Hertz, Heinrich Rudolf (1857–1894)

German physicist who studied electromagnetic waves, showing that their behaviour resembles that of light and heat waves.

Hertz confirmed James Clerk Maxwell's theory of electromagnetic waves. In 1888, he realized that electric waves could be produced and would travel through air, and he confirmed this experimentally. He went on to determine the velocity of these waves (which were later called radio waves) and, on showing that it was the same as that of light, devised experiments to show that the waves could be reflected, refracted, and diffracted.

Hertz was born in Hamburg and studied at Munich and Berlin. He was professor at Karlsruhe 1885–89 and at Bonn from 1889.

From about 1890, Hertz gained an interest in mechanics. He developed a system with only one law of motion: that the path of a mechanical system through space is as straight as possible and is travelled with uniform motion.

The unit of frequency, the hertz, is named after him.