Physicist and mathematician — Christian Doppler (Salzburg, 1803 – Venice, 1853) was an Austrian physicist and mathematician. He studied in Vienna and taught in Prague and later in Vienna, where he became director of the first Institute of Physics of the Austrian Empire. In 1842 he published the work in which he described what we today call the Doppler effect: the change in observed frequency of a wave when the source and the observer are in relative motion. Doppler surmised that the phenomenon also explained the apparent colour of double stars, an application later corrected but nonetheless pioneering. His principle is today fundamental in astronomy (redshift), medicine (Doppler ultrasound), meteorology (radar) and in velocity measurement.
Fun fact
In 1845 the meteorologist Buys Ballot verified the effect using a locomotive pulling an open carriage of trumpeters: musicians on the ground with perfect pitch noted the change in tone as the train passed.
Theories and contributions
- Doppler effect — Change in perceived frequency due to relative motion between source and observer: .
- Redshift/blueshift — Optical application: light from a receding source shifts towards the red, the basis for measuring the velocities of galaxies.
Featured in chapters
Linked atoms
8 linked atoms.
16 Onde
20 Relatività ristretta
- The relativistic Doppler effect
- Relativistic velocity composition
- The triangle trick
- Gravitational time dilation
- Hubble’s law
- The expansion of the universe