Spacetime metric

In special relativity, the spacetime metric, also called the Minkowski metric', is the metric tensor that describes the line element in Minkowski spacetime.

The metric

The metric can be described by the following line element:

$ds^{2}=c^{2}dt^{2}-(dx^{1})^{2}-(dx^{2})^{2}-(dx^{3})^{2}$

In units where the speed of light, $c$, is one, then the metric in matrix form is

$diag(1,-1,-1,-1)$