There are things that can escape from a black hole

[Hypercube]

It occured to me that the common view that nothing can escape from beyond a black hole's event horizon is actually not entirely true, or at least is not necessarily true. The first thing that can obviously escape from a black hole (assuming they exist) are gravitons, I don't think an explanation is needed for that one. The second thing that would have no problem escaping from a black hole (again, assuming they exist) is negative matter, since negative matter is repelled by gravity, it would actually be impossible for it to even reach the event horizon of a black hole; is it just me or would what we think of as a black hole seem indistinguishable from a white hole to anything with a negative mass? And vice-versa.

[Klaynos]

Do you have any references for negative matter, or matter with a negative mass.

 

As I understand it you can't have repulsive gravity because the gauge boson of gravity is a spin 2 particle....

[Hypercube]

That's why I said; "assuming it exists"

[Graviphoton]

Well, there are number of ways a thing can escape a black hole.

One of them be can allow a photon to move at superlumnal speeds, for a short amount of time, according to the uncertainty principle.

Another way, is where you started your journey. If you start your journey from inside the black hole, then you can leave the horizon, because there is a rule which states you cannot pass the same boundary twice. So if you started your journey from inside the black hole, you can leave without any worries.

And ofcourse, normal tachyons, if they do exist, move fast enough so that the gravitational forces do not influence it on its path. They contain a negative mass, the stuff which you are talking about.

 

And there is such a thing as negative mass. Each time the Casimir Effect is in operation within the vacuum, there is a very small amount of negative mass as the result.

[iNow]

How are you using the uncertainty principle to suggest that photons can travel at superluminal speeds? This is an interpretation I've never heard. Can you expand on that?

[Graviphoton]

Sure, buy the book

 

Black Holes and Baby Universes among other essays, By Stephen Hawking.

 

and i qoute

 

''We can allow a photon to move faster-than-light for a very short period of time using the uncertainty principle.''

[iNow]

Okay, pretend I don't have the book. How is it that they supported this idea? Just saying that Stephen Hawking said it does not make it true by default.

[Graviphoton]

They can support almost anything which is scientifically possible. Most of the theories we have concerning cosmology, use events we cannot see directly, morsed in imaginary time frames.

[iNow]

They can support almost anything which is scientifically possible. Most of the theories we have concerning cosmology, use events we cannot see directly, morsed in imaginary time frames.

 

Well, that doesn't address my question now, does it? I'll take this to mean that you are not able to expand on your comment that we can use the uncertainty principle to allow photons to travel superluminally.

[ydoaPs]

So, [math]{\Delta}E{\Delta}t{\geq}\frac{\hbar}{2}[/math] which means for a small enough period of time, there is a huge uncertainty in energy. How do we get from there to ftl?

[Graviphoton]

Don't know. My name isn't Hawking.

 

Sorry, that was cheaky. I mean, i haven't covered yet how to mathematically do this. But if Hawking says he can, he can. I am not going to argue with him.

 

INow

 

I did expand, to give you a reading source. If you mean, (Can I Expand This Mathematically Myself To Show You), the answer is no. Obviously.

[ydoaPs]

You do know that Appeal to Authority is a logical fallacy, right?

[Graviphoton]

No.

 

Suffice to say, i have not appealed to any authorative. I have simply qouted them. How is this such a bad thing? Are we sudden'y not allowed to qoute famous physicists?

[D H]

It occured to me that the common view that nothing can escape from beyond a black hole's event horizon is actually not entirely true, or at least is not necessarily true. The first thing that can obviously escape from a black hole (assuming they exist) are gravitons, I don't think an explanation is needed for that one.

Actually, an explanation is needed. A black hole obviously interacts gravitostatically with a mass outside of the event horizon. How does this occur? There are other interactions that escape a black hole. A black hole can be charged. A charged black hole will interact electrostatically with charged particles outside the event horizon. The gravitostatic and electrostatic interactions have something in common: They are mediated by virtual particles. Virtual photons mediate electrostatic interactions and (hypothetical) virtual gravitons mediate gravitostatic interactions.

 

It is these virtual particles that escape from black holes. Virtual particles in a sense violate the laws of physics. Non-virtual particles do not violate the laws of physics and cannot escape from a black hole. This includes the carriers of gravity waves, non-virtual gravitons. Black holes do not emit gravity waves.

[Graviphoton]

DH is 100% correct. I would just be carefull about the last part. Black Holes can give off gravitational waves in the special circumstance of two black hole collisions.

[Cap'n Refsmmat]

You do know that Appeal to Authority is a logical fallacy, right?

 

Only when said authority figure is an authority on the wrong subject.

[Graviphoton]

Cool. Thanks for that clear-up.

[Sayonara]

The thing is Grav, Hawking fudges for the sake of argument. He does it quite a lot in his coffee table books because there is not likely to be an academic backlash from those merely for the sake of argument, and it saves a lot of pages.

This means that quoting his fudge without understanding what he meant by it or how it works (delete as applicable) isn't really a good foundation for one's own arguments, since it doesn't demonstrate a rationale.

[Graviphoton]

I know. He is certainly no favorite of mine. But he is a leading proponent in his field of research. And that is enough, surely.

 

Hawking has not discredited himself. He has just shown he can make many errors, as we all can. Its just that sometimes his errors are more recognized, because he is such a big speaker, again in his field of research.

[Sayonara]

I know. He is certainly no favorite of mine. But he is a leading proponent in his field of research. And that is enough, surely.

Well no, it's not. That is what Cap'n meant by the Appeal to Authority fallacy. Hawking's expertise cannot be vicariously applied to an argument; only his reasoning. This is because -- as you quite rightly point out -- he has made many errors, and can make more, and the quotes we borrow from him might well be examples of such. I am sure he has a very good reason for the superluminosity/uncertainty statement, but to use it as part of an argument we would need to have an understanding of that reasoning, not just a summary of the idea.

[Graviphoton]

Well, that would inexorably require a mathematical knowledge i do not have.... YET. Sure i can do a lot of physics, but just because i cannot show you his reasoning, surely doesn't make it invalid?

 

But i feel this isn't fair... For one, i don't think Hawking takes it as a summery. I think its a mathematical fact. Secondly, i have seen many people round here talk about subjects they cannot prove mathematically...

[Klaynos]

Is hawking talking about photons or virtual photons?

 

What chapter/page does he discuss this on?

 

I can't think of an uncertainty relation that would allow for photon speed to be anything other than c.

 

Well, that would inexorably require a mathematical knowledge i do not have.... YET. Sure i can do a lot of physics, but just because i cannot show you his reasoning, surely doesn't make it invalid?

 

But i feel this isn't fair... For one, i don't think Hawking takes it as a summery. I think its a mathematical fact. Secondly, i have seen many people round here talk about subjects they cannot prove mathematically...

 

Maybe you shouldn't reply to physics questions with facts then, if you're unsure of their foundations? Physics is pretty much all about maths, without the maths it is infact invalid. Falsifiable predictions and all that...

 

Well, there are number of ways a thing can escape a black hole.

One of them be can allow a photon to move at superlumnal speeds, for a short amount of time, according to the uncertainty principle.

Another way, is where you started your journey. If you start your journey from inside the black hole, then you can leave the horizon, because there is a rule which states you cannot pass the same boundary twice. So if you started your journey from inside the black hole, you can leave without any worries.

And ofcourse, normal tachyons, if they do exist, move fast enough so that the gravitational forces do not influence it on its path. They contain a negative mass, the stuff which you are talking about.

 

And there is such a thing as negative mass. Each time the Casimir Effect is in operation within the vacuum, there is a very small amount of negative mass as the result.

 

There's a couple things I want to comment on here. Firstly there is no evidence for tachyons, or any known method that they could interact with sub-lightspeed particles and therefore fall outside current physics, but having said that I've never heard it said they have negative mass? Secondly the Casimir Effect producing negative mass? I think you might be confused about something here, the casimir effect is the attraction between two conducting plates close together due to the confinement of the virtual particles between them.

[swansont]

And there is such a thing as negative mass. Each time the Casimir Effect is in operation within the vacuum, there is a very small amount of negative mass as the result.

 

That's a new one on me. There's a negative energy as compared to the zero-point, and this has been used to hypothesize effects on wormholes (hey, look: a link!) (http://authors.library.caltech.edu/9262/01/MORprl88.pdf) but when one reads that paper, one notes a lot of "it may be that" and "this may well be forbidden by some other physics" statements.

[Hypercube]

It is these virtual particles that escape from black holes. Virtual particles in a sense violate the laws of physics. Non-virtual particles do not violate the laws of physics and cannot escape from a black hole. This includes the carriers of gravity waves, non-virtual gravitons. Black holes do not emit gravity waves.

 

How can gravity itself be affected by gravity? The other three fundamental forces are not affected by themselves, or if they are it is news to me. The fact of the matter is that a graviton is gravity, to say that gravity affects gravity would be counter-intuitive at best.

[D H]

A couple of points. First and foremost, gravitons are hypothetical particles, and we don't even know how to describe these hypothetical particles other than that they (*if* they exist) are the mediators of gravity.

 

Secondly, mass, gravity, and gravitons are distinct but related concepts, just as charge, electrostatic force, and photons are distinct but related concepts. Gravitons (*if* they exist) are not gravity, just as photons are not the electrostatic force. Virtual photons are the mediators of the electrostatic force, just as virtual gravitons (*if* they exist) are the mediators of the gravitostatic force.

 

Thirdly, read these two pages from the physics FAQ: How does the gravity get out of the black hole? and Some Frequently Asked Questions About Virtual Particles.