Example image of eyePlorer eyePlorer map for 'Fermat's principle': Optics Ray (optics) Reflection (physics) Refraction Total internal reflection Huygens–Fresnel principle Snell's law Specular reflection Pierre de Fermat Inflection point Optical path length Saddle point Gravitational lens Ellipse Hero of Alexandria Alhazen Book of Optics Quantum electrodynamics Classical mechanics Variational principle Wave Timeline of electromagnetism and classical optics History of variational principles in physics Scientific phenomena named after people Brachistochrone curve Calculus of variations Analytical mechanics Geometrical optics Story of Your Life Principle of least action Schrödinger equation Maupertuis' principle Fermat's theorem Principle of least effort The Feynman Lectures on Physics Envelope (mathematics) Lagrangian mechanics Kepler problem in general relativity 11th century