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