Re: Inside Black Holes

[Lawrence Crowell]

On Sunday, January 14, 2018 at 5:54:50 PM UTC-6, John Clark wrote:
>
> Hi Lawrence, thanks for a very interesting post.
>
> ​> ​
>> The vacuum is filled with virtual pairs of fields. With a black hole the 
>> gravity field causes one of these pairs to fall into the black hole and the 
>> other to escape. This means the quantum particle or photon that escapes as 
>> Hawking radiation is entangled with the pair that falls into the black 
>> hole, and so this means Hawking radiation is entangled with the black hole. 
>> So at first blush there seems to be no problem. However, if we think of a 
>> thermal cavity heated to high temperature photons that escape are entangled 
>> with quantum states of atoms composing the cavity. Once the entanglement 
>> entropy reaches a maximum at half the energy released the subsequent 
>> photons released are entangled with prior photons released. This would hold 
>> with black holes as well, but because of the virtual pair nature of this 
>> radiation it means Hawking radiation previously emitted in a bipartite 
>> entanglement are now entangled not just with the black hole, but with more 
>> recently emitted radiation as well. This means a bipartite entanglement is 
>> transformed into a tripartite entanglement. Such transformations are not 
>> permitted by quantum unitary evolution. This is called quantum monogamy 
>> requirement, and what this suggests is unitarity fails. To prevent the 
>> failure of quantum mechanics some proposed a firewall that violates the 
>> equivalency principle. This is called a firewall.
>>
> The firewall occurs when half the possible radiation is emitted, which is 
>> also the Page time.
>>
>
> You clearly explain why after half the Black Hole has evaporated further 
> radiated photons would, on the face of it, be entangled with 3 things, and 
> if that is forbidden by quantum mechanics then one of those entanglements 
> would need to be broken
> ​.​
>  
> ​But
>  what I don't understand is why breaking the 
> ​quantum ​
> link with the Black Hole would make things hot.
> ​ ​
> Joseph Polchinski, they guy who came up with the firewall idea said:
>
>  
>
> *“It’s a violent process, like breaking the bonds of a molecule, and it 
> releases energy​.​The energy generated by severing lots of twins would be 
> enormous. The event horizon would literally be a ring of fire that burns 
> anyone falling through”*
> ​But why? Why would breaking quantum entanglement ​release energy and 
> produce heat, what does one have to do with the other? 
>   
>  
>
>> ​> ​
>> This also corresponds to the failure of a quantum error correction code.
>>
>
> ​
> Please correct me if I'm wrong but I think you're saying before half the 
> Black Hole has evaporated you could hypothesize than although it looks 
> random maybe information i
> ​s​
> encoded in the Hawking radiation in some very elaborate way, but after 
> that it would be impossible even in theory. A connection between Black 
> Holes and quantum error correcting codes is really intriguing! 
> ​I take it 
> you think the information about the stuff that formed the Black Hole is 
> truly lost
> ​.​
> ​Or is there some way out?​
>  
> ​
>
>  John K Clark​
>

The firewall is a bit of a phenomenological "patch." If the equivalence 
principle is violated so as to prevent any passage of quanta in or out of 
the black hole then in some ways the singularity of the black hole appears 
where the horizon should be. The singularity would in some ways be similar 
to the singularity that occurs for an extremal black hole, where it 
communicates no information to the outside world. The idea is in some ways 
a bit odd, and it really is meant to illustrate an obstruction to our 
understanding on how quantum mechanics works with gravitation.

LC 

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Re: Inside Black Holes

[Lawrence Crowell]

On Sunday, January 14, 2018 at 5:02:16 PM UTC-6, Brent wrote:
>
>
>
> On 1/14/2018 8:24 AM, Lawrence Crowell wrote:
>
> On Sunday, January 14, 2018 at 9:25:40 AM UTC-6, John Clark wrote: 
>>
>> On Sun, Jan 14, 2018 at 1:40 AM, Brent Meeker  
>> wrote:
>>
>> ​>> ​
 ​I think that would be true if, as in your example, the observer were 
 freely falling into the Black Hole, but if I was hovering just outside the 
 Event Horizon in a super powerful spaceship I could observe the Black Hole 
 evaporating in just a few minutes
>>>
>>>  
>>
>> ​> ​
>>> That seems doubtful since Hawking radiation has its peak wavelength on 
>>> the order of the diameter of the black hole and originates in the vicinity, 
>>> i.e. within a few radii of the black hole, not "at the event horizon". 
>>>  ​
>>>
>>
>> Most Hawking radiation originates where the tidal forces are the 
>> greatest, and that would be at the Event Horizon. The closer I hover above 
>> the Event Horizon the slower my clock will tick, so if I hover close enough 
>> I can watch the entire Black Hole evaporate away in just a few minutes by 
>> my clock even though for you back on Earth that would take a billion 
>> trillion years or so. The thing that causes Black Hole evaporation is 
>> Hawking radiation, so if I observe one I'm going to have to observe the 
>> other, although "observe" may not be the right word, "incinerate" might be 
>> better.
>>
>> ​ ​
>> John K Clark
>>
>
> Where the Hawking occurs is a tad funny. For a distant observer the 
> radiation will appear to occur at about 4GM/c^2 from the horizon that has a 
> radius of 2GM/c^2. This does correspond to the wavelength of the radiation 
> and so forth. However, if you are on an accelerated frame stationary with 
> respect to the horizon the radiation occurs closer to the horzion. In the 
> limit you reach Planck acceleration ~ 10^{51}m/s^2 the radiation occurs a 
> Planck length above the horizon. So what is going on?
>
>
> So how do you see it if you're free-falling in?  Do you see it as blue 
> shifted as you approach the BH at increasing speed, but it diminishes in 
> the region between 4GM/c^2 and 2GM/c^2 as you fall toward the event horizon?
>
> Brent
>

A free falling observer would witness Hawking radiation flux peak around 
4GM/c^2, which corresponds roughly to the peak of the blackbody curve. A 
free falling observer would reach this region from asymptopia with a gamma 
factor 

Γ = 1/sqrt{1 - v^2/c^2}

for v^2 ~ 2GM/r, and r = 4GM/c^2 and so Γ = 1.41. This would give the blue 
shift factor or the frequency of radiation would be adjusted by that 
multiplicative factor.

LC
 

>
>
> If you observe an object fall towards a black hole it will by the tortoise 
> coordinate appear to hover just above the horizon. Conversely the quantum 
> fields and ultimately quantum bits from that object will appear outside the 
> black hole. In effect they appear at two places at the same time! What we 
> think of as an event in spacetime as a unique specifier of the state of a 
> system is an approximation. With quantum field theory there has been a lot 
> of stuff to remove nonlocality, such as Wightman conditions of commutators 
> of observables. Quantum nonlocality plays a subtle role and in high energy 
> experimental physics its physical influence is considered negligible. 
> However, the time dilation physics of a black hole amplifies these nonlocal 
> influences so they can no longer be ignored. 
>
> LC
>
>

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Re: Inside Black Holes

[John Clark]

Hi Lawrence, thanks for a very interesting post.

​> ​
> The vacuum is filled with virtual pairs of fields. With a black hole the
> gravity field causes one of these pairs to fall into the black hole and the
> other to escape. This means the quantum particle or photon that escapes as
> Hawking radiation is entangled with the pair that falls into the black
> hole, and so this means Hawking radiation is entangled with the black hole.
> So at first blush there seems to be no problem. However, if we think of a
> thermal cavity heated to high temperature photons that escape are entangled
> with quantum states of atoms composing the cavity. Once the entanglement
> entropy reaches a maximum at half the energy released the subsequent
> photons released are entangled with prior photons released. This would hold
> with black holes as well, but because of the virtual pair nature of this
> radiation it means Hawking radiation previously emitted in a bipartite
> entanglement are now entangled not just with the black hole, but with more
> recently emitted radiation as well. This means a bipartite entanglement is
> transformed into a tripartite entanglement. Such transformations are not
> permitted by quantum unitary evolution. This is called quantum monogamy
> requirement, and what this suggests is unitarity fails. To prevent the
> failure of quantum mechanics some proposed a firewall that violates the
> equivalency principle. This is called a firewall.
>
The firewall occurs when half the possible radiation is emitted, which is
> also the Page time.
>

You clearly explain why after half the Black Hole has evaporated further
radiated photons would, on the face of it, be entangled with 3 things, and
if that is forbidden by quantum mechanics then one of those entanglements
would need to be broken
​.​

​But
 what I don't understand is why breaking the
​quantum ​
link with the Black Hole would make things hot.
​ ​
Joseph Polchinski, they guy who came up with the firewall idea said:



*“It’s a violent process, like breaking the bonds of a molecule, and it
releases energy​.​The energy generated by severing lots of twins would be
enormous. The event horizon would literally be a ring of fire that burns
anyone falling through”*
​But why? Why would breaking quantum entanglement ​release energy and
produce heat, what does one have to do with the other?



> ​> ​
> This also corresponds to the failure of a quantum error correction code.
>

​
Please correct me if I'm wrong but I think you're saying before half the
Black Hole has evaporated you could hypothesize than although it looks
random maybe information i
​s​
encoded in the Hawking radiation in some very elaborate way, but after that
it would be impossible even in theory. A connection between Black Holes and
quantum error correcting codes is really intriguing!
​I take it
you think the information about the stuff that formed the Black Hole is
truly lost
​.​
​Or is there some way out?​

​

 John K Clark​

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Re: Inside Black Holes

[Brent Meeker]

On 1/14/2018 8:24 AM, Lawrence Crowell wrote:

On Sunday, January 14, 2018 at 9:25:40 AM UTC-6, John Clark wrote:

On Sun, Jan 14, 2018 at 1:40 AM, Brent Meeker >wrote:

​>> ​
​I think that would be true if, as in your example, the
observer were freely falling into the Black Hole, but if I
was hovering just outside the Event Horizon in a super
powerful spaceship I could observe the Black Hole
evaporating in just a few minutes

​> ​
That seems doubtful since Hawking radiation has its peak
wavelength on the order of the diameter of the black hole and
originates in the vicinity, i.e. within a few radii of the
black hole, not "at the event horizon".
 ​


Most Hawking radiation originates where the tidal forces are the
greatest, and that would be at the Event Horizon. The closer I
hover above the Event Horizon the slower my clock will tick, so if
I hover close enough I can watch the entire Black Hole evaporate
away in just a few minutes by my clock even though for you back on
Earth that would take a billion trillion years or so. The thing
that causes Black Hole evaporation is Hawking radiation, so if I
observe one I'm going to have to observe the other, although
"observe" may not be the right word, "incinerate" might be better.

​ ​
John K Clark


Where the Hawking occurs is a tad funny. For a distant observer the 
radiation will appear to occur at about 4GM/c^2 from the horizon that 
has a radius of 2GM/c^2. This does correspond to the wavelength of the 
radiation and so forth. However, if you are on an accelerated frame 
stationary with respect to the horizon the radiation occurs closer to 
the horzion. In the limit you reach Planck acceleration ~ 10^{51}m/s^2 
the radiation occurs a Planck length above the horizon. So what is 
going on?


So how do you see it if you're free-falling in?  Do you see it as blue 
shifted as you approach the BH at increasing speed, but it diminishes in 
the region between 4GM/c^2 and 2GM/c^2 as you fall toward the event horizon?


Brent



If you observe an object fall towards a black hole it will by the 
tortoise coordinate appear to hover just above the horizon. Conversely 
the quantum fields and ultimately quantum bits from that object will 
appear outside the black hole. In effect they appear at two places at 
the same time! What we think of as an event in spacetime as a unique 
specifier of the state of a system is an approximation. With quantum 
field theory there has been a lot of stuff to remove nonlocality, such 
as Wightman conditions of commutators of observables. Quantum 
nonlocality plays a subtle role and in high energy experimental 
physics its physical influence is considered negligible. However, the 
time dilation physics of a black hole amplifies these nonlocal 
influences so they can no longer be ignored.


LC
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Re: Inside Black Holes

[Lawrence Crowell]

On Sunday, January 14, 2018 at 1:00:48 PM UTC-6, Brent wrote:
>
>
>
> On 1/14/2018 5:30 AM, Lawrence Crowell wrote:
>
> On Saturday, January 13, 2018 at 6:30:33 PM UTC-6, Brent wrote: 
>>
>>
>>
>> On 1/13/2018 2:44 PM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Saturday, January 13, 2018 at 2:59:00 PM UTC-7, Brent wrote: 
>>>
>>> Classically, the radiation isn't "trapped"; it goes to the singularity 
>>> (what the QM does? dunno).  The inflowing radiation is just that starlight 
>>> that falls on the event horizon...which is not particularly bright.
>>>
>>> Brent
>>>
>>
>> I'm referring to the INTERIOR of the BH. 
>>
>>
>> So am I.
>>
>> If the radiation is trapped inside, the environment is likely hot and 
>> bright. 
>>
>>
>> Or it's absorbed by the singularity...or whatever is really there.  
>> There's not reasonable picture in which it is "trapped inside" and is 
>> flying around inside the black hole.  Inside a Schawarzschild black hole 
>> "the singularity" is on the future of every world line, including null 
>> ones.  Inside a Kerr-Newman black hole it may be possible to miss "the 
>> singularity" but then it appears to connect to a another spacetime.  Both 
>> of these are solutions for eternal black holes, so when it's a black hole 
>> that forms and then evaporates the solutions may not hold.  However, except 
>> near "the singularity" the analyses would hold and so except for within 
>> nanoseconds of "the singularity" all photons are going to be traveling 
>> toward "the singularity" and not flying around willy-nilly, "trapped" in 
>> the black hole.  They can't turn around because that direction is the past.
>>
>> Brent
>>
>
> This of course gets a bit weird. I put in a short Penrose diagram of the 
> Kerr-Newman black hole. Matter on the right I region will cross the r_+ 
> horizon and fall into the III spacelike region. From there it must cross 
> the interior horizon at r_-. Now there are two funny points here. The first 
> is whether the r_- horizon is a mass inflation singularity and prevents any 
> information from crossing. 
>
>
> But have you seen this paper:
>
> Mass inflation inside black holes revisited
> Vyacheslav I. Dokuchaev
> (Submitted on 1 Sep 2013 (v1), last revised 21 Feb 2014 (this version, v4))
> The mass inflation phenomenon implies that black hole interiors are 
> unstable due to a back-reaction divergence of the perturbed black hole mass 
> function at the Cauchy horizon. Weak point in the standard mass inflation 
> calculations is in a fallacious using of the global Cauchy horizon as a 
> place for the maximal growth of the back-reaction perturbations instead of 
> the local inner apparent horizon. It is derived the new spherically 
> symmetric back-reaction solution for two counter-streaming light-like 
> fluxes near the inner apparent horizon of the charged black hole by taking 
> into account its separation from the Cauchy horizon. In this solution the 
> back-reaction perturbations of the background metric are truly the largest 
> at the inner apparent horizon, but, nevertheless, remain small. The back 
> reaction, additionally, removes the infinite blue-shift singularity at the 
> inner apparent horizon and at the Cauchy horizon.
>  (or arXiv:1309.0224v4 [gr-qc] for this version)
>
>
> Brent
>

I will take a look at this as soon as possible. I always have quite a stack 
of stuff that I need to read. A part of this of course is that we are not 
certain about the black hole interior. The eternal solutions of Einstein's 
field equations are mathematical idealizations. What occurs physically is 
more difficult to understand because the birth and death of a black hole is 
a topological change, a sort of cobordism on spacetime. General relativity 
does not handle this.

LC
 

>
> The other is a spatial surface in the cosmology region I has two 
> alternatives that connect to two inner timelike regions IV and V. This 
> illustrates some possible monodromy associated with the interior of a black 
> hole. 
>
> The prospect of this monodromy raises the question of whether these inner 
> regions IV and V are in some ways entangled with quantum states in the 
> exterior region. There then might be some physical region there instead of 
> just this being a mathematical idealization. If so this interior region is 
> filled with radiation and particles on closed timelike curves cycling 
> around the singularity. The real question of course is whether t

Re: Inside Black Holes

[Brent Meeker]

On 1/14/2018 5:30 AM, Lawrence Crowell wrote:

On Saturday, January 13, 2018 at 6:30:33 PM UTC-6, Brent wrote:



On 1/13/2018 2:44 PM, agrays...@gmail.com  wrote:



On Saturday, January 13, 2018 at 2:59:00 PM UTC-7, Brent wrote:

Classically, the radiation isn't "trapped"; it goes to the
singularity (what the QM does? dunno).  The inflowing
radiation is just that starlight that falls on the event
horizon...which is not particularly bright.

Brent


I'm referring to the INTERIOR of the BH.


So am I.


If the radiation is trapped inside, the environment is likely hot
and bright.


Or it's absorbed by the singularity...or whatever is really
there.  There's not reasonable picture in which it is "trapped
inside" and is flying around inside the black hole.  Inside a
Schawarzschild black hole "the singularity" is on the future of
every world line, including null ones. Inside a Kerr-Newman black
hole it may be possible to miss "the singularity" but then it
appears to connect to a another spacetime.  Both of these are
solutions for eternal black holes, so when it's a black hole that
forms and then evaporates the solutions may not hold.  However,
except near "the singularity" the analyses would hold and so
except for within nanoseconds of "the singularity" all photons are
going to be traveling toward "the singularity" and not flying
around willy-nilly, "trapped" in the black hole. They can't turn
around because that direction is the past.

Brent


This of course gets a bit weird. I put in a short Penrose diagram of 
the Kerr-Newman black hole. Matter on the right I region will cross 
the r_+ horizon and fall into the III spacelike region. From there it 
must cross the interior horizon at r_-. Now there are two funny points 
here. The first is whether the r_- horizon is a mass inflation 
singularity and prevents any information from crossing.


But have you seen this paper:

Mass inflation inside black holes revisited
Vyacheslav I. Dokuchaev
(Submitted on 1 Sep 2013 (v1), last revised 21 Feb 2014 (this version, v4))
The mass inflation phenomenon implies that black hole interiors are 
unstable due to a back-reaction divergence of the perturbed black hole 
mass function at the Cauchy horizon. Weak point in the standard mass 
inflation calculations is in a fallacious using of the global Cauchy 
horizon as a place for the maximal growth of the back-reaction 
perturbations instead of the local inner apparent horizon. It is derived 
the new spherically symmetric back-reaction solution for two 
counter-streaming light-like fluxes near the inner apparent horizon of 
the charged black hole by taking into account its separation from the 
Cauchy horizon. In this solution the back-reaction perturbations of the 
background metric are truly the largest at the inner apparent horizon, 
but, nevertheless, remain small. The back reaction, additionally, 
removes the infinite blue-shift singularity at the inner apparent 
horizon and at the Cauchy horizon.

 (or arXiv:1309.0224v4 [gr-qc] for this version)


Brent

The other is a spatial surface in the cosmology region I has two 
alternatives that connect to two inner timelike regions IV and V. This 
illustrates some possible monodromy associated with the interior of a 
black hole.


The prospect of this monodromy raises the question of whether these 
inner regions IV and V are in some ways entangled with quantum states 
in the exterior region. There then might be some physical region there 
instead of just this being a mathematical idealization. If so this 
interior region is filled with radiation and particles on closed 
timelike curves cycling around the singularity. The real question of 
course is whether there is some entanglement of states between the 
regions I and II, two timelike regions that may have multiverse 
considerations, and whether the ambiguity of how one pushes a 
spacelike surface forwards means there are also entanglements in the 
two interior regions.


LC

<https://lh3.googleusercontent.com/-LFRNH9NhvUg/WltY3b6FPtI/DNI/nXma0OO04KQPjLnzq9W3_Jv45DnffpcfgCLcBGAs/s1600/Penrose%2Bdiagram%2Bfor%2BRN%2Bwith%2B2%2Bspatial%2Bsurfaces.png>


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Re: Inside Black Holes

[Lawrence Crowell]

On Sunday, January 14, 2018 at 9:25:40 AM UTC-6, John Clark wrote:
>
> On Sun, Jan 14, 2018 at 1:40 AM, Brent Meeker  > wrote:
>
> ​>> ​
>>> ​I think that would be true if, as in your example, the observer were 
>>> freely falling into the Black Hole, but if I was hovering just outside the 
>>> Event Horizon in a super powerful spaceship I could observe the Black Hole 
>>> evaporating in just a few minutes
>>
>>  
>
> ​> ​
>> That seems doubtful since Hawking radiation has its peak wavelength on 
>> the order of the diameter of the black hole and originates in the vicinity, 
>> i.e. within a few radii of the black hole, not "at the event horizon".
>>  ​
>>
>
> Most Hawking radiation originates where the tidal forces are the greatest, 
> and that would be at the Event Horizon. The closer I hover above the Event 
> Horizon the slower my clock will tick, so if I hover close enough I can 
> watch the entire Black Hole evaporate away in just a few minutes by my 
> clock even though for you back on Earth that would take a billion trillion 
> years or so. The thing that causes Black Hole evaporation is Hawking 
> radiation, so if I observe one I'm going to have to observe the other, 
> although "observe" may not be the right word, "incinerate" might be better.
>
> ​ ​
> John K Clark
>

Where the Hawking occurs is a tad funny. For a distant observer the 
radiation will appear to occur at about 4GM/c^2 from the horizon that has a 
radius of 2GM/c^2. This does correspond to the wavelength of the radiation 
and so forth. However, if you are on an accelerated frame stationary with 
respect to the horizon the radiation occurs closer to the horzion. In the 
limit you reach Planck acceleration ~ 10^{51}m/s^2 the radiation occurs a 
Planck length above the horizon. So what is going on?

If you observe an object fall towards a black hole it will by the tortoise 
coordinate appear to hover just above the horizon. Conversely the quantum 
fields and ultimately quantum bits from that object will appear outside the 
black hole. In effect they appear at two places at the same time! What we 
think of as an event in spacetime as a unique specifier of the state of a 
system is an approximation. With quantum field theory there has been a lot 
of stuff to remove nonlocality, such as Wightman conditions of commutators 
of observables. Quantum nonlocality plays a subtle role and in high energy 
experimental physics its physical influence is considered negligible. 
However, the time dilation physics of a black hole amplifies these nonlocal 
influences so they can no longer be ignored. 

LC

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Re: Inside Black Holes

[John Clark]

On Sun, Jan 14, 2018 at 1:40 AM, Brent Meeker  wrote:

​>> ​
>> ​I think that would be true if, as in your example, the observer were
>> freely falling into the Black Hole, but if I was hovering just outside the
>> Event Horizon in a super powerful spaceship I could observe the Black Hole
>> evaporating in just a few minutes
>
>

​> ​
> That seems doubtful since Hawking radiation has its peak wavelength on the
> order of the diameter of the black hole and originates in the vicinity,
> i.e. within a few radii of the black hole, not "at the event horizon".
>  ​
>

Most Hawking radiation originates where the tidal forces are the greatest,
and that would be at the Event Horizon. The closer I hover above the Event
Horizon the slower my clock will tick, so if I hover close enough I can
watch the entire Black Hole evaporate away in just a few minutes by my
clock even though for you back on Earth that would take a billion trillion
years or so. The thing that causes Black Hole evaporation is Hawking
radiation, so if I observe one I'm going to have to observe the other,
although "observe" may not be the right word, "incinerate" might be better.

​ ​
John K Clark

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Re: Inside Black Holes

[Lawrence Crowell]

On Saturday, January 13, 2018 at 6:30:33 PM UTC-6, Brent wrote:
>
>
>
> On 1/13/2018 2:44 PM, agrays...@gmail.com  wrote:
>
>
>
> On Saturday, January 13, 2018 at 2:59:00 PM UTC-7, Brent wrote: 
>>
>> Classically, the radiation isn't "trapped"; it goes to the singularity 
>> (what the QM does? dunno).  The inflowing radiation is just that starlight 
>> that falls on the event horizon...which is not particularly bright.
>>
>> Brent
>>
>
> I'm referring to the INTERIOR of the BH. 
>
>
> So am I.
>
> If the radiation is trapped inside, the environment is likely hot and 
> bright. 
>
>
> Or it's absorbed by the singularity...or whatever is really there.  
> There's not reasonable picture in which it is "trapped inside" and is 
> flying around inside the black hole.  Inside a Schawarzschild black hole 
> "the singularity" is on the future of every world line, including null 
> ones.  Inside a Kerr-Newman black hole it may be possible to miss "the 
> singularity" but then it appears to connect to a another spacetime.  Both 
> of these are solutions for eternal black holes, so when it's a black hole 
> that forms and then evaporates the solutions may not hold.  However, except 
> near "the singularity" the analyses would hold and so except for within 
> nanoseconds of "the singularity" all photons are going to be traveling 
> toward "the singularity" and not flying around willy-nilly, "trapped" in 
> the black hole.  They can't turn around because that direction is the past.
>
> Brent
>

This of course gets a bit weird. I put in a short Penrose diagram of the 
Kerr-Newman black hole. Matter on the right I region will cross the r_+ 
horizon and fall into the III spacelike region. From there it must cross 
the interior horizon at r_-. Now there are two funny points here. The first 
is whether the r_- horizon is a mass inflation singularity and prevents any 
information from crossing. The other is a spatial surface in the cosmology 
region I has two alternatives that connect to two inner timelike regions IV 
and V. This illustrates some possible monodromy associated with the 
interior of a black hole. 

The prospect of this monodromy raises the question of whether these inner 
regions IV and V are in some ways entangled with quantum states in the 
exterior region. There then might be some physical region there instead of 
just this being a mathematical idealization. If so this interior region is 
filled with radiation and particles on closed timelike curves cycling 
around the singularity. The real question of course is whether there is 
some entanglement of states between the regions I and II, two timelike 
regions that may have multiverse considerations, and whether the ambiguity 
of how one pushes a spacelike surface forwards means there are also 
entanglements in the two interior regions.

LC



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Re: Inside Black Holes

[Lawrence Crowell]

On Saturday, January 13, 2018 at 5:56:01 PM UTC-6, John Clark wrote:
>
> On Sat, Jan 13, 2018 at 2:35 PM, Lawrence Crowell <
> goldenfield...@gmail.com > wrote:
>
> ​> ​
>> Go to https://jila.colorado.edu/~ajsh/insidebh/ to look an numerical 
>> simulations of what falling into a black hole would appear as. In effect 
>> nothing spectacularly different appears upon crossing the horizon.
>>
>
> ​I think that would be true if, as in your example, the observer were 
> freely falling into the Black Hole, but 
> if I was hovering just outside the Event Horizon in a super powerful 
> spaceship I could observe the Black Hole evaporating in just a few minutes 
> even though 
> ​to​
>  you
> ​,​
> who is far away 
> ​in a much weaker gravitational field, ​
> that would take many trillions of years; the only problem is
> ​ in addition to the Black Hole evaporation​
> I would also observe many trillions of years worth of Hawking Radiation in 
> just a few minutes, and that would cook me. However if I had no spaceship 
> and was just freely falling through the Event Horizon the Hawking Radiation 
> wouldn't bother me at all
> ​ and I couldn't even tell when I reached the Event Horizon.​
>  
>
> ​A​
> t least that was the idea before 5 or 6 years ago when 
> ​the idea of a Black Hole Firewall came up:
>
> http://www.nature.com/news/astrophysics-fire-in-the-hole-1.12726#b8
>
> Such a firewall violates Einstein's equivalence principle and claims even a
>  
> ​freely ​
> falling 
> ​m​
> an 
> ​will​
>  
> ​will​
>  cooked at the Event Horizon, but I don't understand Black Hole Firewalls 
> worth a damn.
> ​ 
>
>  John K Clark
>

The near horizon condition for an accelerated observer is different. If one 
accelerates in order to remain stationary at some distance d from the 
horizon this requires an acceleration a = c^2/d. The spacetime this 
observer witnesses is AdS_2×S^2, which I work out in this page on Stack 
Exchange 
.
 
This vacuum is negative with no lower bound, which is odd for quantum field 
theory and quantum mechanics with a bounded spectrum, and so quantum field 
are emitted from near the horizon. This accelerated observer in effect 
observes Hawking radiation within a frame that is accelerated in time. As 
the observer is able to accelerate to remain ever closer to the horizon, a 
null congruence with no time, the duration of the black hole is shortened 
ever further. Hence Hawking radiation appears to come gushing out rapidly. 

https://physics.stackexchange.com/questions/262735/ads-black-holes/262744#262744

I wrote a post on a possible way to understand the firewall. This issue 
tells us there is some relationship between quantum mechanics and general 
relativity not canonically understood. The initial quantum state of a black 
hole becomes randomized as Hawking radiation is emitted. Once half the mass 
of the black hole is lost to Hawking radiation the quantum states on the 
black hole have been randomized beyond the ability of a quantum error 
correction code.

In some recent work I was motivated by Maryam Mirzakhani's death. She died 
of breast cancer last July, and the news for various reason made me angry. 
I had read one of her paper's back in 2014 when she won the Fields medal, 
and at the time I thought this had something maybe to do with physics. Last 
spring I studied the Ryu-Takayanagi (RT) formula and for some reason the 
day I heard of Maryam's death the insight on how her work connects with 
this hit me.

There is this problem with how gravitation and quantum mechanics merge or 
function in a single system. It is often said we understand nothing of 
quantum gravity, and this is not quite so. Even with the based canonical 
quantization of gravity from the 1970s in a weak limit is computable and 
tells you something. This theoretical understanding is very limited and big 
open questions remain. Of course since then far more progress has been 
made. The AdS/CFT correspondence, the Raamsdonk equivalence between 
entanglement and spacetime and the RT formula are some of the more recent 
developments. These indicate how spacetime physics has a correspondence or 
maybe equivalency with quantum mechanics or quantum Yang-Mills fields. 
However, an obstruction exists that appears very stubborn.

The vacuum is filled with virtual pairs of fields. With a black hole the 
gravity field causes one of these pairs to fall into the black hole and the 
other to escape. This means the quantum particle or photon that escapes as 
Hawking radiation is entangled with the pair that falls into the black 
hole, and so this means Hawking radiation is entangled with the black hole. 
So at first blush there seems to be no problem. However, if we think of a 
thermal cavity heated to high temperature photons that escape are entangled 
with quantum states of atoms composing the cavity. Once the entanglement 
entropy reaches a maximum at ha

Re: Inside Black Holes

[Brent Meeker]

On 1/13/2018 3:55 PM, John Clark wrote:
​I think that would be true if, as in your example, the observer were 
freely falling into the Black Hole, but
if I was hovering just outside the Event Horizon in a super powerful 
spaceship I could observe the Black Hole evaporating in just a few minutes


That seems doubtful since Hawking radiation has its peak wavelength on 
the order of the diameter of the black hole and originates in the 
vicinity, i.e. within a few radii of the black hole, not "at the event 
horizon".


Brent

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Re: Inside Black Holes

[Brent Meeker]

On 1/13/2018 2:44 PM, agrayson2...@gmail.com wrote:



On Saturday, January 13, 2018 at 2:59:00 PM UTC-7, Brent wrote:

Classically, the radiation isn't "trapped"; it goes to the
singularity (what the QM does? dunno).  The inflowing radiation is
just that starlight that falls on the event horizon...which is not
particularly bright.

Brent


I'm referring to the INTERIOR of the BH.


So am I.

If the radiation is trapped inside, the environment is likely hot and 
bright.


Or it's absorbed by the singularity...or whatever is really there. 
There's not reasonable picture in which it is "trapped inside" and is 
flying around inside the black hole.  Inside a Schawarzschild black hole 
"the singularity" is on the future of every world line, including null 
ones.  Inside a Kerr-Newman black hole it may be possible to miss "the 
singularity" but then it appears to connect to a another spacetime.  
Both of these are solutions for eternal black holes, so when it's a 
black hole that forms and then evaporates the solutions may not hold.  
However, except near "the singularity" the analyses would hold and so 
except for within nanoseconds of "the singularity" all photons are going 
to be traveling toward "the singularity" and not flying around 
willy-nilly, "trapped" in the black hole.  They can't turn around 
because that direction is the past.


Brent




What happens to infalling matter? Converted to radiation? AG


On 1/13/2018 9:18 AM, agrays...@gmail.com  wrote:

Extremely hot and bright due to trapped radiation? AG
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Re: Inside Black Holes

[John Clark]

On Sat, Jan 13, 2018 at 2:35 PM, Lawrence Crowell <
goldenfieldquaterni...@gmail.com> wrote:

​> ​
> Go to https://jila.colorado.edu/~ajsh/insidebh/ to look an numerical
> simulations of what falling into a black hole would appear as. In effect
> nothing spectacularly different appears upon crossing the horizon.
>

​I think that would be true if, as in your example, the observer were
freely falling into the Black Hole, but
if I was hovering just outside the Event Horizon in a super powerful
spaceship I could observe the Black Hole evaporating in just a few minutes
even though
​to​
 you
​,​
who is far away
​in a much weaker gravitational field, ​
that would take many trillions of years; the only problem is
​ in addition to the Black Hole evaporation​
I would also observe many trillions of years worth of Hawking Radiation in
just a few minutes, and that would cook me. However if I had no spaceship
and was just freely falling through the Event Horizon the Hawking Radiation
wouldn't bother me at all
​ and I couldn't even tell when I reached the Event Horizon.​


​A​
t least that was the idea before 5 or 6 years ago when
​the idea of a Black Hole Firewall came up:

http://www.nature.com/news/astrophysics-fire-in-the-hole-1.12726#b8

Such a firewall violates Einstein's equivalence principle and claims even a

​freely ​
falling
​m​
an
​will​

​will​
 cooked at the Event Horizon, but I don't understand Black Hole Firewalls
worth a damn.
​

 John K Clark

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Re: Inside Black Holes

[Stathis Papaioannou]

On Sun, 14 Jan 2018 at 9:44 am,  wrote:

>
>
> On Saturday, January 13, 2018 at 2:59:00 PM UTC-7, Brent wrote:
>>
>> Classically, the radiation isn't "trapped"; it goes to the singularity
>> (what the QM does? dunno).  The inflowing radiation is just that starlight
>> that falls on the event horizon...which is not particularly bright.
>>
>> Brent
>>
>
> I'm referring to the INTERIOR of the BH. If the radiation is trapped
> inside, the environment is likely hot and bright. What happens to infalling
> matter? Converted to radiation? AG
>

The event horizon is usually considered the border between the black hole
and the rest of the universe.

> --
Stathis Papaioannou

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Re: Inside Black Holes

[agrayson2000]

On Saturday, January 13, 2018 at 2:59:00 PM UTC-7, Brent wrote:
>
> Classically, the radiation isn't "trapped"; it goes to the singularity 
> (what the QM does? dunno).  The inflowing radiation is just that starlight 
> that falls on the event horizon...which is not particularly bright.
>
> Brent
>

I'm referring to the INTERIOR of the BH. If the radiation is trapped 
inside, the environment is likely hot and bright. What happens to infalling 
matter? Converted to radiation? AG 

>
> On 1/13/2018 9:18 AM, agrays...@gmail.com  wrote:
>
> Extremely hot and bright due to trapped radiation? AG
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Re: Inside Black Holes

[Brent Meeker]

Classically, the radiation isn't "trapped"; it goes to the singularity 
(what the QM does? dunno).  The inflowing radiation is just that 
starlight that falls on the event horizon...which is not particularly 
bright.


Brent

On 1/13/2018 9:18 AM, agrayson2...@gmail.com wrote:

Extremely hot and bright due to trapped radiation? AG
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Re: Inside Black Holes

[Lawrence Crowell]

Go to https://jila.colorado.edu/~ajsh/insidebh/ to look an numerical 
simulations of what falling into a black hole would appear as. In effect 
nothing spectacularly different appears upon crossing the horizon. In fact 
the event horizon becomes an apparent horizon, which has an identical 
appearance. In fact one can't know exactly, as in a Dedekind cut, when the 
event horizon becomes an apparent horizon. You would need a clock with 
accuracy that could only be had with energy far more than the mass of the 
black hole.

LC

On Saturday, January 13, 2018 at 11:18:16 AM UTC-6, agrays...@gmail.com 
wrote:
>
> Extremely hot and bright due to trapped radiation? AG
>

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Inside Black Holes

[agrayson2000]

Extremely hot and bright due to trapped radiation? AG

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New Type of Star Emerges From Inside Black Holes

[Edgar L. Owen]

FYI only. Don't have an opinion. Edgar


New Type of Star Emerges From Inside Black Holes

Born inside black holes, “Planck stars” could explain one of astrophysics’ 
biggest mysteries and may already have been observed by orbiting gamma ray 
telescopes, say cosmologists

• The Physics arXiv Blog in The Physics arXiv Blog
Black holes have fascinated scientists and the public alike for decades. 
There is special appeal in the idea that the universe contains regions of 
space so dense that light itself cannot escape and so extreme that the laws 
of physics no longer apply. What secrets can these extraordinary objects 
hide?

Today, we get an answer thanks to the work of Carlo Rovelli at the 
University of Toulon in France, and Francesca Vidotto at Radboud University 
in the Netherlands. These guys say that inside every black hole is the 
ghostly, quantum remains of the star from which it formed. And that these 
stars can later emerge as the black hole evaporates.

Rovelli and Vidotto call these objects “Planck stars” and say they could 
solve one of the most important questions in astrophysics. What’s more, 
evidence for the existence of Planck stars may be readily available, simply 
by looking to the heavens.

Black holes arise naturally from Einstein’s theory of general relativity 
which predicts that gravity influences the trajectory of photons moving 
through space. Indeed, when gravity is strong enough, light shouldn’t be 
able to escape at all. That region is then a black hole.

Astrophysicists have long believed that black holes form when stars a 
little bigger than the Sun run out of fuel. No longer supported by thermal 
energy, the star collapses under its own weight to form a black hole. Since 
there is no known force that can stop this collapse, astrophysicists have 
always assumed that it eventually forms a singularity, a region of space 
that is infinitely dense.

But this has never been entirely satisfactory. The laws of physics break 
down in a region of infinite density, leaving physicists scratching their 
heads over what must be going on inside a black hole.

Even worse, many physicists believe black holes slowly evaporate and 
disappear. That raises problems because the information that describes an 
object must fully determine its future and be fully derivable from its 
past, at least in principle. But if black holes disappear, what happens to 
this information?

Nobody knows, a problem known as the “information paradox” and one of the 
hottest mysteries in astrophysics.

Now Rovelli and Vidotto have the answer. They begin by revisiting some 
ideas about what might happen should the universe end in a big crunch, the 
opposite of a big bang. Their key insight is that quantum gravitational 
effects prevent the universe from collapsing to infinite density. Instead, 
the universe ”bounces” when the energy density of matter reaches the Planck 
scale, the smallest possible size in physics.

That’s hugely significant. “The bounce does not happen when the universe is 
of planckian size, as was previously expected; it happens when the matter 
energy density reaches the Planck density,” they say. In other words, 
quantum gravity could become relevant when the volume of the universe is 
some 75 orders of magnitude larger than the Planck volume.

Rovelli and Vidotto say the same reasoning can be applied to a black hole. 
Instead of forming a singularity, the collapse of a star is eventually 
stopped by the same quantum pressure, a force that is similar to the one 
that prevents an electron falling into the nucleus of an atom. “We call a 
star in this phase a “Planck star”,” they say.

Planck stars would be small— stellar-mass black hole would form a Planck 
star about 10^-10 centimetres in diameter. But that’s still some 30 orders 
of magnitude larger than the Planck length.

An interesting question is whether these Planck stars would be stable 
throughout the life of the black hole that surrounds them. Rovelli and 
Vidotto have a fascinating answer. They say that the lifetime of a Planck 
star is extremely short, about the length of time it takes for light to 
travel across it.

But to an outside observer, Planck stars would appear to exist much longer. 
That’s because time slows down near high-density masses. For such an 
observer , a Planck star would last just as long as its parent black hole.

It then becomes possible for the black hole to interact with the Planck 
star it contains. Rovelli and Vidotto point out that as the black hole 
evaporates and shrinks, its boundary will eventually meet that of the 
Planck star as it expands after the bounce. “At this point there is no 
horizon any more and all information trapped inside can escape,” they say.

That immediately solves the information paradox. The information isn’t lost 
or trapped inside an unimaginably small region of space but eventually 
re-emitted into the universe.

There’s yet another exciting consequence of these ideas. Rovell