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Principle of relativity

In physics, the principle of relativity is the requirement that the equations describing the laws of physics have the same form in all admissible frames of reference.

For example, in the framework of special relativity, the Maxwell equations have the same form in all inertial frames of reference. In the framework of general relativity, the Maxwell equations or the Einstein field equations have the same form in arbitrary frames of reference.


Several principles of relativity have been successfully applied throughout science, whether implicitly (as in Newtonian mechanics) or explicitly (as in Albert Einstein's special relativity and general relativity).

Wikibooks: Special Relativity

– An open access, peer-referred, solely online physics journal publishing invited reviews covering all areas of relativity research.

Living Reviews in Relativity

– A complete online course on Relativity.

MathPages – Reflections on Relativity

Special Relativity Simulator

– A basic introduction to concepts of Special and General Relativity, as well as astrophysics.

A Relativity Tutorial at Caltech

– A short course offered at MIT.

Relativity Gravity and Cosmology

from the University of New South Wales.

Relativity in film clips and animations

visualizing the effects of special relativity on fast moving objects.

Animation clip

The mathematics of special relativity presented in as simple and comprehensive manner possible within philosophical and historical contexts.

Relativity Calculator – Learn Special Relativity Mathematics