I'm trying to understand the ideas in this paper at a nontechnical level: Laura Mersini-Houghton, "Backreaction of Hawking Radiation on a Gravitationally Collapsing Star I: Black Holes?," http://arxiv.org/abs/1406.1525 She says: This work investigates the backreaction of Hawking radiation on the interior of a gravitationally collapsing star, in a Hartle-Hawking initial vacuum. It shows that due to the negative energy Hawking radiation in the interior, the collapse of the star stops at a finite radius, before the singularity and the event horizon of a black hole have a chance to form. I'm just baffled by this claim. For an astrophysical black hole, the Hawking radiation is the most incredibly tenuous thing you could possibly imagine -- utterly undetectable by any foreseeable technology. How, then, can it cause a back-reaction so vigorous as to prevent the formation of an event horizon? In general, I can't overcome a feeling of disbelief in semiclassical gravity. It seems like they get all kinds of gee-whiz results that are just clearly not reasonable, and that should be interpreted simply as a sign that semiclassical gravity doesn't work. In particular, semiclassical gravity seems to predict spectacular stuff happening near the event horizons of black holes. They even get divergences that need to be renormalized away. But for a black hole of mass M, I can make the curvature of spacetime at the horizon as small as desired by making M big enough. Therefore I have a hard time believing any prediction that something special happens at the event horizon, if the prediction is independent of M.