1918 - Science

Science

Frankfurt-am-Main-born Berlin chemist Otto Hahn, 39, and his Viennese-born physicist colleague Lise Meitner, 39, isolate the most stable isotope of the element protactinium, the long-lived mother substance of the actinium series. They have used the radioactive recoil discovered by Hahn before he entered the German military; he will go on to discover uranium Z (the first case of a nuclear isomerism of radioactive kinds of atoms), and she will investigate the behavior of beta rays and the disintegration products of radium, thorium, and actinium (see 1938).

The mass spectrometer invented by Toronto-born University of Chicago physicist Arthur (Jeffrey) Dempster, 32, revolutionizes chemical analysis by making it possible to measure the weight of isotopes and detect chemicals in minute quantities (see uranium 235, 1935).

Space, Time, Matter (Raum, Zeit, Materie) by mathematician Hermann Weyl at Zürich incorporates Weyl's findings on relativity while revealing a strong interest in philosophy.

Mathematician Georg Cantor dies in a psychiatriac hospital at Halle January 6 at age 72, having founded set theory and introduced the concept of transfinite numbers, which are indefinitely large but distinct from each other. Afflicted with mental illness beginning in about 1884, he remained active until at least 1897.