An Etymological Dictionary of Astronomy and Astrophysics

A → thought experiment conceived by Einstein (1879-1955) at the age of sixteen in the Swiss town of Aarau where he attended the Argovian cantonal school. If an → observer moved at the → speed of light, pursuing a → beam of light, would he → observe such a beam of light as a spatially oscillatory → electromagnetic field at rest? The answer came some ten years later from Einstein himself by his theory of → special relativity. Accordingly, the speed of light is constant for all observers and no observer can move at the light velocity.

See also: Aarau, the Swiss town, the capital of the northern Swiss canton of Aargau; → paradox.