Gibbons-Hawking effect

The Gibbons-Hawking effect (after Gary Gibbons and Stephen Hawking ) states that every solution of Einstein's field equations that has a causal horizon can be assigned a temperature ; the causal horizon extends the concept of the event horizon from black holes to cosmological dimensions; it is the area in space-time beyond which events can no longer influence the observer.

The example of an event horizon was known earlier in the theory of black holes, where Jacob Bekenstein and Hawking assigned a temperature and thus an entropy to the surface of such a horizon in the early 1970s . In the case of Schwarzschild spacetime this is e.g. B. the temperature of a black hole of the mass , where ${\displaystyle T}$ ${\displaystyle M}$

${\displaystyle T\sim M^{-1}.}$

Hawking gave this temperature a physical interpretation in 1975 through the Hawking radiation .

An example of a causal horizon from cosmology is De-Sitter spacetime . Reference is made to the particle horizon, the maximum distance a particle could have traveled since the beginning of the universe . In this case the temperature is proportional to the Hubble parameter : ${\displaystyle T}$ ${\displaystyle H}$

${\displaystyle T\sim H.}$

Remarks

1. ^ Gary Gibbons, Stephen Hawking: Cosmological Event Horizons, Thermodynamics, and Particle Creation In: Physical Review D. 15, 1977, pp. 2738-2751.