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Tuesday, Nov 10, 2009
Robots with common sense
In the mid-1960s, Marvin Minsky, a founding father of the field of artificial intelligence, predicted that computers would be as smart as humans in less than a decade. Since then, computers have become exponentially more powerful and clever; they can now translate languages, recognize voices, judge loan applications, interpret cardiograms, play championship chess, help us navigate our cars. But while computers excel at performing tasks that can be precisely defined, they still lack the flexible, all-purpose intelligence -- the ordinary common sense -- that most humans acquire in childhood.
Some artificial-intelligence researchers now doubt that computers will ever display the complex, humanoid intelligence of HAL, the silicon star of Stanley Kubrick's film "2001." In the essay collection "HAL's Legacy," the computer scientist Roger Shank declares that HAL "is an unrealistic conception of an intelligent machine" and "could never exist." Computer scientists can only create machines that "know a great deal about what they are supposed to know about and miserably little about anything else." Minsky rejects that pessimism, pointing out that computers have failed to acquire common sense because scientists have failed to give it to them. "There's been only large project to do something about that," Minsky remarked recently, "that's the famous Cyc project."
The gigantic software program called Cyc is the brainchild of Douglas Lenat. Since 1984, he and a small team of co-workers have painstakingly embedded millions of common-sense rules, or assertions, into Cyc. As a result, Lenat says, Cyc "knows that trees are usually outdoors, that once people die they stay dead, and that a glass filled with milk will be right side up, not upside down." Those are the sorts of assumptions that supposedly smart computers often fail to make. Lenat calls Cyc "the world's first true artificial intelligence, having both common sense and the ability to reason with it." He believes Cyc has already achieved something akin to consciousness. "If you ask it what it is, it knows that it is a computer," he says. "If you ask who we are, it knows that we are users."
In 1994 Lenat founded Cycorp in Austin, Texas, to market commercial applications for Cyc. In an effort to tap into funds flowing from the Department of Homeland Security, Lenat has trained Cyc to be an expert in identifying security loopholes in communication networks. But Cyc's most impressive talent is gleaning the contextual rather than just literal meaning of language. As a result, Cyc can supplement speech-recognition and language-translation programs; it can also boost the power of search engines by responding to the spirit and not just the letter of requests for information.
Lenat hopes that Cyc will eventually become more or less autonomous, capable of acquiring new knowledge by prowling the Web and absorbing information on its own. After that phase transition, Lenat predicts, Cyc will begin evolving in ways that may be difficult to predict. Cyc will become a "full-fledged creative member of a group that comes up with new discoveries," Lenat says. "Surprising discoveries. Way out of boxes."
Lenat has given versions of Cyc to other computer scientists, who are free to tinker with it as they choose -- creating, in effect, children of the original Cyc, which will no doubt develop in their own idiosyncratic ways.
Perhaps Cyc and its offspring will help us solve the neural code or other problems -- that is, if they do not turn on us, like the psychopathic killer HAL.
122 years young
In 1997, a French woman named Jeanne Calment died at the age of 122, making her the longest-lived human on record. Soon, some anti-aging enthusiasts suggest, we may pity Madame Calment for dying so young. In a recent issue of the journal Gerontology, Aubrey de Grey, a computer scientist turned biogerontologist at Cambridge University, predicts that some people now in their 60s will still be alive in the year 3000.
De Grey is merely one of the more flamboyant members of a growing corps of scientists who believe we are on the verge of solving that quintessential aspect of the human condition, mortality. As the journalist Steve Hall documents in "Merchants of Immortality," the National Institutes of Health and venture capital firms such as Kleiner Perkins have poured money into research aimed at slowing down, stopping and even reversing senescence. The White House Council on Bioethics takes the prospect of immortality seriously enough to deplore it in position papers.
Over the past decade, researchers have identified myriad biological processes that contribute to aging as well as ways to extend the lifespan of simple organisms.
Early on, investigators focused on telomeres, bundles of DNA that cap the ends of chromosomes. Every time cells divide, telomeres get a little shorter, until finally cells stop dividing altogether after 50 or so divisions. Some researchers speculate that if they can prevent telomeres from shortening, they might make individual cells and even entire organisms immortal. Scientists have also discovered genes that, when manipulated, can boost the lifespan of yeast, worms and fruitflies. Genes with similar structures have been identified in humans, inspiring hopes that genetic tinkering might greatly extend human life.
Scientists have boosted the lifespan of mice and other animals by more than 50 percent simply by curtailing their diets, a method called caloric restriction. Recent investigations suggest that caloric restriction works by altering activity within mitochondria, cellular structures essential to metabolism. As mitochondria consume nutrients, they produce oxygen ions called free radicals, which in abundance wreak havoc on DNA and other crucial biological components. Free radicals are thought to cause the wear and tear of senescence as well as genetic mutations that trigger cancer and other diseases.
Some gerontologists advocate a low-calorie diet -- especially one rich in antioxidants, substances that counter the effects of free radicals -- as a way to extend life by reducing the risk of cancer, heart disease and other afflictions of age. Others have proposed countering free radicals with more exotic interventions involving modified versions of antioxidant enzymes found in bacteria. De Grey advocates an approach he calls Strategies for Engineered Negligible Senescence, or SENS, which involves attacking aging on every possible front: with genetic engineering, stem cells, telomere intervention, cloning, antioxidants and caloric restriction.
Aging, he says in a recent issue of Technology Review, "is something we need to fix," and at 42 de Grey is confident that he will live long enough to reap the benefits.
Desktop fusion reactor
For more than half a century, physicists have been trying to harness fusion -- the nuclear reaction that makes the sun and other stars shine and hydrogen bombs explode -- to create a cheap, clean, boundless source of energy. Unlike fission, which involves splitting the nuclei of heavy elements such as uranium and underpins the nuclear-power industry, fusion occurs when the nuclei of two light elements such as hydrogen fuse to form a heavier element such as helium. Unfortunately, the experimental fusion reactors built to date are gigantic, expensive, Rube Goldberg contraptions, which attempt to mimic the stupendous heat and pressure of the sun but so far consume more energy than they produce.
Physicists have long dreamed of finding a way to generate fusion with small, simple devices at or near room temperature. A method dubbed cold fusion briefly galvanized researchers more than a decade ago but turned out to be bogus. The fusion-research community is therefore thrilled by the news that physicists at the University of California at Los Angeles have built a desktop fusion reactor the size of a lunch bucket. The reactor consists of a so-called pyroelectric crystal in a chamber filled with gaseous deuterium, a variant of hydrogen containing an extra neutron. When heated, the crystal acquires an electric charge, ripping electrons off the surrounding deuterium atoms and propelling them toward a target of solid deuterium. When the gaseous and solid deuterium atoms collide they fuse -- creating helium atoms and spewing high-energy neutrons.
The remarkably low-tech UCLA device has no moving parts and does not even have to be plugged in to work. Dunking it into warm water can heat the pyroelectric crystal enough to yield some fusion.
With some refinements, the gadget could serve as a compact neutron source, which could be incorporated into implantable devices for irradiating tumors, handheld medical imagers, baggage and cargo scanners, radioactive-material detectors, propulsion systems for spacecraft, and particle accelerators for further research on fusion.
The UCLA team emphasizes that the device probably cannot produce more energy than it consumes and hence cannot serve as an energy source. But at the very least, the gadget should energize the moribund fusion-research community --which for years has been losing prestige and funding -- to seek other simple, low-cost fusion techniques that can be scaled up for large-scale energy generation.
Decades ago, fusion researchers justified their enormous budgets by promising that one day fusion would give us an energy source "too cheap to meter," freeing us of our dependence on fossil fuels and fission reactors, which require fuels that can also be used to make nuclear bombs. Obviously, we need such a breakthrough now more than ever.
