Geology Reference
In-Depth Information
remoteness and, like Hutton a century and a half ago, we still
see 'no vestige of a beginning'
.
The audience, many of whom were lay people with no geo-
logical experience, was captivated and enthralled. Most had
never before stopped to think how old the Earth might be, they
had di~culty in imagining time that was so vast, events that
were so remote, a world without Man, without beginning or end.
Questions were asked and much banter exchanged. Finally, the
Professor of Botany stood up to say that at least to him 'it was
highly satisfactory that the Earth was older than the Universe!'.
Everyone laughed and the proceedings broke up on a note of
jollity.
The Earth was older than the Universe?
Astronomers had often been asked to assist in estimating the
age of the Earth, and had frequently contributed to the debate,
while at the same time trying to calculate for themselves the age
of the Universe and various other cosmic bodies such as the sun.
During these deliberations, one of the long-standing questions
had become: why does the sun shine? What kept it going, giving
o¬ so much heat? At the end of the previous century Kelvin had
estimated that contraction of the sun due to gravity would keep
it radiating (shining) for only twenty million years, and of course
he had used this calculation as strong support for his arguments
regarding a 20-million-year-old Earth. However, once radio-
activity had been discovered and the Earth was shown to be
much older than Kelvin had predicted, then the question as to
what kept the sun shining became even more critical, for either
the Earth must have existed for longer than other bodies in the
solar system, or the sun also had to be much older than 20 mil-
lion years. It therefore seemed logical to conclude that if
radioactive elements were responsible for keeping the Earth hot
then this was also what kept the sun hot. But in the 1920s when
