Foundational Theories


Special Relativity

The speed of light is the speed limit for the universe. Light travels at the same speed regardless of relative position. When applied to Newtonian physics, it provided new relativistic formulas for motion. 4

Quantum Theory

Hot objects emit electromagnetic radiation. If the energy carried off by radiation is added together, the total energy produced is calculated to be infinite. Max Planck deduced that if energy was emitted in discrete packets, quanta, it would be a finite quanity of energy. Radiation of frequency v comes in quanta of energy E = hv where h is Planck's constant . Photons are the quanta of light. This began the idea of wave-particle duality and quantum mechanics. 4



Quantum Mechanics

Explanation of atomic particles including bosons and fermions . Describes the laws of motion for atomic particles and describes the spin of electrons that had previously been predicted. 5

General Relativity

Einstein saw that special relativity was in contradiction with Newtonian gravity because the classical interpretation required the instantaneous transmission of force between two objects. General relativity accounts for a discrepancy in Mercury's orbit, predicted that light would be bent by a gravitational field (proved by Eddington during a solar eclipse), predicted the existence of black holes and gravitational radiation, and describes an expanding universe. "Gravity is a manifestation of the curvature of space-time." The equation for space-time geometry becomes Gµv = 8piGTµv where G is Newton's contant and Tµv is the distribution of energy and momentum. 4



Quantum Field Theory

Quantum Field Theory is the unification of quantum mechanics and special relativity. This union required the creation and annihilation of quanta. QFT expresses elementary particles as mathematical points of zero size (quantum effects give rise to apparent size by "smearing" them). It allows the construction of gauge theories characterized by Lie group symmetry structure. Of these theories, the Standard Model is based on the Lie group SU(3)xSU(2)xU(1) . 4

Kaluza-Klein Theory

A dimension is either large and directly observable or small and practically invisible. Present particle accelerators can only observe to about 10^(-18)m, so any curled-up dimensions smaller than that are currenly unobservable. The properties of these curled-up dimensions determines the properties of the elementary particles. 1