# Gibbons–Hawking effect

For example, Schwarzschild spacetime contains an event horizon and so can be associated a temperature. In the case of Schwarzschild spacetime this is the temperature $T$ of a black hole of mass $M$, satisfying $T \propto M^{-1}$ (see also Hawking radiation).
A second example is de Sitter space which contains a particle horizon. In this case the temperature $T$ is proportional to the Hubble parameter $H$, i.e. $T \propto H$.