As well as being a history of SETI, 'The Eerie Silence' is also a passionate defence of the organisation. To me, Paul Davies' prose carries with it an almost plea-bargaining air of hopeful self-preservation. SETI has come under a lot of fire recently; especially sceptical commentators like to label the project as being an embarrassing white elephant of the science world - after so much money and no results, what's the point? There's also the cynical and somewhat prevailing sentiment that searching for alien life is nothing more than pseudoscience; the stuff of immature sci-fi novels.
However, by far the most damaging (and popular) criticism of SETI is a kind of economic determinism, which argues that if SETI is someday successful in detecting a non-terrestrial, artificial radio transmission, there will likely be no practical, financial or economic gains from doing so. High monetary input with no monetary yield does not make for valuable investment. Concordantly, SETI has suffered from substantial funding cuts in recent years. Of course, being the liberal student of the arts that I am, I take issue with the notion that all human endeavour should be geared towards a financial end-product. Whatever happened to finding value in the journey? Or striving to achieve something not because it carries a large financial incentive, but because it's incredibly difficult and challenging? The frontier spirit, Davies argues, is intrinsic to human experience, and it's a shame that SETI, as endeavour, is no longer considered viable purely because it carries no fiscal (or in some cases military) guarantees. If the current funding trend continues, then SETI will soon be entirely dependent on benevolent private donations: hardly the stable bedrock required by long-term scientific enquiry.
Drawing the reader's attention to the many criticisms of SETI is risky business, but Paul Davies provides convincing and intelligent rebuttals to all of these. His determination to present SETI as a serious methodical pursuit rather than the imprecise hobby child of UFO obsessed sci-fi dorks is commendable, if a tad unnecessary.
Yet the article of contention with which the book is most concerned is scientific, namely: the Fermi Paradox. The paradox's namesake Enrico Fermi became famous for espousing a form of evidential scepticism about SETI: "where are they?" is how he succinctly voiced his concerns. Basically, the Fermi Paradox can be summed up thus: if the universe is so old, and so big and so full of so many trillions of stars, then why is there absolutely no evidence of alien life anywhere? (okay, so it's not technically a "paradox" - but hey, they're only scientists!). It sounds simple enough, but the Fermi Paradox has so far proven to be the foremost prodigal spanner in SETI's otherwise well-oiled works. If the universe is metaphorically teeming, then why does it seem to...empty? There are two possible explanations: either there's something fundamentally wrong with SETI's search methodologies, or we really are alone after all.
Paul Davies plumbs for the former. 'The Eerie Silence' argues that it's time to stop pinning our hopes on targeted alien radio broadcasts and to begin looking for any signifiers of intelligence and life; no matter how alien they may seem to us.
He begins at home, with the concept of a `shadow biosphere'. Put simply, this is the theory that instead of spawning just once on Earth, life may have begun twice, or three times etc... If provable evidence of a `second genesis' could be found (for example, microbes with left-bonding amino acid systems, as opposed to the right-hand amino bonding of all known life) then the probability that life exists elsewhere in the universe would be elevated to a near factor of 1 (100%). If life spawned twice on one planet, then the chances of it happening anywhere else would be much, much higher. Serious experiments to find terrestrial life from a `second genesis' are currently in the planning stages in America. Aliens among us indeed.
Next Davies examines the theory of panspermia, which puts forward the mind-boggling notion that life on Earth was `seeded' from elsewhere in the universe, such as by hyperextremophile microbes hitching a ride in meteorites. Maybe life was bio-engineered by intelligent, unknowable aliens. Self-replicating probes that plant life on habitable `target' planets are also considered by Davies.
His discussion of the potential types of alien life gets more and more interesting as the book progresses. The size and sheer weirdness of Davies' ideas increases exponentially chapter by chapter. By the end of The Eerie Silence, the book is carrying with it all the usual mind-boggle sentiments of high-concept science fiction writing. People who know me also know that I have an irritating tendency to geek-out about this kind of stuff, but I defy you to read The Eerie Silence and say it isn't interesting. I devoured it - the writer has a gift for imbuing his ideas with a sense of wonder and scale. Some of the thoughts presented within filled me with a sense of, well... a kind of readerly vertigo, as if I were standing on the precipice of something vast and unknowable and ancient. Davies clearly revels in immense ideas such as post-biological intelligence, stellar engineering and terraforming:
"I think it very likely that biological intelligence is only a transitory phenomenon. If we ever encounter extraterrestrial intelligence, I believe it is overwhelmingly likely to be post-biological in nature."
Davies even suggests that the best way to find E.T might be to look for evidence of galactic mega-structures, such as Dyson spheres (massive grids of satellites constructed around entire stars to absorb energy) and Matrioshka brains (super-computers so big that they are built as shells around back-holes, and harness energy from within). These super-structures would emit unmistakable infra-red signatures, and so would be easy to detect.
Stylistically, Davies is a man after my own heart; he employs frequent parenthetic digressions (that is, stuff in brackets) to express several ideas at once, as well as to make sometimes pithy and wry comments on whatever topic is at hand. Structurally, however, the book has some problems. Barely a page goes by without Davies using the phrase "more about this later". While sometimes tantalising, more-often-than-not I found this sort of referential aside to be irritating, drawing attention to the fact that the book's chapter-structure probably isn't optimal.
'The Eerie Silence' isn't unadulterated popular science either. For the polymaths among you, it's also possible to read it as a strikingly philosophical work. Davies takes time to explore such frighteningly eschatological theories as the so-called `heat death' of the universe; an end-game scenario in which all entropy reactions have expired, leaving no thermodynamic energy to sustain life, matter, motion, anything. The concept that the universe is on a slow, unstoppable march towards nothingness reads like an astrophysics expression of Nietzschean nihilism.
But while I can't fault his science, Paul Davies' understanding of history leaves something to be desired. Davies argues that modern science only came around because Judeo-Christian society has a kind of oneness about it which is perfect for spawning scientific method. I respectfully disagree. Correct me if I'm wrong, but my impression was that the rise of mass-organised religion in Europe culminated in the so-called medieval `dark ages' - a period of retarded scientific progression that was finally transcended by the Renaissance, when radical thinkers began to rediscover pre-Christian modes of enquiry (hence `neo-classicism'). It wasn't Judeo-Christian ideologies that lead to the development of modern science, but ancient Greek philosophy, which insisted that the universe isn't random and absurd, but logical, knowable and ordered. That's my two cents anyway; but what do I know?
This is a minor niggle, however; on the whole The 'Eerie Silence' is complexly wonderful, eminently readable and very accessible (hell, if a certified science reprobate like me can understand it, anyone can). There're a few frivolous passages that engage with aliens in pop-culture (such as basic (though admittedly comic) reviews of Contact and Independence Day), which do nothing to squash SETI's image as an organisation populated by sci-fi loving geeks (the dust jacket's author photograph also doesn't help matters - a black and white snap of Davies in all his bi-focal, thick-rimmed, bowler haircut glory). But the best way I can describe The Eerie Silence is to tell you that it's relentlessly, unremittingly interesting.
And unlike most popular science, this is a humanising and encouraging work. A more cynical reading than mine might label 'The Eerie Silence' as a book that romanticises science. But SETI is an on-going endeavour, and it's admirable (and refreshing) that Davies stresses the value of exploration, curiosity and human progress outside of any financial context. There is science here, there is maths here; but it's also a book with an identifiable, emotional heart. Finally, Davies takes great pains to stress that SETI may never succeed; there are so many variables and so much is unknown that some critics don't even think of it as true science. But Davies insists that SETI press on - "The probability of success is difficult to estimate; but if we never search, the probability of success is zero". It turns out that the real sine qua non of SETI isn't money, but hope.