From vacuum fluctuations across an event horizon to long distance correlations

Understand

We study the stress energy two-point function to show how short distance correlations across the horizon transform into correlations among asymptotic states, for the Unruh effect, and for black hole radiation.

• In the first case the transition is caused by the coupling to accelerated systems.
• In the second, the transition is more elusive and due to the change of the geometry from the near horizon region to the asymptotic one.
• The gradual transition is appropriately described by using affine coordinates.