Homogeneous Spacetimes of Zero Curvature
Homogeneous Spacetimes of Zero Curvature
In the following we show the only possible flat, connected, incomplete homogeneous spacetimes are $H / \Delta$ where $H = \left \{ {\upsilon \in {{\mathbf {R}}^n}\left | {g\left ( {\upsilon ,N} \right ) > 0} \right .} \right \},N$ is a null vector, and $\Delta$ is a discrete subgroup of …