Types of quantum field thories
This is naturally a spacetime.
The isometry group of Minkowski space is the Poincaré group. The study of Minkowski spacetime with its isometries is also called Lorentzian geometry. This is the context of the theory of special relativity.
This is due to (ChristodoulouKlainerman 1993).
Gravitational stability of Minkowski space is proven in