The Search for Extra Terrestrial Intelligence, or SETI, has made a business of looking for signs of intelligence in the universe. Recent data from a team of astronomers at UC Santa Cruz and the Carnegie Institute for Science have given SETI a promising place to focus their attention: Gliese-581 g, a planet 20 light-years away, in the ‘habitable zone’ around the red dwarf star Gliese-581. Many factors determine whether a planet is habitable or not, ranging from the obvious variables, such as distance to the star and the star’s luminosity, to the less obvious variables, such as whether or not the planet has a large enough moon to keep its rotation stable or a giant neighbor (such as Jupiter) to sweep away dangerous incoming asteroids.
This discovery, made with the help of the new Kepler spacecraft, suggests that Gliese-581g may have the right conditions for liquid water, considered by many exobiologists (or astrobiologists: those who theorize about extra-terrestrial life) to be essential for life.
However, some have argued that since it’s not life but intelligence that we’re really after, the habitable zone may be the wrong place to look. Seth Shostak, an astronomer at SETI, argues in a forthcoming paper that we should be looking not for biological intelligence, but artificial intelligence. According to a physorg interview of Shostak by Shaun McCormick, “Once any society invents the technology that could put them in touch with the cosmos, they are at most only a few hundred years away from changing their own paradigm of sentience to artificial intelligence,” he says. Because artificial sentience would almost inevitably outlast and outperform its fleshy, needy predecessors, Shostak concludes that any aliens we detect will be machines. ET machines would be infinitely more intelligent and durable than the biological intelligence that invented them. Intelligent machines would in a sense be immortal, or at least indefinitely repairable, and would not need to exist in the biologically hospitable “Goldilocks Zone” most SETI searches focus on.”
In other words, as soon as a biological species is advanced enough to contact us from across the galaxy, they are only a few centuries away from creating intelligent machines that will evolve and last for many millennia. Furthermore, intelligent machines will have needs and abilities quite different from their biological creators, so a habitable zone for one may not look anything like a habitable zone for the other. Thus, if SETI is to maximize its chances for finding extra-terrestrial intelligence, it may need to redirect its search.
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