Theory of relativity

The theory of relativity, or simply relativity, refers specifically to two theories: Albert Einstein's special relativity and general relativity.

The term "relativity" was coined by Max Planck in 1908 to emphasize how special relativity (and later, general relativity) uses the principle of relativity.

Special relativity

Albert Einstein's 1905 paper "On the Electrodynamics of Moving Bodies" introduced the special theory of relativity. Special relativity considers that observers in inertial reference frames, which are in uniform motion relative to one another, cannot perform any experiment to determine which one of them is "stationary". This is actually Galileo's principle of relativity; Einstein's contribution was to explicitly include electromagnetism within this principle, which required that the Galilean transformations be replaced by the Lorentz transformations. The resultant theory has many surprising consequences. In particular, it requires that the speed of light in a vacuum be the same for all these observers, regardless of their motion, or the motion of the source of the light, since the invariance of the speed of light is a consequence of Maxwell's equations of electromagnetism.

General relativity

General relativity was developed by Einstein in the years 1907 - 1915. General relativity replaces the global Lorentz symmetry of special relativity with a local Lorentz symmetry in the presence of matter. The presence of matter "curves" spacetime, and this curvature affects the path of free particles (and even the path of light). General relativity uses the mathematics of differential geometry and tensors in order to describe gravitation as an effect of the geometry of spacetime. This theory is based on the general principle of relativity, which requires all observers to experience the same laws of physics, not just those moving with uniform speed, hence its name.

References and links

See the special relativity references and the general relativity references.

External links

Living Reviews in Relativity — An open access, peer-referred, solely online physics journal publishing invited reviews covering all areas of relativity research.
Reflections on Relativity — A complete online course on Relativity.
Relativity explained in words of four letters or less
Briefing on Einstein's Theory of Relativity — A terse dose of insight on the subject.
On the Electrodynamics of Moving Bodies
Special Relativity Simulator
A Relativity Tutorial at Caltech — A basic introduction to concepts of Special and General Relativity, as well as astrophysics.
Relativity Gravity and Cosmology — A short course offered at MIT.
Relativity in film clips and animations from the University of New South Wales.

Relativity | Theories

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Special relativity

General relativity

See also

References and links

External links