Is the Pressure Inside a Black Hole So Intense That Atoms Cannot Hold Form?

[Karlox]

Greetings, I've been thinking about the escape velocity having to be greater than c inside the event horizon for a particle to escape.
Since this cannot happen, I picture the matter at the core as an insanely dense ball of atoms. But, could the pressure be so intense that atoms cannot hold such form, and the particles that compose them are ripped apart, leaving only an infinitely dense "ball of energy"?

Has any research been done on how well this resembles the primordial states of our universe? From within the EH, it would also look 'infinte in space'.

I know this is highly speculative,(apologies) thus the title, but to rule out this possibility, I wonder if any estimation has been done about the pressure atoms face in the black hole's core, and how this may disrupt particles.

 

[Orodruin]

Greetings, I've been thinking about the escape velocity having to be greater than c inside the event horizon for a particle to escape.

This is ungortunately a grossly overpopularised version of what is going on near a black hole.

I picture the matter at the core as an insanely dense ball of atoms.

This is most likely not a very good heuristic of what is going on. The singularity in Schwarzschild spacetime is more like a moment in time than it is a position in space.

 

[kimbyd]

Greetings, I've been thinking about the escape velocity having to be greater than c inside the event horizon for a particle to escape.
Since this cannot happen, I picture the matter at the core as an insanely dense ball of atoms. But, could the pressure be so intense that atoms cannot hold such form, and the particles that compose them are ripped apart, leaving only an infinitely dense "ball of energy"?

Atoms can't exist long before you get to the center of a black hole. Neutron stars have too much pressure for atoms to exist.

As to your question, the problem is that we have no theory which can accurately describe the center of a black hole. General Relativity basically just tells us that at some point close to the center, the theory can no longer describe what's going on (even in principle): attempting to do so results in mathematical contradictions. Describing what happens in the interior of a black hole definitely requires us to know the correct theory of quantum gravity, which we don't yet know. And given that direct experimentation of the interior of the black hole is likely impossible, we may never know what happens inside a black hole even if we can determine the correct theory of quantum gravity.

 

[Grinkle]

@kimbyd Can one take a "big bang" approach at description and meaningfully discuss what happens after a particle crosses the EH to some point prior to it reaching the singularity?

 

[kimbyd]

@kimbyd Can one take a "big bang" approach at description and meaningfully discuss what happens after a particle crosses the EH to some point prior to it reaching the singularity?

No. The Big Bang theory offers no insight whatsoever into resolving a singularity, as it doesn't describe a singularity. Similar to the black hole case, the singularity cannot be a part of the theory, or it breaks down.

 

[JMz]

I believe @Grinkle is asking about the trip, not the destination: what the particle or observer experiences before getting too close and being "spaghettified".

The answer is, Yes, GR does give an answer... though whether it's correct or not is necessarily an open question. The short answer is, If it were you, and the BH were very large, you would gradually feel the tidal pull increase as you approached, and that feeling would merely strengthen smoothly as you crossed the EH... until you turned into spaghetti at some point. (You get stretched in the radial direction but crushed in the other two dimensions. Hence the spaghetti.)

If the hole were large enough for you to experience this over a few seconds or longer, you would not feel anything change abruptly as you crossed the EH, though you would be irrecoverably doomed at that point. For the largest known BHs, you could -- if I recall correctly -- exist for at least many hours, though whether your body could continue to function that long, I do not know. (Any students out there who would like to calculate how close you can get before the tides of a 10^10-solar mass BH stretch & squeeze neural tissue too strongly to function? Is this inside the EH?)

 

[Ibix]

Any students out there who would like to calculate how close you can get before the tides of a 10^10-solar mass BH stretch & squeeze neural tissue too strongly to function? Is this inside the EH?

Wheeler did something of the sort - the "ouch radius".

 

[JMz]

Wheeler did something of the sort - the "ouch radius".

Why am I not surprised? :-)

 

[Grinkle]

asking about the trip, not the destination:

Yes - this is what I am wondering.

The Big Bang theory offers no insight whatsoever into resolving a singularity

I know. I meant that we discuss the early universe as far back as we have theory to describe, we don't just say at time zero we have no model so we can't say anything about the entire history of the universe.

I was suggesting that as an analogy and asking if an inability to model whatever is at the singularity means we have no theory to describe any part of what is behind an EH. Experiment to verify is not possible, I get that. If comparing the descriptive process to how we discuss the early universe is not applicable, I retract that.

Asking differently -

If one is in a physics laboratory that is free-falling into an enormous black hole, are there any experiments one can be doing to determine when one has crossed the EH? I think one can know by calculating the size of the BH and keeping track of ones position, but that is not what I mean. Is there any kind of experiment that can act as an EH detector, according to GR?

 

[Orodruin]

I believe you are asking if there is any local measurement that can be made to know if you have crossed an event horizon or no. The answer to that is "no". This is due to an event horizon being a global property of the space-time and not a local property.

 

[Grinkle]

The answer to that is "no".

Then perhaps the answer to the OP's question is that the pressure is exactly the same just inside the EH as just outside the EH if one is free falling into the EH?

 

[russ_watters]

Then perhaps the answer to the OP's question is that the pressure is exactly the same just inside the EH as just outside the EH if one is free falling into the EH?

I would go further to say that the word "pressure" doesn't apply here. I'm on the surface of the Earth; what's my "pressure"? Pressure of what?

 

[Orodruin]

To me, the OPs question is based on the common but faulty assumption that there is some sort of celestial body left inside the black hole, which disregards what the geometry of the space-time inside the event horizon actually looks like. The reason, I suppose, is that the typical mental image of space and time that a layman creates in their minds no longer applies.

 

[PAllen]

One thing you can say about pressure is that as a spherical mass collapses, central pressure approaches infinite before the Schwarzschild radius is reached. This is a consequence of Buchdahl’s theorem and related results relaxing its assumptions. For example,

https://arxiv.org/abs/gr-qc/0605097

 

[timmdeeg]

If one is in a physics laboratory that is free-falling into an enormous black hole, are there any experiments one can be doing to determine when one has crossed the EH? I think one can know by calculating the size of the BH and keeping track of ones position, but that is not what I mean. Is there any kind of experiment that can act as an EH detector, according to GR?

My suggestion is to measure the redshift of radially infalling light of a faraway source, whereby $z=\sqrt{r_s/r}$, with $r$ the r-coordinate of the lab. Hence while crossing the event horizon they measure $z=1$.

 

[PeterDonis]

as a spherical mass collapses, central pressure approaches infinite before the Schwarzschild radius is reached

If this statement were correct as you state it, no object could ever collapse to a black hole, because the unbounded central pressure would push back and prevent that.

Actually, Buchdahl's Theorem does not apply in the case under discussion because it assumes a static spacetime, and the spacetime describing a collapsing mass is not static. So pressure inside a collapsing object can remain finite as it forms a black hole. Heuristically, this is because the pressure is less than what would be required to prevent the collapse, whereas Buchdahl's Theorem assumes that the pressure is sufficient to hold the body in static equilibrium.

 

[Ibix]

You can't spot the event horizon from a small laboratory because spacetime is locally flat. But you could do it from a not-quite-so-small laboratory, I think. You could measure the local curvature from tidal effects, and hence get some combination of the mass and your r coordinate such as the Kretschmann scalar. I'm not sure if you can extract the r coordinate without knowing the mass in advance.

 

[PeterDonis]

I'm not sure if you can extract the r coordinate without knowing the mass in advance.

Since the $r$ coordinate is defined as the "areal radius", you would need to be able to measure the area of the 2-sphere on which your current position lies. There are possible ways to do that, but I don't think any of them qualify as local measurements.

 

[JMz]

However, if you knew the mass (you watched small bodies orbit the BH before you took the plunge), you could presumably determine a radial coordinate locally by measuring the tidal difference across your lab (or across your body, in Wheeler's example).

 

[PeterDonis]

if you knew the mass (you watched small bodies orbit the BH before you took the plunge), you could presumably determine a radial coordinate locally by measuring the tidal difference across your lab (or across your body, in Wheeler's example).

Yes, agreed.

 

[MajinMatt]

Greetings, I've been thinking about the escape velocity having to be greater than c inside the event horizon for a particle to escape.
Since this cannot happen, I picture the matter at the core as an insanely dense ball of atoms.

And why exactly can't a particle have an escape velocity greater than c?

 

[Ibix]

And why exactly can't a particle have an escape velocity greater than c?

Because it doesn't make sense to talk about an escape velocity from something that can't be escaped. In fact, the reasoning underlying the notion of "escape velocity" breaks down at the event horizon, which is where a naive reading of escape velocity formulae suggests it should reach $c$.

Edit: although I suspect that the OP's reasoning was simply that "you can't travel faster than light", which is also a reasonable point. I.e., arguing that a particle can't have a velocity greater than $c$, not saying that an escape velocity could not be greater than $c$ (although the latter is also true, as discussed in the previous paragraph).