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August 10, 2009 | by  | in Opinion |
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Is there anybody out there?

science

In 1950 Enrico Fermi got a paradox named after him. Fermi’s paradox asks the same question that Fermi reportedly asked of his fellow physicists who were arguing that there must be life in our galaxy besides that found on Earth: “So, where is everybody?”

Just over a decade later, Frank Drake got an equation named after him. Drake (the astronomer and astrophysicist, not the Marvel character) organised the first Search for Extra-Terrestrial Intelligence (SETI), conference and proposed an equation to estimate the number of intelligent civilisations capable of communicating with us in the Milky Way. According to the Drake equation, the “everybody” whose whereabouts Fermi enquired number between one and one million civilisations.

The aforementioned SETI conference metamorphosed through several incarnations since its inception in 1961. SETI’s search was largely based around scanning space for narrow bandwidth radio signals (which are not known to be caused naturally, so would suggest the existence of extraterrestrial technology) using huge radio telescopes, and, to a lesser degree, sending messages for SETI’s ET counterpart to pick up.

NASA and the University of California at Berkeley were early funders of SETI projects in the 1970s, as was Harvard University in the 1980s. Berkeley continues to collaborate till this day, and the US government provided financial backing for SETI again in the early 90s, but withdrew funds a couple of years later after several members of congress ridiculed the programme. SETI continued as a non-profit organisation, with the support of members around the world, many of whom converted their satellite TV dishes to aid the search. In 1999 Berkeley launched SETI@home which uses home computers to help clean up the radio signals SETI collects for analysis. You can join the search for extraterrestrial intelligence at setiathome.berkeley.edu.

Apart from one signal in 1977, notable for its unusual strength (dubbed the “Wow! signal” after the exclamation scribbled beside the circled signal on the telescope printout), SETI has yet to find a likely candidate for signals of extraterrestrial origin. Recent research has focused on finding planets that reside within a ‘Goldilocks zone’: a region of space favourable for life like that which has evolved on Earth.

In March this year NASA launched the Kepler Space Telescope to search a small part of our galaxy within 3000 light years of Earth for other Earth-like planets. Such planets would seem to be likely candidates for intelligent life in our galaxy (After all, relatively intelligent life evolved here, right?)

According to Dr Alan Boss of the Carnegie Institution of Science there are billions (up to one hundred billion) Earth-like planets in the Milky Way alone. Dr Boss told this year’s meeting of the American Association for the Advancement of Science that not only were they probably habitable, they were probably inhabited—but probably with something similar to what was on Earth three to four billion years ago. That is, bacteria.

In fact, in the 1980s astrophysicist Brandon Carter combined the time-scales of the life-cycle of a star and the time it takes for intelligent life to evolve as it did on Earth and concluded that most stars aren’t around long enough for intelligent life to evolve.

This year, however, University of Belgrade researchers led by Milan ćirković published a paper in the journal Astrobiology in which they argue that life needn’t necessarily evolve to the same schedule as it did on Earth—and that life could evolve much quicker if it evolved in a way predicted by the theory of punctuated equilibrium.

But if there is intelligent life out there, we might end up again at the problem of communication: in 2007 Rasmus Bjork of the Niels Bohr Institute in Copenhagen, Denmark, calculated how long it would take eight probes, each capable of launching eight sub-probes, to explore one region of space containing 40,000 stars: 100,000 years according to Bjork’s calculations. And it gets worse: to explore 260,000 regions in the Milky Way’s habitable zone (representing just 0.4 per cent of our galaxy’s stars) would take 10 billion years.

But Bjork says this could be sped up by restricting our focus to just those stars likely to have habitable, Earth-like planets. New Scientist magazine reported that Bjork is “cautiously optimistic” about listening out for aliens with radio telescopes—which is just the technology that SETI uses in its search for intelligent extraterrestrial life.

Join the search for extraterrestrial intelligence at setiathome.berkeley.edu
Read about the Kepler Space Telescope on NASA’s website: kepler.nasa.gov

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