MadSci Network: General Biology

Re: Is looking for life on other worlds unscientific?

Date: Thu May 15 02:16:28 2008
Posted By: Will Higgs, Consultant
Area of science: General Biology
ID: 1206930885.Gb

Science is a way of thinking. Things, including things that may not exist, are neither scientific nor unscientific. New discoveries and theories such as quantum physics were unknown once, but scientific theorising and experiment accumulated evidence that persuaded people of their usefulness. Note that I say "usefulness", not "proof". Scientific theories, and even definitions are only used until something better comes along. Newton's physics was perfectly adequate for most applications, including sending men to the moon, but most scientists now accept that Einstein and quantum physicists have added new and valuable aspects to our understanding of matter. Designers of new computer processors and data storage find quantum concepts increasingly essential.

I agree that so far we have no evidence of life elsewhere. There are, however, several ways in which we can accumulate evidence about its probability, including analysis of the chemistry of other parts of the universe. It appears that wherever we look, the stars and interstellar gas are made of the same stuff that we are, so that if life did arise easily and quickly on Earth, there seems no reason why it shouldn't elsewhere. New equipment is allowing astronomers to detect planets orbiting nearby stars, and a large proportion of stars seem to have them. If we are able to analyse the atmospheres of distant planets in the future, an atmosphere rich in oxygen like our own would be difficult to explain except as a product of life.

I also agree that direct evidence of extraterrestrial life seems a remote possibility at present, unless it is found within our own solar system. Radio signals or visits from technological beings are ruled out (as far as we know) by the distances involved. I think it is much more likely that the commonest forms of life on other planets will be similar to bacteria, possibly living underground where there is liquid water and protection from radiation and the effects of meteorite impacts, as they may be on Mars or Titan. Such organisms are known on Earth, some bacteria can live in boiling water, or deep underground, feeding on simple chemicals in the rocks.

Who says life has not evolved many times on the Earth ? How would we know ? Paul Davies, on his recent lecture tour and in his book "The Goldilocks Enigma" suggests that there could be micro-organisms living in extreme environments on Earth that are unlike typical life-forms, having evolved separately or arrived from space. Microbiologists have hardly begun to classify bacteria, there are thousands, probably millions of different kinds in a handful of rich garden soil.

I don't think any well-conducted scientific research is a waste of money. Indeed, one of the most positive things the US is doing at present is its continuing enormous contribution to pure research and investment in space exploration. Unfortunately, the mass media is not an appropriate place to publicise scientific discovery and most people receive a garbled version based upon spectacular and therefore newsworthy events or disasters. Their appreciation of questions such as extraterrestrial life is indeed an act of faith, but a retrospective one, based upon ignorance. There are other kinds of faith, forward-looking ones such as religion and the desire to know more and more about the universe. It is these that make us human, many people have sacrificed much to make them possible today and they should not be cynically abandoned.


Davies, P. 2007. The Goldilocks Enigma; Penguin, London.
Why does the Universe seem to be "just right" for life ? Thought-provoking and clearly explained.

Gold, T. 1998. The Deep Hot Biosphere; Springer, New York.
Although many of Gold's wilder claims have been disputed, his core thesis that large quantities of organisms are living deep underground just won't go away.

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