# Effective field theory, black hole evaporation, firewalls

1. Jul 22, 2013

### atyy

Arkani-Hamed, Dubovsky, Nicolis, Trincherini, and Villadoro argue in section 2.2 of A Measure of de Sitter Entropy and Eternal Inflation that the effective field theory description of black hole evaporation fails after a time tev, even though the curvatures are small.

Almheiri, Marolf, Polchinski, and Sully argue for firewalls after Page time in Black Holes: Complementarity or Firewalls?.

Is tev the same as Page time, and is the AMPS Firewall argument related to ADTV's argument for the breakdown of effective field theory?

2. Jul 24, 2013

### fzero

The Page time seems to be $t_P = 7 t_\mathrm{ev} /8$, so they are essentially the same. AMPS refer to Giddings in their discussion of the validity of EFT. In Giddings 1201.1037, the Arkani-Hamed et al paper is confined to a footnote on page 17. I haven't understood the arguments well enough to compare them, but it seems like something interesting to look at.

3. Jul 24, 2013

### Ben Niehoff

Also check out some of Andrea Puhm's papers,

http://arxiv.org/abs/1210.6996
http://arxiv.org/abs/1208.3468
http://arxiv.org/abs/1208.2026

where she argues that violation of effective field theory should happen before the Page time (in fact, from the moment the black hole forms).

Personally, I'm not sure whether I believe in this distinction between "old" and "young" black holes. But there are still loads of details to be worked out, so it's hard to say.

4. Jul 24, 2013

### atyy

I guess what's different about Arkani-Hamed et al's argument is that they think they are giving the orthodox argument, citing Maldacena's Eternal Black Holes in AdS, whereas AMPS believes they are giving an unorthodox argument.

I looked at Andrea Puhm's http://arxiv.org/abs/1210.6996 , her Fig 1b is very similar to Arkani-Hamed et al's (ADNTV) Fig. 2, ie. the failure of effective field theory is big only after Page time. So I guess AMPS must be claiming something stronger or more specific than that - the firewall for all observers, whereas Puhm argues that for low energy observers nothing dramatic happens. ADNTV and Puhm both argue for some form of complementarity.

Last edited: Jul 24, 2013
5. Jul 24, 2013

### Haelfix

The Page time is the point where a black hole has lost half of its entropy, whereas the point ADNT are talking about is where effective field theory completely breaks down (where it is no longer corrected by small effects of order e^-S). These two things are not necessarily the same thing I don't think, although parametrically they seem to be close and the heuristic order of magnitude calculations done in the ADNT paper are not powerful enough to provide a more precise estimate.

In fact, I was under the impression AMPS implicitly assume that effective field theory is still valid after the Page time (but before the evaporation time) and then proceed to derive a contradiction.