October 30: From Nazi Germany to the USSR

Nobel Prize-winning experimental physicist Gustav Hertz died in Berlin at 88 on this date in 1975. Hertz, who lived most of his life as a Lutheran in Germany, probed the energy levels of atoms, which helped to confirm Niels Bohr’s model of the atom and to prove that atoms can absorb internal energy only in definite quanta. His work, with research partner James Franck, earned the Nobel Prize in 1925. But with the Nazi move to power in 1933, Hertz refused to sign a loyalty oath, then resigned his positions and moved to the USSR. There he headed a research laboratory from 1945 to 1954 and conducted work that helped the Soviet Union become a nuclear power and brought him a Stalin Prize. Hertz returned to East Germany in 1954 as director of the Physics Institute at Karl Marx University in Leipzig. Hertz was the nephew of Heinrich Hertz, who discovered radio waves. “Following Niels Bohr’s theory for the structure of the atom, an experiment to verify it was made by James Franck and Gustav Hertz in 1913. A potential difference was applied to a tube containing a low-pressure gas. When the current through the tube was increased, the potential difference increased until it reached a certain voltage, then it was suddenly reduced. The result gave support for Bohr’s theory in which the electrons have only specific discrete energies. The freely moving electrons could, at a certain energy, make the electrons of the gas atom move to a new orbit.” —Nobelprize.org