Is anyone out there?
Last month, as the New Horizons space probe was beaming the first-ever images of Pluto, Stephen Hawking and Yuri Milner, the Russian billionaire and philanthropist, announced a US $100 million initiative dubbed ‘Breakthrough Listen’ to seek extraterrestrial (ET) intelligence.
The idea that we may not be alone in this unimaginably vast cosmos is a tantalising and hoary one. Most ancient civilisations have flirted with this notion. The Sumerians attributed all their knowledge to amphibious aliens. Ancient Hindu and Buddhists mythmakers imagined the cosmos to be teeming with Earth-like bodies. But it was the ancient Greek philosophers who forged ET worlds in the crucible of reason, shorn of any mythological baggage. Democritus, who gave us the atomic theory of matter, taught that space was infinite and that it was dotted with countless worlds. However, Plato and Aristotle, the high priests of Greek philosophy, were averse to the idea of multiple worlds. Unfortunately for xenology, the Catholic Church made Aristotle its patron philosopher and enshrined his Earth-centric cosmology as gospel truth.
For the next 1,800 years, the ET idea went underground. It was kept alive by a few bold heretics, such as the Italian friar and mathematician Giordano Bruno, who was burnt at the stake in 1600 for going against Church doctrine. The advent of astronomy and the Copernican revolution gave ET a new lease of life. For the next three centuries, the idea inspired an assortment of artists, writers and, scientists to fashion plausible fictions about ET worlds.
Despite its currency, however, it had remained just that, a fiction. The turning point came in 1959, when Nature published a paper by two Cornell University physicists, Giuseppe Cocconi and Philip Morrison, in which they suggested that we should start looking for signals that may have been radioed by aliens. The idea sounded quixotic, but their plea was that “if we never search, the probability of success is zero”. The paper inspired radio astronomer Francis Drake to look for ET radio signals. His endeavour resulted in what is now popularly known as the <g data-gr-id="75">seti</g> (search for extraterrestrial intelligence) project, which for the last 50 years has been scanning the skies for some sign of alien intelligence.
However, the truth is that there is no sign of them yet. Does that mean there are no aliens? In 1950, much before SETI took off, Italian physicist Enrico Fermi had posed the same question as “where is everybody?” His point was that if the universe is as old and as large as we believe it is, then it should be teeming with intelligent civilisations like ours, and, more importantly, that at least one of them should have spied on us by now. Known as the Fermi Paradox, it has persuaded some about the improbability of alien life. Stephen Webb in his book “Where is Everybody?” describes 50 other explanations. One of them is that we haven’t looked hard enough and long enough.
Not surprisingly, SETI apologists favour this interpretation. So far, the search has covered only a few thousand stars within 100 light years or so, which is not even a minuscule fraction of the Milky Way’s expanse! Besides, SETI enthusiasts argue, the power of the scanning apparatus is doubling every year or two, almost like Moore’s law for computers. Starved of funds for long (the US government stopped funding for SETI in the early 1990s), the Hawking-Milner initiative has come as a shot in the arm of <g data-gr-id="76">seti</g>.
Auspiciously enough, just a few days after their announcement, Nasa’s Kepler Mission confirmed that it had discovered the first Earth-like cousin around a sun-like star. Curiously, a couple of days later, another study put down the improbable evolution of life on Earth to sheer serendipity, almost equating it to a miracle, which, of course, is anathema for SETI aficionados. As Arthur C Clarke put it, “Sometimes I think we’re alone in the universe, and sometimes I think we’re not. In either case, the idea is quite staggering.” DOWN TO EARTH