Under The Microscope

WRINKLES IN TIME by George Smoot and Kay Davidson; Little, Brown & Co; 1993; 321pp; $39.95

We live in an evolving universe that began with a big bang about 15 billion years ago. How do we know this? Before April 1992 there were four principal lines of observational evidence. Firstly, the sky is dark at night, in spite of the many billions of luminous galaxies in the universe. The darkness is largely a consequence of cosmic evolution, or the fact that the universe in the distant past was not filled with the bright galaxies that exist today. Secondly, the universe is expanding, as was first shown by Edwin Hubble some 65 years ago. Thirdly, the stars and interstellar material in the universe are composed almost entirely of hydrogen and helium, and in just the proportions predicted by the cosmological theory of the big bang. And fourthly, the universe is filled with the so-called cosmic microwave background radiation, discovered by Arno Penzias and Robert Wilson in 1964, and which was at once recognized as the radiation left behind from the big bang itself, the relic of the primeval fireball. This radiation was found to have very nearly the same intensity no matter in which direction our microwave receivers are pointed.

Now there is a fifth major piece of observational evidence, and the story of how it was obtained is told in this new book by cosmologist George Smoot and Keay Davidson, a journalist. Wrinkles in Time is the story of the COBE satellite, an acronym for COsmic Background Explorer. This satellite was launched in 1989 on a Delta rocket, and one of the experiments was designed to detect small variations in the brightness of the microwaves in different directions. Such "wrinkles" were predicted to be present and considered to be the seeds from which galaxies, including our own Milky Way, were born. Without these tiny variations in the microwave background, the whole big bang theory would have been in major theoretical difficulty, with no known mechanism for galaxy formation. On the other hand, if they could be found, then a variation of big bang cosmology known as inflation theory, in which the wrinkles originate as quantum fluctuations in the first tiny fraction of a second following the big bang event itself, would be strongly supported.

George Smoot was the principal investigator for the COBE team in charge of the microwave radiometers on the satellite. This was one of three experiments carried, and its aim was explicitly to search for the wrinkles in the microwave background. It was eighteen years of effort from the time the satellite was first planned to the discovery of the wrinkles, and over 1500 scientists and engineers were involved (all their names are listed in an appendix). The result was widely acclaimed when it was announced in April 1992 as one of the most significant astronomical discoveries of the century.

Wrinkles in Time is a lively, well-written and non-technical account of how this epoch-making discovery was made. The book is written in the first person and traces Smoot's scientific career from his graduate work at MIT to his time at the Lawrence Berkeley Laboratory in California, where his interest in the microwave background first germinated in the mid-1970s. After flying microwave receivers in high-flying aircraft, it was clear that to have enough sensitivity to detect the putative wrinkles, a space microwave observatory would be needed. Fifteen years later the COBE program came to fruition.

The book is exciting to read and no prior astronomical knowledge is assumed. My only criticism is that at times the text is too glib and slick, important cosmological details are deliberately glossed over and descriptions of the results of the COBE experiment as "the handwriting of God" and " how God created the world", even though used metaphorically, are somewhat belaboured. Nevertheless I can warmly recommend this very personal account to everyone who is fascinated by the latest developments in cosmology and by the way scientists struggle to collect and analyse data, with many ups and downs on the way to final success.

John Hearnshaw is in the Department of Physics and Astronomy at the University of Canterbury.

John Hearnshaw is Professor of Astronomy at the University of Canterbury and Principal Investigator for the planet search programme of the MOA project.