Langevin was the first to approach the problem dialectically, though as far as he was not then a Marxist. He found the antagonist in heat. The hotter the iron bar the more the atoms will be jostled out of their agreement in direction, and the less will be the amount of magnetism produced by a given current. This, and a number of other similar facts, was known before Langevin was able to calculate what happened in a number of special cases, and a large amount of experimental work by others verified his calculations. The theoretical work on relativity was the first of a series which not merely confirmed Einstein's work but extended it considerably. Langevin was imprisoned in 1940, but later released, after which he escaped to Switzerland when again threatened with arrest. Quartz disc in an alternating electric field contracts and expands as the field changes, and will similarly translate changes of pressure into electric surges.