# Situation after Saini & Stojkovic's paper on unitarity in gravitational collapse and non-formation of black holes?

In their paper, Anshul Saini and Dejan Stojkovic [1] claimed that by calculations it is possible to demonstrate that in a gravitational collapse of a disk, an event horizon is never made for a far observer. Some "radiation" is emitted in the moment of collapse and when the collapse gets close to forming a black hole the "radiation" is very similar to Hawking radiation. However, the emitted radiation "turns down" the collapse in such a way that as time goes to infinity we get only "radiation."

I'm concerned about the generality of this result. Does this mean that black holes are some sort of approximation for small time intervals (when compared with the mass), in analogy with any other resonance? For example, the eigenvectors of a hydrogen atom of $1p^2$ is a resonance via interactions with EM vacuum. Is the black hole an analogue of a $1p^2$ state in this sense?

[1] Radiation from a collapsing object is manifestly unitary, Anshul Saini, Dejan Stojkovic (SUNY, Buffalo), Phys.Rev.Lett. 114 (2015) 111301

[2] There is a guide made by the author at this blog.

• @innisfree, thanks for the edition. I'm only changing the - free-fall - for - far - , because is the far observer indeed. The one that sees Schwarzschild metric. – Nogueira Apr 18 '15 at 18:53
• oops sorry i thought it was a typo – innisfree Apr 18 '15 at 19:25
• Actually what they want to demonstrate is that in the vicinity of a collapsing object what happens to quantum field information as the singularity starts to form. In other words what would happen to infalling matter and the then ejected hawking rafiation and is the information about a quantum state preserved between the two. I actually sat in on a preliminary talk give by Anshul as we attend he same university and are in the same department – Triatticus Apr 18 '15 at 20:14
• But in reference 2 stated that no singularity is formed. – Nogueira Apr 18 '15 at 20:30