Light (not) escaping from black holes

[Outhouse]

As far as gravity and our lack of knowledge, Neil Degrasse Tyson says it well. "" “we can describe gravity, we can say what it does to other things, we can measure it, we can work with it. But when you start asking what it is, or how it works, I do not know”.""

 

[alantheastronomer]

Neutron degeneracy pressure doesn't refer to a single neutron, it's the pressure between neutrons within a neutron star. As far as neutrons becoming compressed into a singularity as a black hole is formed, we really don't know because our knowledge about what happens inside the event horizon breaks down.

 

[mfb]

As far as gravity and our lack of knowledge, Neil Degrasse Tyson says it well. "" “we can describe gravity, we can say what it does to other things, we can measure it, we can work with it. But when you start asking what it is, or how it works, I do not know”.""

These questions become philosophy. Physics has an accurate description of the phenomenon - that is the best you can hope for. Fundamental "why" questions are philosophy, they are impossible to answer (although some philosophers think otherwise).

 

[Outhouse]

Yeah, none of that is correct.

So just for my

These questions become philosophy. Physics has an accurate description of the phenomenon - that is the best you can hope for. Fundamental "why" questions are philosophy, they are impossible to answer (although some philosophers think otherwise).

This started when I stated we do not really have a working hypothesis as to the mechanics behind it. Its not philosophical IMHO when asking what it is, and how it works. My point, we measure its effects but cannot explain what causes the weak force other than general relativity which is incomplete to the actual nature of gravity.

 

[Outhouse]

Neutron degeneracy pressure doesn't refer to a single neutron, it's the pressure between neutrons within a neutron star. As far as neutrons becoming compressed into a singularity as a black hole is formed, we really don't know because our knowledge about what happens inside the event horizon breaks down.

Thank you very much, that was key for my understanding.

 

[Dale]

There is a hypothesis for "this thing" that happens? the actual mechanics behind the weak force?

Yes, the Standard model explains the mechanics of the strong force, the weak force, and the electromagnetic force. Similarly general relativity explains the mechanics of gravity.

This started when I stated we do not really have a working hypothesis as to the mechanics behind it.

We do: General relativity and the Standard Model

 

[mfb]

The weak force or weak interaction is an independent interaction that has nothing to do with gravity, be careful with that expression unless you actually mean the weak interaction.

This started when I stated we do not really have a working hypothesis as to the mechanics behind it. Its not philosophical IMHO when asking what it is, and how it works.

Physics can give you tools to predict experimental results. That is all physics can do. Everything beyond that is philosophy.

 

[russ_watters]

This started when I stated we do not really have a working hypothesis as to the mechanics behind it. Its not philosophical IMHO when asking what it is, and how it works. My point, we measure its effects but cannot explain what causes the weak force other than general relativity which is incomplete to the actual nature of gravity.

Any question about "how something works" can lead to an endless - and pointless - string of "why" or "how" questions. The reality is that all that really matters is what we can see (observe) - and what is observed is very well described/explained. What we can't observe may not even exist, so it doesn't need an explanation. Talk of "the nature of..." beyond what we observe doesn't lead to any real understanding.

 

[Outhouse]

Talk of "the nature of..." beyond what we observe doesn't lead to any real understanding.

I think it is a lot easier to say we don't know the first thing about what forms and creates gravity beyond general relativity and the Standard Model, which are incomplete.

We can only measure it we can only partially explain it, in its relationship to bent space/time.

 

[Outhouse]

The combination of these two factors--pressure gravitates, and neutrons become relativistic as degeneracy pressure rises--combine to determine a maximum mass for neutron stars, above which no amount of pressure can hold the star up against its own gravity, and it collapses to a black hole

So it safe to say when the star is over 3 solar masses the gravity overcomes the degeneracy pressure and the neutrons are popped not compressed?

 

[PeterDonis]

I think it is a lot easier to say we don't know the first thing about what forms and creates gravity beyond general relativity and the Standard Model, which are incomplete.

Only if you know that the concept of "what forms and creates gravity", over and above what we can model using GR, makes sense to begin with. What if it doesn't? That concept comes from the human mind, not nature.

So it safe to say when the star is over 3 solar masses the gravity overcomes the degeneracy pressure

Yes. I believe the current upper limit on the maximum mass for a neutron star is about 2.7 solar masses (we don't know the exact maximum mass, but we know what range it is in), so 3 solar masses is over the limit.

the neutrons are popped not compressed?

I have no idea what you mean by this. If an object made of neutrons collapses to a black hole, the neutrons end up inside the hole.

 

[Outhouse]

If an object made of neutrons collapses to a black hole, the neutrons end up inside the hole.

I see the neutrons being changed/popped, much the same way the hadron collider destroys atomic particles.

Only if you know that the concept of "what forms and creates gravity",

Why can't we use the term a relational theory in regards to general relativity? we observe and report back the mathematical relationship without knowing why the bending of space causes the weak force.

And maybe it was you who mentioned the quantum level here, is what is left to be explained, and I am looking at the exact reasons the two are not cohesive. The actual mechanics causing the force not described by GR

 

[PeterDonis]

I see the neutrons being changed/popped, much the same way the hadron collider destroys atomic particles.

Sorry, I still don't know what this means. The LHC does not "destroy" particles; it just induces high-energy interactions that won't happen under normal conditions here on Earth. Some of those interactions involve particles being converted into other particles.

It's certainly possible that, once a collapsing object like a former neutron star has collapsed to a black hole, and the collapsing matter inside the hole reaches high enough temperature, that interactions similar to what is observed inside the LHC might happen; but that would be well after the collapse has formed an event horizon around itself and is not observable from outside. The LHC interactions have nothing to do with what is inside an ordinary neutron star, or even one that has accreted some matter and is now over the maximum mass limit and is collapsing to a black hole, but has not yet formed a horizon.

Why can't we use the term a relational theory in regards to general relativity? we observe and report back the mathematical relationship without knowing why the bending of space causes the weak force.

The bending of spacetime does not "cause" gravity (and gravity is not the same as the weak interaction; that's a separate interaction, which is involved in processes like nuclear beta decay). The bending of spacetime is gravity. They're just different names for the same thing.

Asking why spacetime bends in the presence of matter and energy is like asking why the laws of physics are what they are. There's no way to resolve such a question experimentally, so it's off topic here.

im looking at the exact reasons the two are not cohesive

Meaning quantum mechanics and GR? It's because nobody knows how a quantum theory can coexist with a non-quantum theory. The only thing we understand is how to figure out the classical limit of a quantum theory; but we don't know any quantum theory of which GR is the classical limit. (The search for a theory of quantum gravity is the search for such a quantum theory, but so far it has not come up with one that has been confirmed to work.)

The actual mechanics causing the force not described by GR

In GR gravity is not a force at all; it's spacetime curvature.

 

[russ_watters]

I think it is a lot easier to say we don't know the first thing about what forms and creates gravity beyond general relativity and the Standard Model, which are incomplete.

We can only measure it we can only partially explain it, in its relationship to bent space/time.

Again, "partially explain" means there are observations it doesn't explain. What are those observations? If you can't think of any specifics, then you can't say, scientifically, that it is incomplete.

If the claim is based on vague how/why questions, then they are outside the scope of science.

 

[Outhouse]

The LHC interactions have nothing to do with what is inside an ordinary neutron star

Yes agreed.

The LHC does not "destroy" particles

Not a scientific word true, but protons are brought to a state of byproducts by collision and then studied as they decay.

There's no way to resolve such a question experimentally

We cannot test infinite experiments, but cannot we use Perturbation methods to help us form plausibility of a workable reconciliatory hypothesis?

 

[Outhouse]

If the claim is based on vague how/why questions, then they are outside the scope of science.

We don't have meaningful physical predictions of quantum field theory and gravity bosons, correct?

[WIKI] A bigger challenge is to find a way to quantize the gravitational field, resulting in a theory of quantum gravity (QG) which would unite gravity in a common theoretical framework with the other three forces.

 

[russ_watters]

We don't have meaningful physical predictions of quantum field theory and gravity bosons, correct?

[WIKI] A bigger challenge is to find a way to quantize the gravitational field, resulting in a theory of quantum gravity (QG) which would unite gravity in a common theoretical framework with the other three forces.

Parts of that are still a work in progress, but there are lots of "meaningful predictions" that work. And here's what you said before:

...we don't know the first thing about what forms and creates gravity beyond general relativity and the Standard Model, which are incomplete.

The statement has more twists than a pretzel. "Don't know the first thing" except what we know (GR and the standard model), which is a lot. The way you write it implies we know 1% when in reality we know 99%.

 

[PeterDonis]

cannot we use Perturbation methods to help us form plausibility of a workable reconciliatory hypothesis?

No. This has been tried; in the 1960s a number of physicists, including Feynman, worked on constructing a quantum field theory of a massless spin-2 field, which theoretical considerations said should be the graviton, the quantum of gravity. They found out that, when a perturbative theory of such a field was constructed, correct to all orders, its field equation was simply the Einstein Field Equation of GR. The problem was, this theory was not renormalizable, so all the field equation really tells you is the low energy limit; it doesn't tell you anything about quantum gravity at higher energies, which is what we need to know.

We don't have meaningful physical predictions of quantum field theory and gravity bosons, correct?

If by "gravity bosons" you mean the massless, spin-2 graviton, GR is the "meaningful physical prediction" of such a QFT at low energies (see above). The problem is that "low energies" here means "energies small compared to the Planck energy", and the Planck energy is about 20 orders of magnitude larger than the largest energy we can probe with our experiments (the LHC energy). So basically what our current knowledge of quantum gravity tells us is that whatever the quantum nature of gravity is, it's completely negligible as far as experimental predictions at any energy less than about 20 orders of magnitude larger than the largest energy we can currently probe experimentally. Which isn't very useful, but there it is.

 

[PeterDonis]

a theory of quantum gravity (QG) which would unite gravity in a common theoretical framework with the other three forces.

While this is what most physicists probably expect, it's worth keeping in mind that we don't know that this is how things will come out. Some physicists (Freeman Dyson is one notable one among them) have expressed the opinion that we might end up finding out that gravity is not like the other interactions and can't be unified with them. Not as a theory to be tested, but as a possibility not to be ruled out at this very rudimentary stage of our knowledge.

 

[bhobba]

Asking why spacetime bends in the presence of matter and energy is like asking why the laws of physics are what they are. There's no way to resolve such a question experimentally, so it's off topic here.

That's exactly it.

There are certain laws we are pretty sure of such as the formalism of Lagrangian Field Theory. You combine that with considering space-time in generalized coordinates and mathematically describing it by what's called a pseudo-Riemannian geometry (fancy name for curved space time) pretty much leads to GR. Why are all those things true? Well I can explain them, and even derive some of them from more fundamental laws such as the symmetry of an inertial frame, and even make it sound very reasonable to the point you say - yes I see why nature is like that - but really at a fundamental level what have you done.

For example the following makes SR (flat space-time) seem almost inevitable:
http://www2.physics.umd.edu/~yakovenk/teaching/Lorentz.pdf

After reading that you may say - I know why SR is true - and in a certain sense you do - but in another sense you do not - you are faced with the question - why do inertial frames exist with those symetry properties?

You merely replace some assumptions with others. Natures laws are as natures laws are - we just describe them - although they can be described in a clear and illuminating way (like the above paper), which is something I love to do, it must always be borne in mind that's all we are doing is describing natures laws. Nature determines them - not us.

Thanks
Bill

 

[Outhouse]

Natures laws are as natures laws are - we just describe them

I would much rather have question I cannot answer, then answers I cannot question.

 

[Outhouse]

The statement has more twists than a pretzel. "Don't know the first thing" except what we know (GR and the standard model), which is a lot. .

Again we only observe gravity, we do not understand where the force even comes from. Yes we understand the effect of gravity in great detail, we just cannot recreate the force in any equation what so ever. No one knows how to make gravity.

 

[Outhouse]

I see BH as popped neutrons and other atomic elements broken down. When Gravity is strong enough to break down degeneracy pressure a BH is formed. And it seems we have that weight pretty closely figured out. I guess we start getting into the whole matter in matter out equation, I would guess if a BH exploded the cooled particles would form atoms again from the debris much the same way we see in the BB.

 

[PeterDonis]

I see BH as popped neutrons and other atomic elements broken down.

A black hole is vacuum; it's not "made" of anything except spacetime curvature. There may be objects inside it that have fallen in, but unless and until they are close enough to the singularity for tidal gravity to tear them apart, they're no different from objects anywhere else.

I would guess if a BH exploded the cooled particles would form atoms again from the debris much the same way we see in the BB

A BH can't explode. The time reverse of a BH, a white hole, is not the same spacetime geometry as the Big Bang.

At this point this thread is simply your personal speculations, and is therefore closed. The substantive questions you have asked have been answered.