Fortean Times, February 2003

XTL: Extraterrestrial life and how to find it
Simon Goodwin with John Gribbin
Weidenfeld & Nicholson 2002
PB, £12.00, pp192,illus, index ISBN: 1 84188 193 7

Over the past couple of years, there's been a glut of books arguing the scientific case for (or against) the likelihood of life on other planets. This latest, a slim but beautifully illustrated volume by stellar astronomer Simon Goodwin and veteran science writer John Gribbin, aims to provide an easy introduction to the subject, but disappointingly tells only half the story.

Despite its marketing-friendly title, 'XTL' concentrates almost wholly on the search for planets that could potentially harbour life, and not the consideration of extraterrestrial life itself. It may be a subtle distinction, but it's the intermingling of biology and geology with astronomy that makes the scientific search for extraterrestrial life such an exciting field. The best books on the subject, such as 'Here be Dragons' (OUP 2000, reviewed FT137) by astronomer David Koerner and biologist Simon LeVay, emphasise such a multidisciplinary approach.

Goodwin and Gribbins however confine themselves for the bulk of the book to the search for planets around other stars, with some consideration of likely signs of life such as oxygen and liquid water. As such it is an excellent introduction to the emerging field of extrasolar planetary astronomy, with a valuable list of the 60-odd planets that had been discovered as the book went to press at the end of 2000 (as of September 2002, Nasa had counted a total of 101, which goes to show the current rate of progress in the field). Goodwin also highlights some interesting anomalies among the planetary systems that have been detected, including one where at least one planet appears to orbit both stars in a binary system, something that runs counter to current models of planetary formation.

But given the book's premise, it is frustrating to have the question of how life began on Earth - vital to our understanding of how life might arise on other planets - written off in a single paragraph. Goodwin also limits his brief speculation on the possibility of alien life to 'life as we know it', which takes half the fun out of it.

There is a good final chapter on recent and upcoming SETI projects, but the excitement is somewhat diluted by Goodwin's invocation of Fermi's Paradox - which basically states that if there was advanced life elsewhere in the galaxy, we'd have seen some sign of it.

Given that Goodwin estimates that at least one in 20 stars in our galaxy have planets, including at least halve of all sun-like stars, the odds on finding signs of some kind of life appear fairly good. But if that life has more in common with pond scum than the wise space brothers of popular myth, it's discovery is hardly going to be 'the most profound discovery in the entire history of human civilisation' that Goodwin claims.

Still, any book that closes with a full page picture of the Metaluna Mutant from 'This Island Earth' has to have something going for it.