Energy Forum / Alternative Energy

Luis von Ahn
Computer Scientist, Carnegie Mellon University

Luis von Ahn, 30, has left his mark all over the Internet. When you buy tickets online and are asked to decipher an image of distorted words—that’s the work of von Ahn. He helped develop this antispamming technology, known as CAPTCHA (Completely Automated Public Turing Test to Tell Computers and Humans Apart), in 2000. CAPTCHA works because it is solvable by man but not by machine. Still, von Ahn’s ultimate goal is not to outwit computers; instead, he wants to exploit man’s unique intelligence to eliminate the machine’s shortcomings—while completing some useful tasks along the way.

One vehicle to close such an intelligence gap is reCAPTCHA. Each day it utilizes about 18 million computer users—perhaps ticket buyers—to key in words from scanned pages of text in order to digitize them, words that a computer is not yet able to recognize. (By next year researchers expect to finish digitizing The New York Times archive dating back to the 1850s.) Von Ahn also programs games with a purpose: The more you play, the more data you provide toward helping computers recognize images. “I don’t think we’ve even scratched the surface of what we can do,” he says. —A. G.

Tapio Schneider
Environmental Scientist, Caltech

The complex interactions of atmospheric turbulence and heat transport affect global climate. Tapio Schneider, 36, has developed computer simulations to better understand how. “Ideally, I’d like to build myself a climate in a laboratory,” he says, “but we can’t do that with a planet, so computers are the next best thing.”

In a developing project, he recently used a model planet to show that monsoons can form even in shallow water like a swamp. Therefore Halley’s traditional model for monsoons—that the different heat capacities of land and ocean surfaces cause these seasonal deluges—doesn’t give a full picture. The movement of water vapor through climate systems remains poorly understood, Schneider says. “That’s one set of questions that I will be working on for many years.”

Schneider’s goal is to build a set of fundamental laws of physics for climate. “The laws of thermodynamics give a macro­scopic description of microscopic behavior,” he says. “I would like to have something analogous for climate.” —S. W.

Astrophysicist Sara Seager is looking
for signs of distant life.
Photo: Len Rubenstein

Sara Seager
Astrophysicist, Massachusetts Institute of Technology

As questions swirled around the existence of extrasolar planets in the late 1990s, Sara Seager, 36, gambled that these distant flickers transiting in front of stars would grow into astronomy’s next frontier. The bet paid off: Her theoretical models of the chemistry of extrasolar planets have helped researchers make the first atmospheric measurements of a distant world. Seager expects that we’ll find a cousin to Earth in the next couple of years, but her ultimate goals are grander. “What I really want to do is figure out which kinds of gases extraterrestrial life might produce,” she says. “These gases would accumulate in the atmosphere and might be detectable from afar.” As a step in that direction, she’s looking for signatures, other than oxygen-based ones, that Earth-like life might leave behind, such as hydrogen sulfide.

During Seager’s childhood in Canada, her father exposed her to a variety of ideas—including that of a stargazing party. “Having that time to daydream,” she says, “was so crucial to making me a good scientist.” —S. W.

Jon Kleinberg
Computer Scientist, Cornell University

In the mid-1990s a Web search for, say, “DISCOVER magazine” meant wading through thousands of results presented in a very imperfect order. Then, in 1996, 24-year-old Jon Kleinberg developed an algorithm that revolutionized Web search. That is why today, that same search lists this magazine’s home page first. Kleinberg, now 37, created the Hyperlink-Induced Topic Search algorithm, which estimates a Web page’s value in both authority (quality of content and endorsement by other pages) and hub (whether it links to good pages).

Kleinberg continues to combine computer science, data analysis, and sociological research to help create better tools that link social networking sites. He envisions an increase in how we can see information move through space over time, in what he calls geographic hot spots on the Web, based on the interests of a particular region.

Our social network links and friendships depend on these geographic hot spots, Kleinberg says, which makes searching easier by “taking into account not just who and when, but where.” He is now studying how word-of-mouth phenomena like fads and rumors flow through groups of people, hoping to apply this knowledge to processes such as political mobilization. —Julianne Pepitone

Edward Boyden
Neuroengineer, MIT Media Lab

Certain species of bacteria and algae have genes that allow them to transform light into electrical energy. Edward Boyden, 29, has been able to show that inserting one of these genes into a neuron can make it similarly responsive. “When we illuminate these cells...we can cause them to be activated,” he says.

Having created such genetically modified neurons, Boyden is engineering brain implants that can stimulate them with light pulses. Boyden’s implants, he hopes, will be used to help control diseases like Parkinson’s, which is sometimes treated with implanted stimulators that issue electric current. “There are things that light can do that purely electric stimulators can’t,” Boyden says. With this technology, researchers can be selective about which neurons they engineer to be responsive, and an optical implant can emit light in a variety of patterns, allowing more precise control over neural circuits. —E. A.

Protein structures help biologist Richard Bonneau
map how organisms work.
Image: Richard Bonneau

Richard Bonneau
Systems Biologist, New York University

Chronicling the parts of cell anatomy class-style is all well and good, says Richard Bonneau, 33, but biologists’ true holy grail is understanding how each part dictates the function of the others. “You might know that A is related to B, but if you don’t have a dynamic picture of your system, you don’t know which part is affecting which,” he says. “I want to put the arrows on the lines, so to speak.”

By tracking activity in almost all the genes of a free-living archaeon—which, like a bacterium, is a prokaryote—Bonneau was recently able to piece together how the genes affected one another’s expression, enabling him to map the organism’s “control circuit” as if it were a machine. In the process, he found something surprising: Instead of generating completely different responses to external stimuli like light and toxic chemicals, “the archaeon takes those environmental stimuli and puts them into the same integrator,” he says. “There’s not an infinite number of responses.” Knowing the limited range of behaviors that microorganisms display, he adds, will prove a big help in engineering them to churn out drugs and biofuels. —Elizabeth Svoboda

Shawn Frayne
Inventor, Humdinger Wind Energy

Shawn Frayne, 27, has a knack for creating simple technological solutions that make a difference for people in developing nations. He was part of the team that introduced sugarcane-based charcoal as a cheap cooking fuel, and his solar disinfecting plastic bags purify water for drinking.

It is his Windbelt, though, that may have the most impact. Inspired by the dynamics of the 1940 collapse of the Tacoma Narrows Bridge, Frayne spent four years developing the world’s first turbineless wind generator. When the wind blows, it causes a flap of Mylar-coated taffeta fabric to vibrate rapidly, moving magnets fitted on either end past coils to generate electricity. In the developing world, the 10 watts it produces can light a room at night by electricity rather than expensive and dangerous kerosene.

By selling intellectual property rights for his inventions to big companies, Frayne hopes to fund more innovative projects for developing nations. “That is where the biggest challenges are, and it’s where I think most of the invention and innovation are going to come from in my lifetime,” he says. “It would be crazy to work anywhere else.” —A. G.

Jonathan Pritchard
Geneticist, University of Chicago/Howard Hughes Medical Institute

It’s easy to think of evolution as something that happened millions of years ago, but Jonathan Pritchard, 37, has proved we’re actually adapting to our environment in real time. Using statistical models to home in on genetic mutations that spread quickly throughout populations, Pritchard and his colleagues have identified hundreds of regions of the genome that have recently been transformed by natural selection. “If a new mutation arose in a certain population and it was strongly favored, natural selection would drive the frequency of that allele up very quickly,” he says. “Most of the time there are only small frequency differences between human groups, so when there are big frequency differences, they really stand out.” —E. S.

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