From Citizendium, the Citizens' Compendium
 String theory: Add brief definition or description
 General relativity: A mathematical theory relating gravity to nonEuclidean distortions in the geometry of space and time introduced by mass and energy, and reducing to the special theory of relativity in localized regions of space and time. ^{[e]}
 Mathematical physics: Add brief definition or description
 Statistical mechanics: Add brief definition or description
 Optics: A field of scientific, technological, and engineering study and application concerned with understanding light, — typically in the visible, ultraviolet, and infrared ranges of the electromagnetic spectrum — and harnessing it for useful tasks. ^{[e]}
 Condensed matter physics: Add brief definition or description
 Atomic, molecular, and optical physics: Add brief definition or description
 Nuclear physics: A branch of the science of physics involving nuclei of atoms, subatomic particles, and any reactions involving them. ^{[e]}
 Materials physics: Add brief definition or description
 Computational physics: Add brief definition or description
 The standard model: Add brief definition or description
 Particle accelerators: Add brief definition or description
 Huygen's principle: Add brief definition or description
 Lagrangian mechanics: Add brief definition or description
 Waves: Add brief definition or description
 Standing waves: Add brief definition or description
 Harmonic oscillator: Add brief definition or description
 Relativistic quantum mechanics: Add brief definition or description
 Fluids: Add brief definition or description
 Perturbation theory: Add brief definition or description
 Strong force: Add brief definition or description
 Fermions: Add brief definition or description
 Leptons: Add brief definition or description
 Hadrons: Add brief definition or description
 Dirac equation: Add brief definition or description
 KleinGordon equation: Add brief definition or description
 Čerenkov radiation: Add brief definition or description
 Refractive index: Add brief definition or description
 Ferromagnetism: Add brief definition or description

