Christian Doppler

Christian Andreas Doppler was born in Salzburg in 1803, the son of a stonemason. Too frail for the family trade, he was steered into mathematics by a shrewd teacher and worked his way through the Polytechnic in Vienna to professorships in Prague and, eventually, Vienna.

In 1842, while lecturing at the Estates Institute in Prague, he delivered the paper that would carry his name: Über das farbige Licht der Doppelsterne. In it, he argued in little more than a page that the observed frequency of a wave — sound, light, water — depends on the motion of its source. He applied the idea (incorrectly, as it turned out) to the apparent colour of binary stars, which served as the opening chapter of astrophysics.

He was right about the mechanism and wrong about the stellar colours. Experimental confirmation came from Buys Ballot in 1845. Doppler died of tuberculosis in Venice in 1853, before living to see his effect become the measurement tool of an entire century.