color vision derive from cells in our eyes called cones, three types in all, each triggered by different wavelengths of light. Every moment our eyes are open, those three flavors of cone fire off messages to the brain. The brain then combines the signals to produce the sensation we call color.

Vision is complex, but the calculus of color is strangely simple: Each cone confers the ability to distinguish around a hundred shades, so the total number of combinations is at least 1003, or a million. Take one cone away—go from being what scientists call a trichromat to a dichromat—and the number of possible combinations drops a factor of 100, to 10,000. Almost all other mammals, including dogs and New World monkeys, are dichromats. The richness of the world we see is rivaled only by that of birds and some insects, which also perceive the ultraviolet part of the spectrum.

Researchers suspect, though, that some people see even more. Living among us are people with four cones, who might experience a range of colors invisible to the rest. It’s possible these so-called tetrachromats see a hundred million colors, with each familiar hue fracturing into a hundred more subtle shades for which there are no names, no paint swatches. And because perceiving color is a personal experience, they would have no way of knowing they see far beyond what we consider the limits of human vision.

Over the course of two decades, Newcastle University neuroscientist Gabriele Jordan and her colleagues have been searching for people endowed with this super-vision. Two years ago, Jordan finally found one. A doctor living in northern England, referred to only as cDa29 in the literature, is the first tetrachromat known to science. She is almost surely not the last.

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The Mystery of the Purring Elephant

Originally published at TIME.com, August 3, 2012

Stand near an elephant herd, and you may feel a strange vibration in your chest. That’s not your heart beating in terror because you’re, well, standing next to an elephant herd. Or at least that’s not all it is. It’s also a sign that the elephants are talking to one another. Elephants are famous for their trumpeting, of course, but they also produce rumbles pitched so low that humans can’t hear them, only feel them as a sort of physical buzzing. Exactly how elephants do this has been a mystery — and while solving that mystery is not of first-order importance in understanding and preserving this largest of land animals, it would add new insight into how a whole range of species vocalize.

The best way to answer the question of elephant-talk would be to examine the animal’s larynx. Live elephants are notoriously touchy, and recently deceased elephants are hard to come by. So when a team of University of Vienna biologists who study animal sounds heard that an elderly zoo elephant in Berlin had died, they wasted no time requesting the larynx, which was soon on its way to Vienna on a bed of ice. What they did with it next is the focus of a paper in this week’s Science.

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Three Little Exoplanets, All in a Row

Originally published at TIME.com, July 27, 2012

In a universe that exists in at least three dimensions and perhaps many more, our solar system remains an oddly 2-D place. At the center sits the Sun, with the eight planets spinning around it in a tidy plane, parallel to the solar equator. This is a function of the way the planets swirled into existence from the same cloud of dust and gas that gave rise to the sun itself — and is one of the things that got poor Pluto booted from the planet club altogether back in 2006. The ex-ninth planet travels in a steeply inclined orbit, rising above and diving below the solar plane — a clear indication that it’s merely an escapee from the vast belt of comet-like objects that circle the solar system.

When astronomers began discovering exoplanets — worlds orbiting other stars — they expected those solar systems to follow the local model. But that’s not how things turned out. Planet after planet that was spotted in the earlier days of the search, when all we could detect were very large planets circling very bright stars, were not lined up the way they were supposed to be. Instead, these Jupiter-like gas giants hang at a cock-eyed angle, and sometimes rotate backwards or orbit in the opposite direction of the star’s own spin.

Finally, astronomers studying a star known as Kepler-30 have found something that looks reassuringly familiar: one, two, three exoplanets, orbiting in a plane, just like we do. And as reported in the current issue of Nature, it’s not only the discovery itself that’s cool, it’s the way the researchers went about making it.

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Running on Physics: Why You Can Run on Water and Cornstarch

Originally published at TIME.com, July 18, 2012.

Cornstarch and water have launched a thousand geeky pool parties. Stirred together in roughly equal proportions, they form a fluid that turns miraculously solid for a fraction of a second wherever it’s struck. This means, as numerous YouTube clips attest, that you can run across the surface of a wading pool filled with the gooey mix without sinking. As long as you keep up your speed, stepping stones sprout out of the fluid and bear your weight.

Why the stuff does this is a puzzle. Scientists have usually studied it by pouring a teaspoonful on a metal plate, sliding another plate across the surface, and recording how the fluid pushes back. But that presents a problem: when you run across a pool of the fluid, after all, you don’t slide on it, you stomp on it. Now the mystery — on which profound science admittedly does not turn but cool science definitely does — may at last have been solved by Scott Waitukaitis, a graduate student in physics at University of Chicago, whose work was just published in no less a venue than last week’s issue of Nature.

Waitukaitis began his research by talking the problem over with his adviser, physics professor Heinrich Jaeger, with whom he crunched the numbers and concluded that the theories based on the teaspoon experiments were nowhere near explaining how the fluid could support the weight of a human being. Mulling this, Waitukaitis devised his own experiment, which at first involved spending a lot of time throwing balls into buckets of cornstarch and water. After several disastrous attempts to mix a large batch of the material by hand — “It’s incredible,” he says, “how easy it is to get a shovel stuck in this and not be able to get it out.” — he started using a small cement mixer and, to protect his clothes, took to wearing a blue jumpsuit around the lab. His previous work went on hold as he developed more and more elaborate ways to measure the movement of the fluid, culminating in a series of experiments in which the tip of an aluminum rod, dropped from above, slammed into about 7 gallons of cornstarch and water. A battery of instruments then watched what happened.

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The Mystery of the Disappearing Stardust

Originally published at TIME.com, July 11, 2012

Stars wrapped in warm, dusty disks sound cozy, and in cosmic terms, they are. They are the incubators in which planets like our own — rocky, and fairly close to their parent sun — are most likely to form. In these disks, dust is coalescing and tiny chunks of rock are colliding to become larger masses of matter and, over the course of millions of years, planets. The theory is far from perfect, though, and computer models meant to simulate the process raise as many questions as they answer. Astronomers have lately tried to remedy that, watching dust-shrouded stars for any small changes — maybe a tiny shift in the amount of starlight making its way to Earth — that they can plug into the models to help make them fit reality.

Carl Melis, a postdoctoral fellow at the University of California, San Diego, and his collaborators chose one of the dustiest stars ever seen — one that goes by the prosaic name TYC 8241 2652 — and planned to watch it for a good long time. When the team took a look at it in May 2008, through one of the Gemini Observatory telescopes in Chile, the star appeared much as it had when it was first observed in 1983. In January 2009, they took another look. What they saw was astounding.

Nearly all the dust had disappeared.

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Literary Nonfiction: Sharp Things

Written in 2007 for Anne Fadiman’s “At Home in America” seminar.

On Thanksgiving Day 2002, my family broke into a quarry near Lee Vining, Calif., and carried away several pounds of rocks in three paper bags. It wasn’t much of a burglary, as burglaries go — we parked our minivan on a deserted road in a lodgepole forest and climbed over the steel gate without any employees bothering us. They were all home in June Lake, the last hamlet before Mammoth, to the south, or in Mono City, a string of thirty mobile homes on Lundy Creek. We were staying in Mono City too, in the thin-walled double-wide of a friend who wasn’t around, and we spent a great deal of time outside.

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Literary Nonfiction: The Way of Curds

Written in 2007 for Anne Fadiman’s “At Home in America” seminar.

From the door, the interior of the whole building is visible: a gargantuan stove, a dairy-style floor drain, a steel vat, and an unusually large number of industrial garbage cans on wheels. Five cans stand by the entrance, lids sealed tight; one can stands in the corner with its lid off, allowing a black hose to trickle water over the rim. The floor is slick with the can’s overflow, and a sour, light-green smell hangs in the air, tinged with ginger and soy sauce. On the red cement floor, three buckets cluster around a device that bears a disturbing resemblance to a wood-chipper, and on the yellowed wall, a price list hangs: “unchicken, unturkey sandwiches: $3.50 each.” Over in the can in the corner, waiting, is a treasure trove of little golden beans, each the size of a fingernail and greedily absorbing water.

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Update: I’m now writing at DiscoverMagazine.com

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