Microbes among the stars: a rather outrageous new theory

Interstellar dust, a widespread constituent of our galaxy, may be the residue of old microbes, according to British cosmologist Sir Fred Hoyle and his colleague N. Chandra Wickramasinghe of University College in Cardiff, Wales. What is more, they say, "The most powerful hypothesis to account for the facts [ about the dust] is that microbiology operates on a cosmic scale."

Once again, the dynamic duo of astrobiology has come up with a thesis that seems certain to outrage many other scientists.

To orthodox thinking, it was impish enough of them to suggest, nearly a decade ago, that interstellar dust contained such biologically interesting material as cellulose. It was even more outrageous -- "flamboyantly irresponsible" one distinguished biologist said -- to go on to propose that simple life forms might arise within the dust or evolve inside comets which have been seeding Earth itself with primitive organisms since the planet's formation. To insist now, as they do, that "interstellar dust grains must all begin life as viable bacterial cells" will strain their critics' capacity for epithets.

However, the "flamboyant" notions of Hoyle and Wickramasinghe have a tough vitality. They are widely discussed even by those scientists who profess to despise them. They have sparked a number of independent investigations -- showing they play a fruitful scientific role even when such investigations may be aimed at refluting them. And at least a few other scientists have come along part way with their thesis.

W. M. Irvine, S. E. Leschine, and F. P. Schloerb of the University of Massachusetts, for example, have looked into the possibility of biological materials in comets and conclude "that comets may have played a role in the origin and conceivably even in the subsequent evolution of terrestrial life."

In an essay recently published in New Scientist, Hoyle and Wickramasinghe explain how they have arrived at their conclusions.

They began more than a decade ago by trying to understand the nature of the interstellar dust. This meant, among other things, coming up with a proposed composition whose electromagnetic reflection and emission characteristics match those astronomers actually measure for the dust.

This quest, they say, has led them to develop and discard a number of theories. Now, after many years of research, they say the best match to the astronomical data they can find is a mix of materials that could well be produced by, and consist of, a population of living microbes and their remains.

While most other scientists are likely to dismiss this out of hand, they will grudgingly pay attention. As Armand Delsemme of the University of Toledo, Ohio, has noted: "We need people like Hoyle and Wickramasinghe to shake up all our preconceived ideas."

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