Meaning of Fermat's principle | Babel Free

Definitions

The principle, which links geometrical optics (or "ray optics") with wave optics, that the path traversed by a ray between two given points is: (in the original "strong" formulation) the one that takes the least time, or (in a weaker but more general formulation) one that takes a time that is "stationary" with respect to variations of the path (so that, loosely speaking, a small change in the ray path entails a very small change in the traversal time).

Equivalents

Examples

“But we now see that, if we use Fermat's principle, a fundamental result of any wave theory, and combine it with de Broglie's assumption about the relation between momentum and wavelength, we are led at once to the principle of least action.”

“[…], Keller simply postulates these rays and finds their direction from Fermat's principle adapted to the hypothesis that these rays exist.”

“1976, Donald E. Tilley, Walter Thumm, Physics for College Students, Cummings Publishing Company, page 558, […] students wishing to pursue this branch of physics further will find that refraction too can be explained in terms of Fermat's principle.”

CEFR level