Fermat's principle (principle of least time)
Principio de Fermat (del tiempo mínimo)
- Date
- 1662 · confidence high
- Place
- Toulouse, Occitanie, France
- Credited to
- Pierre de Fermat
- Field
- Communication
What was discovered
In January 1662 correspondence with Cureau de la Chambre, Fermat proposed that light travels between two points along the path that minimizes time, not distance, and showed that this principle reproduced the ordinary law of refraction. It became the first great variational principle in physics, a direct precedent to the principle of least action.
The principle remained controversial until the 19th century, when the wave theory of light gave it a physical justification.
What it led to
- Principle of least action in classical mechanics
- Modern variational foundation of geometrical optics
Built on
- Hero of Alexandria's principle of minimum-length reflection
- Ibn al-Haytham's extension to refraction