Timeline for What is so problematic in the information paradox?
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| Jul 23, 2021 at 12:41 | comment | added | Andrew | @Jagerber48 The problem is that you can calculate what the state is within the effective field theory of gravity, and the state is exactly thermal, and not a highly entangled state. It's not enough to simply state in words this result is wrong, one has to provide a rigorous argument that explains why the original calculation is wrong (if it is). Here's Hawking's original paper on the paradox, which is well worth reading: journals.aps.org/prd/abstract/10.1103/PhysRevD.14.2460 | |
| Jul 23, 2021 at 12:38 | comment | added | Andrew | @GiorgioP There is a well-developed framework known as "the effective field theory of gravity" which can consistently treat gravity as an effective quantum theory that applies when deviations from a known background spacetime are small. This is the setting for the information loss paradox. One possible explanation is that the effective field theory framework does not apply -- but as I said above it's not enough to simply say these words, one needs to explain why it doesn't apply, which is not so easy because according to normal rules of effective field theory there's nothing obviously wrong. | |
| Jul 23, 2021 at 12:35 | comment | added | Andrew | @AndrewSteane There is a horizon in Rindler space. If you trace over the parts of Hilbert space outside of the Rindler horizon, then you do indeed get a mixed state, just as in a black hole background. In this case, there is no problem because we know in reality all that's happened is that we took a trace over a subset of the degrees of freedom, which are entangled with the degrees of freedom in our Rindler wedge. The difference with the black hole case is that the black hole evaporates. So the information is really lost (apparently), as opposed to simply missing in our calculation. | |
| Jul 22, 2021 at 14:35 | comment | added | Jagerber48 | Only seems like a "paradox" if there is some strong reason to cling to the notion that Hawking radiation MUST be a non-pure state.. | |
| Jul 22, 2021 at 14:34 | comment | added | Jagerber48 | I've never seen Hawking's calculation that Hawking radiation is thermal. But what is the big problem with saying Hawking radiation isn't thermal, and is rather a highly entangled many-body quantum state that 'looks' thermal when you don't know the details of the state? My understanding is that the generic many-body state is this way (for example electrons in a metal). | |
| Jul 22, 2021 at 13:36 | comment | added | GiorgioP-DoomsdayClockIsAt-90 | Everything in this argument would go smoothly if we had a proper quantum theory in curved spacetimes. Do we have it? As far as I know, work is in progress. Missing that, the whole argument should be taken a purely speculative, IMHO. | |
| Jul 22, 2021 at 9:58 | comment | added | Andrew Steane | When things accelerate and the Unruh effect takes place, is this a unitary process? | |
| Jul 15, 2021 at 21:37 | history | edited | Andrew | CC BY-SA 4.0 |
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| Jul 15, 2021 at 13:51 | vote | accept | CommunityBot | ||
| Jul 15, 2021 at 3:28 | history | answered | Andrew | CC BY-SA 4.0 |