QM + GR = black holes cannot exist

[Q-reeus]

Q-reeus: physics is a battle of ideas. It really is. Far more than most people appreciate. And I'm afraid his pov isn't legitimate, because it's self-contradictory.

Not really. Carlip presents AE's position as 'ok back then' but now 'out of date'. The idea is to standardize thinking in terms of constant c but varying spacetime paths. I prefer the 'old' thinking as intuitively superior - as do many practicing physicists. Similar remarks apply to invariant mass vs 'relativistic mass', though there the 'hearts and minds' battle is fapp now over. Conformity has been vigorously pushed but that doesn't make the 'old' concept somehow intrinsically wrong - the eradication program's impetus seems to have been that the 'old' concept is more prone to misapplication/misinterpretation.

The situation is something like the spacetime curvature that's either there or it isn't. The physics is either right or it isn't. And it matters that it's right.

Spacetime curvature is either there or not, but as to what defines a gravitational field is as per thread I referenced to, not near so cut-and-dried and strictly defined as some insist.

 

[Farsight]

Not really. Carlip presents AE's position as 'ok back then' but now 'out of date'. The idea is to standardize thinking in terms of constant c but varying spacetime paths.

I don't agree with that. I think Carlip is saying Einstein was wrong when he wasn't. Have a read of http://arxiv.org/abs/0705.4507 where Magueijo and Moffat say the locally measured speed of light is constant by definition, and a tautology. I agree with that. You can find me saying we use the motion of light to define the second and the metre and then use them to measure the motion of light.

I prefer the 'old' thinking as intuitively superior - as do many practicing physicists. Similar remarks apply to invariant mass vs 'relativistic mass', though there the 'hearts and minds' battle is fapp now over.

Just to demonstrate what a rich seam all this provides: when you drop a brick some of its mass-energy is converted into kinetic energy. After this is dissipated, the brick weighs less. Check out the mass deficit. Invariant mass... varies.

Conformity has been vigorously pushed but that doesn't make the 'old' concept somehow intrinsically wrong - the eradication program's impetus seems to have been that the 'old' concept is more prone to misapplication/misinterpretation.

IMHO in certain respects, incorrect physics has been vigorously pushed.

Spacetime curvature is either there or not, but as to what defines a gravitational field is as per thread I referenced to, not near so cut-and-dried and strictly defined as some insist.

I don't think that's such a big issue myself.

 

[PhysBang]

No, it isn't. Get used to it. Max Planck said science advances one death at a time.

Yes, he said this, but your argument from authority fails here because this is a historical claim that can be tested. And people have tried to test it and found it to be false.

Farsight, just because you can't convince physicists doesn't mean that physicists cannot be convinced. The problem is you, not some vast conspiracy of incompetent physicists. You don't even read your own citations, let alone the work of your quasi-religious icon Einstein. If you would take the time to learn physics, at that time you might be able to convince physicists.

See what I said to Q-reeus about Baez and the speed of light? Steve Carlip is/was suffering from the delusion that the speed of light is constant. To such an extent that he contradicted himself, saying Einstein said the speed of light varied which made sense, and then saying it didn't make sense to say the speed of light varied. I pointed this out to Don Koks, and he's rewritten the Baez article. I don't know if Steve Carlip knows about this, and is cool about it. I hope so. But I suspect he doesn't, because if he did he'd soon work out that the speed of light can't go less than zero, so the force of gravity stops at the event horizon.

Farsight, the article did not make sense to you because you can't do any physics. You don't understand what it means to assign a velocity in classical physics, let alone in the relativistic context, so when people discuss the somewhat sophisticated idea of how to define a speed, you cannot follow.

Again, the problem is not a vast conspiracy of physicists who are not competent, the problem is you.

 

[Q-reeus]

I don't agree with that. I think Carlip is saying Einstein was wrong when he wasn't. Have a read of http://arxiv.org/abs/0705.4507 where Magueijo and Moffat say the locally measured speed of light is constant by definition, and a tautology. I agree with that. You can find me saying we use the motion of light to define the second and the metre and then use them to measure the motion of light.

Agree with their tautology comment, but that article on my quick reading has nothing to say about c as a function of gravity a la Einstein's position, but more exotic ideas bringing in additional fields of nature. And where any postulated variation is only detectable in terms of say fine structure constant variation or similar.

Just to demonstrate what a rich seam all this provides: when you drop a brick some of its mass-energy is converted into kinetic energy. After this is dissipated, the brick weighs less. Check out the mass deficit. Invariant mass... varies.

What that scenario highlights is not some failure of invariant mass (defined strictly locally in the brick rest frame), but just illustrates mass-energy equivalence. Of course one expects a net mass reduction - of combined planet-brick system - after heat has radiated away. There has been a mini gravitational collapse. But that coordinate determined net deficit won't equal the much smaller deficit in principle observed by weighing the brick, via a string attached, from the higher potential elevation where it was dropped from. And if weighing at the brick's lower elevation, no change is observed - invariant brick mass as defined holds good.

 

[PhysBang]

Agree with their tautology comment, but that article on my quick reading has nothing to say about c as a function of gravity a la Einstein's position, but more exotic ideas bringing in additional fields of nature. And where any postulated variation is only detectable in terms of say fine structure constant variation or similar.

The nature of that Magueijo and Moffat article has been pointed out to Farsight many times. Please do not make the mistake of thinking that Farsight has read or can understand that article, Farsight has demonstrated that he has no interest in the work of others unless they can be used to create crude arguments from authority for whatever position Farsight happens to hold at the moment.

 

[Farsight]

Agree with their tautology comment, but that article on my quick reading has nothing to say about c as a function of gravity a la Einstein's position, but more exotic ideas bringing in additional fields of nature. And where any postulated variation is only detectable in terms of say fine structure constant variation or similar.

Yep. All I meant to point out with that was the tautology. By the by, I've said previously that Magueijo has proposed that the speed of light was faster in the early universe, whilst I think it was slower.

What that scenario highlights is not some failure of invariant mass (defined strictly locally in the brick rest frame), but just illustrates mass-energy equivalence. Of course one expects a net mass reduction - of combined planet-brick system - after heat has radiated away. There has been a mini gravitational collapse. But that coordinate determined net deficit won't equal the much smaller deficit in principle observed by weighing the brick, via a string attached, from the higher potential elevation where it was dropped from. And if weighing at the brick's lower elevation, no change is observed - invariant brick mass as defined holds good.

I don't accept that. The kinetic energy came from the brick, not from the field, or the system. There is no magical process by which the brick's kinetic energy streams in from the surrounding space. Conservation of energy applies. Potential energy is converted into kinetic energy. The string is not relevant, we don't say the brick's mass has changed just because it's now at a location where the local slope in gravitational potential and hence the "force" of gravity is different. I think it's important to remember this:
1) Sometimes you measure a change because the thing you measure changed. As you would expect.
2) Sometimes you measure a change because you and your measuring equipment changed, and the thing you measure didn't change. Like photon energy.
3) Sometimes you don't measure a change because you and your measuring equipment didn't change, or nor did the thing you're measuring. Nothing happened.
4) Sometimes you don't measure a change because you and your measuring equipment did change, and so did the thing you're measuring. Like the mass of the brick.

 

[Dr_Toad]

That's wrong.

I don't accept that.

Blah, blah. Obviously you don't accept physics. Why belabor it, since we all know it?

 

[PhysBang]

Yep. All I meant to point out with that was the tautology.

Like I said, Farsight is only interested in cherry-picking quotations, not the actual science involved in the article, which he has not read and cannot understand.

By the by, I've said previously that Magueijo has proposed that the speed of light was faster in the early universe, whilst I think it was slower.

And the argument for that is fascinating: textual analysis and no physics.

I don't accept that. The kinetic energy came from the brick, not from the field, or the system.

Of course, why attribute properties of a physical system to the physical system?

Farsight, I have said it before and I'll say it again: take the time to learn physics, including to work through some physics problems. It can be quite rewarding.

 

[QuarkHead]

Oh dear, this is getting boring.

Look, as much as I disapprove of Farsight's appeals to (sometimes dodgy) authority, as much as it seems he quotes these so-called authorities out of context, as much as I agree his lack of expertise in differential geometry leads him to wrong conclusions about space structure, as much as I find his self-proclamation as an "insightful expert" somewhat distasteful, let me say this.....

He at least tries to keep the discussion strictly on what he calls "physics". Yet his critics, who claim to know more about "real physics" than he have not (in this thread at least) demonstrated this knowledge, to any significant degree but have merely resorted to puerile ad homina.

What purpose is served thereby?

Boring, boring, boring

 

[Farsight]

Don't let those "critics" distract you from an interesting discussion, QuarkHead.

 

[PhysBang]

What purpose is served thereby?

Good question.

Since Farsight is fairly dogged in his methods, if he was actually inspired to learn physics, it would be interesting to see what he could actually accomplish. I, for one, think that he could actually produce something of value.

Failing that, it is nice to see some correction of false statements.

 

[tashja]

A delayed response from Prof. Moore:

Prof. Moore: Sorry to be so delayed in responding -- I was out of town.

Billy T: Do two photons traveling side-by-side, only one micron apart, attract each other via their gravitational interaction (by their warp of space time) by their ("stress-energy tensor) or any other terms you prefer?

This is not a trivial question to answer. The stress-energy tensor is meant to handle continuous distributions of matter and energy, not point particles. One might treat the photons as delta functions or as gaussian wave packets and use calculations based on the weak-field limit to try to address the issue, at least approximately. But this would be a complicated calculation that I have not done, and I am not sure that I can intuit the answer. Packets of energy moving at the speed of light would produce strong gravitomagnetic effects as well as an attractive effect, and I am not sure which will dominate.

Billy T:Assuming that you are saying {with (1)} that photons do mutually attract, is it conceptually possible that a Black Hole could have no rest mass as it is only "zillions of photons" orbiting the center "like a swarm of bees" due to the mutual warping of space about that point?

I think that the answer to this is more clearly no, at least as the questioner has imagined it. One of the key features of a (Schwarzschild) black hole is that the timelike and lightlike worldlines that material particles follow all end at the singularity at the center (r = 0 becomes the "future" of all such worldlines). Therefore a photon inside the event horizon cannot orbit in the black hole's interior "like a swarm of bees": photons (along with everything else) very quickly end up at r = 0. Photons can remain at rest exactly *on* the event horizon, but this is an unstable equilibrium position, so a shell of such photons could not provide the energy to form a stable black hole: such a shell would rapidly dissipate both inward or outward.

That being said, I have neither done nor seen a calculation involving the spherical collapse of a photon "gas" consisting of inward-directed photons. This might be an interesting calculation to do, and could yield different behavior than the formation of a Schwarzschild black hole, even in the high-energy limit. But such a process would also be highly artificial and not occur in nature.



Much of what I saw on the parts of the thread I read was nonsense. General relativity is subtle and (in my experience) arguments based on intuitive models are likely to be misleading at best and are "not even wrong"* at worst. Definitively answering the questions of the type raised requires more careful framing of the question itself within the context of the tools that general relativity provides, and then very careful and (usually very complicated) calculation. In many cases, the answers to even deceptively simple questions requires a numerical solution, and numerical solutions are tricky to set up and often difficult to interpret. So I would distrust any argument based on intuitive reasoning (including my own) without firm support by a detailed calculation.


With regard to the paper that sparked the forum discussion: I looked at it, and quickly realized that I would (a) have to carefully go through all of the calculations myself and (b) carefully read and evaluate the literature on Hawking radiation before I could make a decision about whether I believed the results or not. I did not have time to do all that work, but that work is precisely the job of the paper's reviewers. Even if the paper gets published, I am sure that it will remain controversial and will get a lot of discussion by theorists, and out of that discussion, clarity will emerge. But this will take months or years. So I would counsel patience!


Sorry that I cannot be more helpful,

Tom M.

*http://en.wikipedia.org/wiki/Not_even_wrong

 

[Layman]

No, it isn't. Get used to it. Max Planck said science advances one death at a time.

When you two keel over, maybe two people could start a real discussion about how Einstein was wrong and light actually doesn't even vary and stays constant in a gravitational field as well...

 

[paddoboy]

No, it isn't. Get used to it. Max Planck said science advances one death at a time..

I don't need to get used to anything Farsight. I have no excessive ego to bruise and no delusions of grandeur to deflate, and I'm certainly not delusional enough to claim I have a ToE.
What I have said aligns with accepted mainstream physics, and on that I rest my case.

And in accordance with what I wrote, he's entitled to his pov which is legitimate as it's defined. The problem in the more general case is in insisting, as some here do, that one or more other pov are somehow automatically 'illegitimate'. As long as the physics turns out right either way, interpretational wars are imo best shunned.

Thanks and well put, and that's all my contention has been about...the legitimacy of my PoV.

 

[Farsight]

Good stuff tashja. The responses you've been getting have been interesting. If you can, please can you ask Prof Moore and others why doesn't the light get out?

You're standing on a gedanken planet holding a laser pointer straight up. The light doesn't curve round, or slow down as it ascends, or fall down. It goes straight up. Now I wave my magic wand and make the planet denser and more massive. The light still doesn't curve round, or slow down as it ascends, or fall down. I make the planet even denser and more massive. The light still doesn't curve round, or slow down as it ascends, or fall down. I make the planet even denser and more massive, and take it to the limit such that it's a black hole. At no point did the light ever curve round, or slow down as it ascends, or fall down. So why doesn't the light get out?

 

[RJBeery]

Good stuff tashja. The responses you've been getting have been interesting. If you can, please can you ask Prof Moore and others why doesn't the light get out?

You're standing on a gedanken planet holding a laser pointer straight up. The light doesn't curve round, or slow down as it ascends, or fall down. It goes straight up. Now I wave my magic wand and make the planet denser and more massive. The light still doesn't curve round, or slow down as it ascends, or fall down. I make the planet even denser and more massive. The light still doesn't curve round, or slow down as it ascends, or fall down. I make the planet even denser and more massive, and take it to the limit such that it's a black hole. At no point did the light ever curve round, or slow down as it ascends, or fall down. So why doesn't the light get out?

Qualitatively, the light's ascension DOES slow down as the mass increases, at least from the distant observer's point of view. If this wasn't true then there would be no time dilation caused by gravity, agreed?

 

[paddoboy]

When you two keel over, maybe two people could start a real discussion about how Einstein was wrong and light actually doesn't even vary and stays constant in a gravitational field as well...

If you mean my opinion as opposed to Farsight's then obviously you have lost sight of something very important.
It's forums like this that are in general the domain of amateurs, lay people, and those that have more then a passing Interest in the sciences. Before I continue with my rant, apologies to the few professionals we do have on board. I'm sure you know who you are.
My contention though, is that in the main, opinions such as Farsight's [ and my own] are not affecting or adding or subtracting from the mainstream scientific based opinions and theories.
The working scientist, physicist, astronomers, cosmologists, biologists, etc, are at the coal face making discoveries, investigating phenomena, formulising and Interpreting data, and then via the scientific methodology undergo peer review for those discoveries, and interpretations of data.
I really seriously doubt that they have the time to have more then a passing Interest [if any] in public forums such as this, unlike the time that amateurs such as myself, and Farsight do.

In other words, the opinions put as facts on this forum, hold no relevance to the opinions based on data and evidence that govern mainstream sciences in all their disciplines.

Again, apologies to the very few obvious professionals that in the course of their work, can find the time to frequent this place.
You know who you are, I have a good idea who you are, and most of the forum also have a good idea.

 

[Layman]

You're standing on a gedanken planet holding a laser pointer straight up. The light doesn't curve round, or slow down as it ascends, or fall down. It goes straight up. Now I wave my magic wand and make the planet denser and more massive. The light still doesn't curve round, or slow down as it ascends, or fall down. I make the planet even denser and more massive. The light still doesn't curve round, or slow down as it ascends, or fall down. I make the planet even denser and more massive, and take it to the limit such that it's a black hole. At no point did the light ever curve round, or slow down as it ascends, or fall down. So why doesn't the light get out?

They have been saying more recently light doesn't get out because it is actually the space itself that is being drawn in faster than light.

 

[Layman]

If you mean my opinion as opposed to Farsight's then obviously you have lost sight of something very important.
It's forums like this that are in general the domain of amateurs, lay people, and those that have more then a passing Interest in the sciences.

I think you would be surprised how many professionals visit different physics forums. They just don't announce themselves and let people know who they are. The nerdiest of the nerds do what nerds do...

You two are not the only ones. I am actually tired of reading about this same thing anytime I go to mostly any scientific forum. It is always the same. Then I am sitting here thinking there needs to be more invariance of light in other situations like in gravitational fields. The arguments about this have gotten me so confused about the subject that I don't even remember anymore if it is mainstream or actually scientifically valid to say that it actually does change in a gravitational field or not!

 

[paddoboy]

Good stuff tashja. The responses you've been getting have been interesting. If you can, please can you ask Prof Moore and others why doesn't the light get out?

You're standing on a gedanken planet holding a laser pointer straight up. The light doesn't curve round, or slow down as it ascends, or fall down. It goes straight up. Now I wave my magic wand and make the planet denser and more massive. The light still doesn't curve round, or slow down as it ascends, or fall down. I make the planet even denser and more massive. The light still doesn't curve round, or slow down as it ascends, or fall down. I make the planet even denser and more massive, and take it to the limit such that it's a black hole. At no point did the light ever curve round, or slow down as it ascends, or fall down. So why doesn't the light get out?

The speed of light remains the same.
A good analogy is to Imagine a fish swimming upstream in a fast flowing river.
Once the river's flow equals the velocity of the fish swimming against it, the fish will appear to be stationary to an observer. When the flow exceeds the fish's velocity upstream, the fish will appear to be going backwards with that flow, although still maintaining its swimming speed.