Abstract

To explain the origin of thorium, the Austrian geophysicist Kirsch in 1922 postulated a hypothetical isotope, thoruranium , by analogy with actinouranium. The theoretical life-time of thoruranium was predicted as being too short for it to have survived in the recent geological past. Available geological data was not inconsistent with this hypothesis, but neither did it confirm it. Within five years one new piece of geological evidence, which appeared not to conform with predictions based upon this alleged U-236, was accepted even by Kirsch as sufficient to falsify his theory. However, during the 1940s, U-236 was produced artificially, and its characteristics were found to conform with those postulated for thoruranium. Subsequent research on the origin of the universe has confirmed that indeed a natural endowment of U-236 did once exist in considerable abundance