Linked from

The 17 pages that link to Fermat's principle, each with the reason it gives.

• RefractionRelated: Its least-time formulation yields the law governing refraction at an interface.

• Gravitational lensingRelated: Lensed images correspond to stationary travel-time paths through the gravitational field.

• Snell's lawRelated: Applying it to travel across an interface yields the sine relation in Snell's law.

• Atmospheric refractionRelated: It explains curved atmospheric ray paths through variation in light’s speed.

• Optical path lengthRelated: Stationary travel time is equivalent to stationary optical path length in a given medium.

• Geometrical opticsRelated: It provides a variational rule from which reflection and refraction laws can be derived.

• Principle of least actionRelated: It is an optical stationary-time principle analogous to stationary action.

• WavefrontRelated: Its stationary paths determine how optical wavefronts advance.

• Hamilton's principleRelated: It is a related variational principle, with travel time replacing mechanical action.

• Law of reflectionRelated: Its least-time construction derives equal incidence and reflection angles.

• Brachistochrone curveRelated: The analogy with light refraction offers a route to the brachistochrone solution.

• Ibn SahlRelated: It offers a later variational account of refraction that can be compared with Ibn Sahl's construction.

• Fagnano's problemRelated: The equal-angle reflection rule mirrors the path condition used in optical ray tracing.