Geoscience Reference
In-Depth Information
a major industrial centre. He then embarked on research on heat,
being interested in the Second Law of Thermodynamics which had
been formulated in 1850 by Rudolph Julius Emanuel Clausius
(1822-1888). Thermodynamics is defined in some dictionaries as 'the
science of heat as a mechanical agent', and the second law is con-
cerned with the directional flow of heat. Thomson's ideas on heat and
its ability to be transformed into directional force were to have an
important bearing on his geological and geochronological ideas with
the passage of time.
THOMSONON THE AGE OF THE EARTH: A THREE-PRONGED
ATTACK
Infuriated by Charles Darwin's dabbling in geochronology, Thomson
set out to prove through the application of the laws of physics the
actual age of the Earth, and even sought the views of John Phillips as to
the validity of Darwin's geological conjectures. We have a good idea as
to what Phillips's reaction would have been. The chronological issue
of the Earth was tackled by Thomson in three research strands: the
first was in relation to the Sun - he attempted to estimate how long it
had been shining and used this as a corollary for the age of the Earth;
the second took the secular cooling rate of the Earth, thus revisiting
Comte de Buffon's work nearly a century earlier; the third involved an
investigation into the effect that friction caused by tides might have
had on the shape of the Earth. Three very different schemes, but
they ultimately led to much the same conclusion in terms of age
determination.
The age of the Sun
Thomson produced a large volume of work on the Sun and its heat, and
first published on the subject in 1854. He suggested that as the Sun
formed thanks to the collision of meteorites which built up its mass,
the gravitational energy that pulled them towards the Sun was
released as heat. The output of heat, he argued, was far greater during
the early life of the Sun than it was at present, and in an aside pointed
