On Tuesday, March 12, 2019 at 4:38:24 PM UTC-6, John Clark wrote:
>
> On Tue, Mar 12, 2019 at 8:41 AM Lawrence Crowell <goldenfield...@gmail.com
> <javascript:>> wrote:
>
> > The time it takes a black hole (BH) to quantum decay completely is
>> proportional to the cube of the mass, which means the black hole has
>> emitted half its mass in 7/8ths of its expected duration. This means
>> that when a black hole is reduced to half of its original mass the
>> bipartite entangled photons with the BH emitted a long time ago, for a
>> solar mass black hole some 10^{67}years, are now entangled with not only
>> the BH, but with newly emitted photons. This is a big problem. This is
>> telling us there is a difficulty in making entanglement entropy fit with
>> the Bekenstein bound and that bipartite entanglements are transformed into
>> tripartite entanglements. This means quantum unitarity fails. This is not
>> something people are willing to abandon so easily, so what AMPS [Almheiri,
>> D. Marolf, J. Polchinski, J. Sully, "Black holes: complementarity or
>> firewalls?". JHEP. $\bf 2$, (2013). arXiv:1207.3123] proposed was that
>> instead of losing quantum unitarity maybe the equivalence principle of
>> general relativity fails. This means the BH becomes a sort of naked
>> singularity at the horizon, called the firewall, where anything that enters
>> is just demolished or "burned up" as it would in the interior of a BH.
>>
>
> First of all thanks a lot for taking the time to write a very interesting
> post. I'm trying to understand why the firewall is hot. I understand that
> if I'm hovering just above the event horizon in a super powerful rocket
> time would slow down so much I'd be able to observe the Black Hole evaporate
> , even if it took 10^ 67 years for a observer far from the Black Hole to
> me it would only take a few seconds, and that means the Hawking Radiation
> would burn me to a crisp. And I understand that until very recently
> everybody said that if rather than hovering I was freely falling I wouldn't
> even notice I've passed the Event Horizon, but if the Equivalence Principle
> breaks down at that point perhaps I would notice it after all. Is that a
> productive way to think about the Firewall? I've heard some say it's the
> breaking of entanglement needed to avoid tripartite entanglements and
> preserving
> quantum unitarity that causes the Firewall, but the connection between
> heat and broken entanglement is not intuitively obvious to me.
>
What you describe is an amplification of the Hawking radiation by the Unruh
effect. This can be thought of as due to the huge time dilation where the
accelerated observer's clock is so slow relative to the outside that a few
seconds can be billions of years out in asymptotic infinity. This is not
the same as the firewall. The firewall is really an artificial
construction. In order to save quantum unitarity one can think the
equivalence principle is lost and nothing makes it across the horizon. This
means there would be some way that nothing can enter or leave the black
hole, which is often thought of as the firewall.
>
>
>> > This provides me with the motivation at least to think that spacetime
>> and quantum information are much the same.
>>
>
> I think if that could be shown to be less wrong than current ideas it
> would be one of the greatest triumphs in the history of science.
>
Verlinde and Verlinde in a paper in 2015 argued there must be an open world
physics. I tend to agree. The way out as I see it is that if we have
complete quantum gravitation the back reaction of the metric is then a
quantum mechanical process that emits gravitons. The transfer from a
bipartite entanglement to a tripartite entanglement then need not happen.
There is simply an entanglement swap with gravitons that carry BMS
symmetiries or charges.
>
>
>> > It also relates to quantum error correction codes and the Hamming
>> distance. If you have a library where books are not reshelved regularly
>> then when about half the books become irregularly stacked off their duly
>> appointed shelves it becomes much harder the reshelve them. This is a limit
>> on an error correction, and the Page time or firewall is related to this.
>>
>
> I can see how that might cause a big jump in entropy when the Black Hole
> reaches the Page time, but the universe isn't old enough for any Black Hole
> to have reached the Page time so I don't see the connection to a ultra hot
> firewall. What causes the heat?
>
> John K Clark
>
The only way I can imagine a large black hole with a firewall is if the
firewall is some extremal condition. For the Kerr solution the inner and
outer horizons merge for angular momentum parameter equal to the mass. The
surface of the black hole is then actually zero temperature. This would
then mean gravitation has a chirality where Hawking radiation has a
preferred handedness and the remaining black hole is left with opposite
angular momentum. Charge might play a role as well. This has other
problems, but it would at least connect the so called firewall to BPS
charges of black hiles.
I do think the firewall is simply an obstruction that needs to be solved. I
doubt it actually exists.
LC
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