Life Beyond Earth - Luigi Vacca ****

Astrobiology is an unusual science in that there’s no clear, undisputed evidence that its subject of study – extraterrestrial life – even exists. It’s still an active field of research, though, with observational astronomers scouring the skies for telltale signs of life, and theoreticians tying themselves in knots trying to explain why we haven’t seen any of those signs yet. This book deals almost exclusively with the second of those topics.

Before going any further, it’s worth defining exactly what we mean by ‘life’ in this context. If you’d asked Aristotle or Shakespeare or Charles Darwin to define life, they’d give pretty much the same answer, relating to biological processes. If we can’t detect such processes at a distance of many light years, that’s not really a great surprise: the latest generation of telescopes has only just got to the point where it might be possible even in principle. But many popular discussions of extraterrestrial life, this book included, aren’t talking about life in the biological sense at all. They mean technology, in the form of space vehicles, radio communication and such like. These are things we might actually be expected to detect, so the question posed in the book’s subtitle – ‘Why Are We Still Waiting to Meet Aliens?’ – is a sensible one to ask.

This is referred to as the Fermi Paradox – a name that’s strikingly memorable but not particularly accurate, because it’s not really a paradox at all. That would only be the case if we were absolutely certain the galaxy is filled with lifeforms that we ought to be able to detect easily. This may have been the view of Enrico Fermi, the Italian physicist who gave his name to the paradox after famously asking the question ‘Where are they?’ in 1950, but with our current understanding of the relevant areas –  astronomy, biology, technology and so on – it seems far less clear cut. That’s the point that Vacca makes in the first half of this book.

The second half then summarises some of the many solutions to the Fermi Paradox that have been put forward. Perhaps the most obvious of these is the idea that technological civilisations are virtually non-existent, or at least extremely short-lived before they destroy themselves (or ‘regress’ to the arguably more stable and civilised level of Aristotle, Shakespeare et al). Another possibility is that, for one reason or another, technologically advanced civilisations deliberately hide their presence, or (and this is my personal favourite) prefer an introverted virtual reality existence because it’s cheaper, safer and more interesting than living in the the real world.

When it comes to science books, there’s often a choice between serious and authoritative on the one hand, or thought-provoking and entertaining on the other. If you’re looking for the first kind, the best you could do is probably The Great Silence by Milan Cirkovic, a professional philosopher who specialises in this field. Luigi Vacca’s book, on the other hand, is definitely in the second category. He’s a computer scientist by profession, writing here about a subject that fascinates him – which helps bring it to life for a general audience without going into too much technical detail (although there are fifteen pages of bibliographical notes at the end, for anyone who’s interested in delving deeper). His English is also wonderfully clear and easy to read, which isn’t always the case with non-native speakers. So if you’re new to the whole subject of the Fermi Paradox, this is a great introduction.

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Review by Andrew May - See all Brian's online articles or subscribe to a weekly email free here