extraterrestrial: The First Sign of Intelligent Life Beyond Earth, by Avi Loeb. (John Murray), 2022. Pp. 239, 20 × 13 cm. Price £9.99 (paperback, ISBN 978 1 529 30484 8).
Carl Sagan once said that extraordinary claims demand extraordinary evidence. As such, some might doubt Avi Loeb's non-mainstream claim that `Oumuamua (a Hawaiian word for `scout'), which everyone agrees is a body which passed through our Solar System in October 2017 but originated outside of it, is an artefact of an extraterrestrial civilization. However, Loeb makes the point that while there is not that much evidence, the extraterrestrial-artefact hypothesis is orders of magnitude more likely than competing ones. Loeb details several arguments to support his hypothesis. Copious references are provided to his and others' technical papers (both those supporting his hypothesis and those supporting more conventional explanations). All in all, a convincing argument. But the book is about not just `Oumuamua, but also the fact that his hypothesis is perceived to be unlikely not because of the evidence, but because of a refusal to think outside of the box. The book is also a memoir in that Loeb recounts various episodes from his life which, apart from being interesting in themselves, have influenced his thinking. While the idea that `Oumuamua is an artefact of an extraterrestrial civilization is perhaps a bit `wild', Loeb's analysis is very down-to-Earth (so to speak) and evidence-based. Even if you don't agree with everything, indeed, even if you don't even agree with his main thesis, the book is still worth reading.