I Experimental evidence of the existence of an event horizon

Bosko
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Is there experimental evidence of the existence of an Event Horizon ?
There is good enough experimental evidence for the existence of a Photon Sphere.
Is there clear unequivocal experimental evidence for the existence of an Event Horizon ?
 
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"Good enough"? The lIGO data is probably providing the best evidence. It depends on what EH feature you want tested.
 
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There is no direct evidence of the existence of an event horizon, and there never can be. There is evidence of EM radiation signatures from inside the photon sphere which is consistent with GR. Localising GW emission is a somewhat dubious thing, but the region inside the photon sphere contributes to our models of emission, so they test that region.
 
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Thread closed temporarily for Moderation...
 
The OP question has been answered. Thread will remain closed.
 
From $$0 = \delta(g^{\alpha\mu}g_{\mu\nu}) = g^{\alpha\mu} \delta g_{\mu\nu} + g_{\mu\nu} \delta g^{\alpha\mu}$$ we have $$g^{\alpha\mu} \delta g_{\mu\nu} = -g_{\mu\nu} \delta g^{\alpha\mu} \,\, . $$ Multiply both sides by ##g_{\alpha\beta}## to get $$\delta g_{\beta\nu} = -g_{\alpha\beta} g_{\mu\nu} \delta g^{\alpha\mu} \qquad(*)$$ (This is Dirac's eq. (26.9) in "GTR".) On the other hand, the variation ##\delta g^{\alpha\mu} = \bar{g}^{\alpha\mu} - g^{\alpha\mu}## should be a tensor...
OK, so this has bugged me for a while about the equivalence principle and the black hole information paradox. If black holes "evaporate" via Hawking radiation, then they cannot exist forever. So, from my external perspective, watching the person fall in, they slow down, freeze, and redshift to "nothing," but never cross the event horizon. Does the equivalence principle say my perspective is valid? If it does, is it possible that that person really never crossed the event horizon? The...

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