Where do things go after they were sucked by a Blackhole?

[nitsuj]

I'm not reading it that way.

fair enough.

Here is the strongest support I see for Hawking Radiation...maybe more accurately some form of it.

from the wiki page on Hawking Radiation: "Hawking radiation is required by the Unruh effect and the equivalence principle applied to black hole horizons."

...but apparently may lead to other conflicts that need to be theorized away.

 

[gennarakis]

I'm not a black holes expert. Though, what I was trying to say is that you can't describe something you don't know anything about. Matter inside a black hole probably collapses or becomes into another form. No one will ever know until something is observed. Models help you look at he right direction. You can't predict how the laws of physics behave in a whole new phenomena. We expect them to be the same but they might not. And that's what drives scientists' curiosity to find things out. Beautiful models and assumptions in that case don't differ much from sci-fi stories, dealing with the unknown. What we can directly observe is their radius/mass charge and angular momentum. Hawking radiation is part of a model (and trying to be verified at this time in experiments).

 

[stevebd1]

Is the distinction between "rest mass" and energy with respect to gravity relevant for a black hole? When I read a black hole is 20 million time more massive than our sun, does that exclude kinetic energy, pressure ect? I'd guess that value is derived from the observed gravitational effect of the black hole. I can't imagine the calculation includes an estimate of the radiation absorbed because "Oh that's just momentum, not mass. We want to know how massive it is."

What's more, I'm sure if I read about hawking radiation...it will be about radiation...not ejection of matter (rest mass) from the within the black hole. And again it just seems pointless making a mass/energy distinction in this context of changes in gravity of a black hole...why not just call all of it energy?

A more accurate statement might be '..the only way for a black hole to lose irreducible mass is via Hawking radiation, in accordance with https://www.physicsforums.com/threads/black-hole-thermodynamics.762982/'.

 

[at94official]

We cannot know for sure, but presumably it is crushed into the singularity. Some do not think an actual singularity can exist, based on quantum mechanics, so the center of the black whole is the smallest meaningful volume, the Planck volume. Either way, the spacecraft is crunched out of existence.

Yes, I understand that the spacecraft will be crunched , let's say it will disintegrate into its smallest parts ( Into atoms perhaps? ) But my questions means where do they go? If they were sucked in, it would be impossible for it to go back to event horizon right?

 

[nitsuj]

Yes, I understand that the spacecraft will be crunched , let's say it will disintegrate into its smallest parts ( Into atoms perhaps? ) But my questions means where do they go? If they were sucked in, it would be impossible for it to go back to event horizon right?

A neutron star "crushes" things, beyond atomic structure. Who knows what a black hole does... but "crushed" may not be the right word as it implies things like a surface to "land" on.

The things go "elsewhere".

 

[Drakkith]

The things go "elsewhere".

What do you mean? As far as I understand, matter does not go anywhere. It stays in the black hole, probably in an unknown form or state due to the extreme pressure.

 

[nitsuj]

What do you mean? As far as I understand, matter does not go anywhere. It stays in the black hole, probably in an unknown form or state due to the extreme pressure.

In the same sense of the "elsewhere" region of a light cone...simply a cheeky comment referring to the physical elusiveness...or physical insignificance to an observer (distant)

 

[Sun E Man]

It's too bad that black holes got named as such. They are not holes at all, but the most condensed masses we know about as far from being a hole as anything can get. (That we know of so far.) Food for thought. If two of these masses got close enough to each other their gravitational pull would bring them together at some speed faster than light. That would be a collision of such magnitude that you would think that they would break up and send debris and energy in many different directions. That would be a small bang comparable to "The Big Bang". Or would they just combine and have a new gravitational pull of x + y? It is said that nothing can go faster than light. This is an untrue statement because light goes faster than it's own speed when it enters a (I don't like to use the term) black hole. Think about it.

 

[phinds]

It's too bad that black holes got named as such. They are not holes at all, but the most condensed masses we know about as far from being a hole as anything can get. (That we know of so far.) Food for thought.

Well, "hole" is not all THAT bad a description, since they take stuff out of normal spacetime like putting it into a deep hole

If two of these masses got close enough to each other their gravitational pull would bring them together at some speed faster than light.

Nonsense. Where did you ever get that idea?

That would be a collision of such magnitude that you would think that they would break up and send debris and energy in many different directions. That would be a small bang comparable to "The Big Bang". Or would they just combine and have a new gravitational pull of x + y?

No, they would just merge. Possible there would be debris from one or both accretion disks but nothing from the BH's themselves.

It is said that nothing can go faster than light.

true that it is said and true that it is true.

This is an untrue statement because light goes faster than it's own speed when it enters a (I don't like to use the term) black hole. Think about it.

No, I think perhaps YOU should think about it. Perhaps you are getting confused because of gravitational time dilation but I don't see how even that could lead you to the conclusion that anything travels faster than light.

 

[ShayanJ]

People here said that the Penrose process can't decrease the mass of the BH. I don't want to argue but here is a quote from page 269 of Sean Carroll's SpaceTime and geometry:

We will now use these ideas to verify that, although you can use the Penrose process to extract energy from the black hole (thereby decreasing M), you cannot violate the area theorem:The area of the event horizon is nondecreasing.

 

[Drakkith]

This is an untrue statement because light goes faster than it's own speed when it enters a (I don't like to use the term) black hole. Think about it.

Light falling into a gravity well does not increase in speed, it increases in frequency.

 

[nitsuj]

People here said that the Penrose process can't decrease the mass of the BH. I don't want to argue but here is a quote from page 269 of Sean Carroll's SpaceTime and geometry:

Post 38 by SteveBD used the correct term, "irreducible mass". The Physics Forum faq has an entry on it. Only Chronos said the Penrose Process doesn't reduce mass, and Drak excluded it saying only Hawking Radiation reduces a BH's mass.

 

[Chronos]

Can anyone cite a rerference claiming the Penrose procees decreases the mass of a black hole.

 

[ShayanJ]

Can anyone cite a rerference claiming the Penrose procees decreases the mass of a black hole.

Carroll(like some other sources) defines an irreducible mass by $M_{irr}^2= \frac 1 2 (M^2+\sqrt{M^4-(\frac J G)^2})$ ans says that it can not decrease, hence the name. But he doesn't state clearly whether M can decrease or not. But he says after you extract all the rotational energy of the BH, you'll have a Schwarzschild BH with mass $M_{irr}$.
But section 13.9 of Lasenby's and Hobson's states it clearly and a bit mathematically.(But it doesn't define an irreducible mass).
Also Zee states it clearly in page 471 of his GR book.
Padmanabhan says that too but you can't see it clearly in his calculations.
It seems to me they aren't making it clear which one, $M \ or \ M_{irr}$, they are considering as the mass of the BH!

 

[Akhand]

I'm just wondering if a spacecraft or any kind of matter was swallowed by a black hole , where does the debris go? I know that it will disintegrate, but even the gravity in there is very strong will there be debris left? If there is, Will it go to other dimension or what?

Thanks,
Austin

there is a theory that they come out of a white hole.
but there is a very high gravity inside as F of gravity
F=GMm/r*r
here M is very much large

 

[ShayanJ]

there is a theory that they come out of a white hole.

No there isn't. Black holes that form from collapsing matter, can't have a white hole.

 

[Akhand]

No there isn't. Black holes that form from collapsing matter, can't have a white hole.

Black holes are formed due the reason that they are acting as a hole in the universe and every hole has it's end that is white hole.

 

[ShayanJ]

Black holes are formed due the reason that they are acting as a hole in the universe and every hole has it's end that is white hole.

White holes arise when people maximally expand the manifold with the Schwarzschild metric. Then you see extra regions which one of those regions is called a white hole because of its properties. But the point is, in the case of a black hole formed from collapsing matter, that part of the manifold which we called white hole, doesn't correspond to any point of the spacetime any more because it resides in the part of spacetime containing star's materials which means we should use a different metric there.

 

[nitsuj]

Can anyone cite a rerference claiming the Penrose procees decreases the mass of a black hole.

I don't have a paper to reference, but the wiki, probably does. It said "A consequence of these laws is that if the process is performed repeatedly, the black hole can eventually lose all of its angular momentum, becoming non-rotating, i.e. a Schwarzschild black hole. In this case the theoretical maximum energy that can be extracted from a black hole is 29% its original mass [4]. Larger efficiencies are possible for charged rotating black holes.[5]"

Here is a paper for the charged BH, Link

 

[Sun E Man]

The speed of gravity is faster than the speed of light or it is a constant force that seems like it is faster than the speed of light. Einstein hypothetically did an experiment in which if the Sun were to loose it's gravity in an instant, the planets would instantly swing out of there orbits. The Earth would already be out of it's orbit for 8.3 minutes + by the time the the sun light reached it that started when the sun lost it's gravity. With this thought in mind is what made me think that the two Black Holes whose gravitational pull is is faster than the speed of light would combine accelerating them to something more than the speed of light. There would be nothing to slow them down as they would have already pulled any thing that was in there way on to them selves now just pulling on each other. I believe this would be especially true once that they came close enough so that their event horizons combined. phinds thank you for your reply and please reply again.

 

[phinds]

The speed of gravity is faster than the speed of light or it is a constant force that seems like it is faster than the speed of light.

No, it is not. Why do you think it is?

Einstein hypothetically did an experiment in which if the Sun were to loose it's gravity in an instant, the planets would instantly swing out of there orbits. The Earth would already be out of it's orbit for 8.3 minutes + by the time the the sun light reached it that started when the sun lost it's gravity.

Can't understand your grammar. If the sun magically vanished, the Earth would continue on in its orbit for 8 more minutes and then start going in a straight line in whatever direction in was moving when the gravity stopped. Light and CHANGES in gravity, which both travel at the speed of light, take 8 minutes to get here from the sun

With this thought in mind is what made me think that the two Black Holes whose gravitational pull is is faster than the speed of light

But it is NOT

would combine accelerating them to something more than the speed of light. There would be nothing to slow them down as they would have already pulled any thing that was in there way on to them selves now just pulling on each other. I believe this would be especially true once that they came close enough so that their event horizons combined. phinds thank you for your reply and please reply again.

 

[Chronos]

All observational evidence to date suggests the 'speed of gravity' is c. Please city any credible examples to the contrary.

 

[EinsteinKreuz]

All observational evidence to date suggests the 'speed of gravity' is c. Please city any credible examples to the contrary.

What is the observational evidence for the speed of gravity being equal to the speed of light in a vacuum?

Particularly given the fact that gravitational radiation has not yet been detected.

 

[Ron Hessinger]

Is it possible for a 'Black Hole' to reach a critical mass- such as in an exploding star?

Yes, it is called the "Big Bang"

 

[phinds]

Yes, it is called the "Big Bang"

This is nonsense. Was it meant as a joke?

 

[phion]

They obviously turn into spaghetti.

 

[Drakkith]

Thread locked, pending moderation.

 

[Drakkith]

The original question has been answered and this thread is starting to fall apart, so I'm locking it. Anyone with related questions can start a new thread. Thread locked.