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Does Hawking radiation assumes that general relativity works perfectly, inside black holes, or on the event horizon?

Could someone please tell me the exact statements made in describing hawking radiation? ( Before we apply the math).

Would the concept of hawking radiation be moot if General relativity somehow failed, inside a black hole, since at this point we only have a theoretical model for a black hole?

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    $\begingroup$ Possible duplicate of An explanation of Hawking Radiation $\endgroup$ – John Rennie Sep 20 '17 at 15:21
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    $\begingroup$ Yes. Hawking's calculation takes spacetime to be curved in the way described by GR, and it uses this fixed geometry to do the quantum field theory calculation. So it does assume GR holds. $\endgroup$ – John Rennie Sep 20 '17 at 16:12
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    $\begingroup$ The calculation Hawking himself did assumes that GR holds exactly everywhere. However it is really only the presence of a horizon that causes radiation to be observed. So even variants on GR like Brans-Dicke would still predict radiation as long as a horizon is present. GR would have to fail so badly that there was no event horizon for the Hawking radiation to fail to exist. $\endgroup$ – John Rennie Sep 20 '17 at 17:16
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    $\begingroup$ For close voters - I don't believe this is a duplicate, as it's asking for the assumptions behind hawking radiation, not a description of it. $\endgroup$ – heather Sep 20 '17 at 20:29
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    $\begingroup$ We have no reason to doubt that GR works under the conditions that are present at the event horizon of a black hole. The conditions under which we expect GR to fail are those in which the curvature of spacetime was comparable to the inverse of the Planck scale. Those are conditions that apply near the singularity, not at the horizon. $\endgroup$ – Ben Crowell Sep 20 '17 at 23:08
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First let me direct you to An explanation of Hawking Radiation where I have attempted an accurate but relatively accessible explanation of the mechanism for Hawking radiation.

To address your specific points: Hawking's original calculation assumed that general relativity gives the correct description of the spacetime every inside and outside the black hole event horizon. He used quantum field theory in the curved spacetime predicted by GR to perform his calculations.

However the key feature that causes the radiation is the presence of a horizon, so alternatives to general relativity like Brans-Dicke theory also predict Hawking radiation as long as a horizon is present. General relativity would have to fail so badly that no event horizon exists for there to be no Hawking radiation.

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