Before the advent of modern science, there was a range of beliefs about the age of the Earth, and of the universe. Some Christians believed that God created both a mere 6,000 years ago. Ancient Hindu texts, in contrast, talk of an infinite cycle of creation and destruction.
Towards the end of the 18th century, geologists began to realize that the Earth must be much more ancient than had been thought (at least in Europe) – perhaps millions if not billions of years old. However, into the 20th century the scientific consensus was that the universe itself was eternal, and in a ‘steady state’. Stars might be born and die, but the dimensions of the universe were fixed and unchanging.
A chink in this theory came in the 1920s when the American astronomer Edwin Hubble observed that the further away a galaxy is from us, the faster it is receding. He concluded that the universe is expanding, and that this expansion started in a single great explosion, which became known as ‘the Big Bang’.
Arguments persisted between the proponents of the steady state and those of the Big Bang. Then in 1964 two radio astronomers working in New Jersey, Arno Penzias and Robert Wilson, noticed that their sensitive microwave receiver was suffering from constant interference, the same in all directions, with a wavelength representing a temperature of 2.7 degrees above absolute zero. At first they thought the phenomenon might be caused by the proximity of New York City or by pigeons defecating on their instrument. Eventually they realized that what their receiver was picking up was an echo of the Big Bang. If you retune your radio, part of the ‘white noise’ you hear between stations is this very same echo from the beginning of time.
Cosmologists have now come up with a timetable that positions the Big Bang about 13.8 billion years ago, at a single point, a singularity, whose density and temperature were infinite. Once expansion started, it came at unimaginable speed. Between 10-36 and 10-32 seconds, the volume of the universe expanded by a factor of at least 1078 . 1 At this stage the only matter was elementary particles such as quarks and gluons. At about 10-6 seconds, as expansion slowed down and temperatures fell, quarks and gluons came together to form protons and neutrons. A few minutes later the temperature had cooled further, to about 1 billion degrees, and protons and neutrons combined to form the nuclei of deuterium and helium, though most protons remained unattached as hydrogen nuclei. Eventually, the positively charged nuclei attracted negatively charged electrons to create the first atoms. These simple atoms were to become the building blocks of the stars.
‘Why does the universe go to all the bother of existing?’
Stephen Hawking, A Brief History of Time (1988)
