| Description | Correspondence re Sullivan's projected book on plate tectonics.
Includes photocopies of correspondence, December 1930-January 1931, exchanged between Einstein and William Barrett who had postulated a relation between the magnetic and rotational fields of the earth.
Blackett's letter of Septemer 1973 gives an account of his own involvement in a similar hypothesis:
'Several years ago I thought that this was a plausible theory and I did a lot of experimental work to find out whether there was such a relationship. In fact all my work in this field proved wrong.
If you want to recover what many of us thought in the early 1930s then you might read my article in Nature ("The Magentic Field of Massive Rotating Bodies", Nature Vol. 159, May 17, 1947) about the hypothetical relationship between the magnetic and rotational fields. Further when it was shown that the earth's magnetic field reverses several times in a million years at the same time at all places on the earth's surface it was clear that the earth's field must be originating from the dipole of an atom.
What a lot has happened since we met. I was very sad when all my thoughts and work on the rotation body proved false. However there were several very important conclusions: firstly, the proof of the reversal of the magnetic field sets enormous problems on the motion of the earth's core. Then the view was that there exists in the core some very complicated phenomena of reversal of the fields so frequently in geological time. The failure of the experiment on rotational bodies led me to design a magnenometer of great sensitivity and this proved very valuable for the study of the magnetic fields on the earth's mantle. These magnetic studies over several years have played a major part in the development of continental drift and, to use the present jargon, to create a system of geological plates floating near the surface of the earth'. |