Other Worlds: The Search for Life in the Universe

  • Michael D. Lemonick
Simon & Schuster: 1998. Pp.272 $25

Alien Life: The Search for Extraterrestrials and Beyond

  • Barry Parker
Plenum: 1998. Pp. 254. $27.95, £16.94

Astronomical and Biochemical Origins and the Search for Life in the Universe: Proceedings of the 5th International Conference on Bioastronomy (IAU Colloquium 161)

Edited by:
  • C. B. Cosmovici,
  • S. Bowyer &
  • D. Werthimer
Editrice Compositori: 1997. Pp. 814. $100, Lire 160,000 (pbk)

The progress of science depends not only on asking the right question, but also on having the technical ability to make a reasonable attempt at producing an answer. Here the question is: “Are we alone in the Universe?”. There are three possible answers: “Yes”, “No” and “Don't know”. At the end of the twentieth century we are still firmly stuck with the last one. Moving to either of the other possibilities would be one of the most significant steps in the history of scientific endeavour.

The answers “Yes” and “No” would be equally amazing, but the former would never be accepted. The Universe is so vast, and has already existed for so long, that we would never prove to everyone's satisfaction that a scintilla of life does not exist beneath some far-off stone, or on a planet behind one of the billions of distant stars.

But if we are not alone in the Universe, why have our co-inhabitants not been to see us, or at least phoned? Why is the Earth not littered with the remnants of crashed interstellar probes? Why are our skies not alive with the cross-talk of millions of interstellar communications? Our technological sophistication is not a serious problem here; the existence of extraterrestrial life should be obvious just by looking and listening.

If it is assumed that life is ubiquitous, we then have to ask if it is all based around the chemistry of carbon, and whether water is the universal solvent. Is the creation of life inevitable wherever it is warm and wet for aeons? Does all universal life depend on DNA, RNA and protein? And does it always take about 2.5 billion years for blue-green algae to evolve into Nature readers?

Why are there millions of living species on Earth but only one species of high intelligence? Does some extraterrestrial life also become intelligent, inquisitive and technological? Does it also develop the potential for self-destruction? And, assuming that life does exist out there, where does life on Earth rank in the intelligence and development league table of the Universe?

These and other bioastronomical questions have taken on greater urgency with the recent discovery of a host of planets around nearby Sun-like stars, hints that life could have existed on our neighbouring planet Mars, and the realization that conditions on Jupiter's moon Europa might be conducive to microbial life. This urgency is spawning conferences and books.

Astronomical and Biochemical Origins and the Search for Life in the Universe is a collection of 84 papers and reviews that were given in July 1996 at a bioastronomy conference in Capri, Italy. The topics include organic material in interstellar clouds, comets and meteorites; the search for planets around nearby stars and the form and distribution of these planetary systems; the origin and evolution of life and intelligence; and SETI, the search for extraterrestrial intelligence in the radio, infrared and optical wavebands. The author list is replete with the names of the famous, and to have three Nobel laureates at the same small meeting is most unusual. The papers are erudite but remarkably easy to understand: the interdisciplinary nature of this field forces researchers to keep jargon and obscuration to a minimum.

Other Worlds by Michael D. Lemonick and Alien Life by Barry Parker are both first-class, entertaining and authoritative examples of the art of scientific popularization; it is very difficult to choose between them. Both distil the contents of the bioastronomy enterprise and present a highly readable account of present progress and possible future developments.

Lemonick spent a great deal of time travelling to observatories and laboratories and talking to the astronomers and other scientists who are working at the frontiers of this fascinating subject. His account is full of anecdotal insights.

Parker, on the other hand, concentrates on the science and ideology. He contrasts panspermia with spontaneous generation, reviews the various forms of the anthropic principle, considers the influence of the discovery of extremophiles on the extent of stellar habitable zones, re-examines the Drake equation, and balances the expected waves of galactic colonization against the perceived absence of the ‘calling cards’ of extraterrestrial visitors. His speculation is firmly based on sound, well explained scientific principles, and he encourages us to prepare for the inevitable — and not too distant — conversation with an alien.