Simon Singh

BIG BANG

The most important scientific discovery of all time and why you need to know about it

This is a book about how our scientific understanding of the universe has developed. Most societies have had a mythological account of how the universe came into being, but scientific attempts to investigate the question began with the Greeks.

Eratosthenes, who was born in about 276 BC, produced reasonably accurate estimates of the sizes of the Earth, Moon, and Sun and of their distances from one another. Another Greek, Aristarchus, suggested a Sun-centred solar system, but this was not widely accepted in antiquity. Not until the seventeenth century, in Europe, did the true state of affairs come to be widely recognized, and even as late as 1633 the Church was so hostile to the idea that Galileo was forced to recant.

Gradually, however, a Sun-centred cosmos came to be accepted, even by the Church. By 1900 cosmologists had come to believe that the universe (taken to be coterminous with our own galaxy) was eternal and static, and this was the picture that Einstein assumed when constructing his general theory of relativity.

This picture began to change in the 1920s, thanks to the work of Edwin Hubble, who showed that most nebulae were distant galaxies and that they were receding at speeds that were proportional to their distances. Hence it was realized that the universe was not only vastly bigger than had been believed hitherto, it was also expanding, which to most people implied that it had had a beginning in a much more condensed state and was not eternal.

Some physicists continued to favour a steady-state universe, however. One of these was Fred Hoyle, who first introduced the term "Big Bang" in a radio broadcast as a derisory epithet for the rival theory. The question continued to be debated throughout the 1950s but the discovery of the CMB (cosmic microwave background) radiation by Penzias and Wilson in the 1950s pretty much settled the question in favour of the Big Bang. This was confirmed in 1992 when the COBE satellite detected tiny variations in the CMB radiation that would have seeded the development of galaxies.

Singh is an accomplished writer and he tells the story with an assured touch. At least in outline, the events he narrates will be familiar to readers of books and articles on popular science, but he explains the issues clearly and provides interesting background information about the personalities involved. As an introduction to cosmology for those who know little about it, his book could hardly be bettered.

Big Bang cosmology is now the established orthodoxy and it appears unlikely to be abandoned in the foreseeable future. Many major questions remain, however, and Singh looks briefly at these in his short Epilogue. There are also suggestions for further reading for each of the chapters.

30 September 2006