The Eerie Silence by Paul Davies

Author:Paul Davies
Language: eng
Format: epub
ISBN: 9780141944050
Publisher: Penguin Adult
Published: 2010-02-01T16:00:00+00:00

The most obvious explanation for the absence of aliens on Earth is that aliens don’t exist – that is, we are alone in the universe. That was presumably Fermi’s own position, and the point of his argument was to pooh-pooh the flying-saucer stories. If that is the correct answer, then SETI is a waste of time and money. But we mustn’t be too hasty in drawing this pessimistic conclusion. There could be any number of reasons why alien civilizations are out there, but not here. An entertaining book by Stephen Webb lists no fewer than fifty explanations for ET’s conspicuous absence,2 ranging from the ‘zoo hypothesis’ (we are being watched, but not contacted) to the ‘parallel universe’ hypothesis (the aliens are having too much fun exploring other universes to bother with us). Take your pick.

By way of illustration, consider the following resolution. Suppose there are many civilizations in the Milky Way, and they long ago established a galactic network of information exchange. This is an idea dating back to 1974, when the Stanford University astronomer Ronald Bracewell envisaged a ‘Galactic Club’ of communicating civilizations, sharing news, information and gossip, with data zipping from star to star like e-mails over a cosmic internet.3 The club might even have been established before the solar system formed, 4.5 billion years ago (the galaxy is over 12 billion years old). Some members would drop out as their civilizations faded or were destroyed by a catastrophe, others would sign up as they attained radio technology and discovered that there was a network of information exchange already operational. Bracewell regarded humanity as on the verge of joining this Galactic Club – as its newest member – a step that would bring us untold benefits, but would also serve as a strong disincentive to embark on interstellar travel. If the motivation to explore is curiosity and information-gathering, it is far easier to simply log on to the GWW (Galactic Wide Web) and obtain the information for free. It is, after all, much faster and cheaper to send radio waves across interstellar space than big metal machines. If there is somebody at the destination planet already, then why bother to make the trip? If the purpose of space travel is exploration, well, the aliens can send us the content of their latest DVD. On the other hand, if it is conquest, then the fact that the target planet already has a far more advanced civilization ensconced would constitute a pretty strong deterrent. All in all, it would make more sense for the newcomer civilization to stay put and simply join the Galactic Club. But if nobody is travelling, there is no reason why the aliens should be here, or should ever have passed this way. It doesn’t mean there isn’t anybody out there, only that space travel is not an idea with enduring appeal. I believe this argument has some force, but it is convincing only if there is a very large number of planets with indigenous technological communities.

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