# Contents

## Idea

In physics the theory of special relativity describes dynamics in physical spacetime in absence of a field of gravity.

Specifically, it models

If instead of restricting to Minkowski space, spacetime is allowed to be an arbitrary pseudo-Riemannian manifold one speaks of the resulting framework as the theory of general relativity.

Mathematically, special relativity is essentially the theory of Minkowski space as a pseudo-Riemannian manifold, hence equipped with the constant metric tensor which at each point is the bilinear form with signature $(-,+, \cdots, +)$ or else $(+,-,\cdots, -)$ (depending on convention). The null-vectors in this metric characterize the speed of light. The linear isometries of this metric are the Lorentz transformations and the fact that with the Minkowski metric these also preserve, hence, null rays is the mathematical model for the famous phenomenological observation that “the speed of light is the same in all reference systems”.

## References

Revised on September 8, 2013 15:32:31 by Urs Schreiber (89.204.135.167)