Cosmic Dragons: Life and death on our planet by Chandra
Wickramasinghe, Souvenir Press, 拢18.99, ISBN 0285636065
THE case for interstellar panspermia鈥攖he seeding of Earth by
microorganisms from the stars鈥攊s getting stronger. For one thing, the
oldest evidence of life has been pushed back to about 4 billion years ago,
greatly shrinking the time available for life to evolve from non-life. For
another, we now know that bacteria can survive space-like conditions: extreme
heat, desiccation for a quarter of a billion years in a salt crystal, impacts at
10 kilometres per second if embedded in a suitable matrix, and hard radiation
even inside a nuclear reactor. Add to this the general acceptance of planetary
panspermia, the transference of microorganisms between objects in the Solar
System, and it is hard to avoid the conclusion that interstellar panspermia is
an idea whose time has come.
The chief proponent of this controversial idea is astronomer Chandra
Wickramasinghe. In his entertaining and thought-provoking Cosmic Dragons, he
sets out the case in thorough and compelling detail. In case you wondered, the
鈥渄ragons鈥� of his title are comets, the hypothetical means by which biological
material is ferried back and forth between planetary systems and interstellar
space.
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You can鈥檛 help rooting for Wickramasinghe. After all, if life turns out to be
a cosmic rather than a planetary phenomenon, it will undoubtedly be the most
important and mind-blowing discovery in the history of science. Fred Hoyle,
Wickramasinghe鈥檚 long-time friend and collaborator who died recently, believed
that the case would not be proved in his lifetime. One wonders whether, if he
had lived another 10 years, he would have been quite so pessimistic.