Geoscience Reference
In-Depth Information
the study of radioactivity in geology. He failed to acknowledge fully
this new science and to see its implications. It is perhaps too easy
to castigate him for this and regard him as a scientific failure, and
at the same time forget the scientific achievements that resulted
from his brilliant intellect. Thomson was without doubt one of the
pre-eminent scientists working in nineteenth-century Britain.
Shortly before Kelvin died, Ernest Rutherford (1871-1937), a
young New Zealander who was Professor of Physics at McGill
University, Montreal, was waiting to give a lecture on his work to an
assembled audience at the Royal Institution in London in 1904.
Looking out from the lectern Rutherford was horrified to see the
79-year-old Kelvin sitting in the front row, and he realised that the
final section of his lecture would discredit a great deal of the older
man's geological research on the age of the Earth. He had no option but
to begin, and was highly relieved shortly afterwards to see Kelvin
begin to slumber. Throughout the lecture Kelvin remained lost to
the world but awoke at the critical point when Rutherford was about
to deal with geochronology. He recalled later: 'I saw the old bird sit up,
open an eye and cock a baleful glance at me! Then a sudden inspiration
came to me, and I said Lord Kelvin had limited the age of the earth,
provided no new source of heat was discovered. That prophetic utter-
ance refers to what we are now considering tonight, Radium! Behold!
the old boy beamed upon me!' Initially while Kelvin recognised that
the radioactive material radium produced heat, he refused to believe
that it produced the heat itself, and rather argued that the radiummust
have gained from an external source the heat that it subsequently
emitted. However, soon afterwards he privately accepted that the
discovery of radium had made some of his conclusions regarding
secular cooling of the Earth difficult, but he never made this view
publicly known. Perhaps it would have been best if he had slept
through all of Rutherford's lecture, but there is little doubt that
he saw the dawn of radioactivity herald the demise of his own
geochronology.
