QM + GR = black holes cannot exist

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 Carlip presents AE's position as 'ok back then' but now 'out of date'.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.

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.

 

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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.

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.

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

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

 

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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.

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.

 

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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.

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.

 

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.

 

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.

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.

 

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

 

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.

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

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.

 

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

 

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

 

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.

 

A delayed response from Prof. Moore:

 

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...

 

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.

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

 

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?

 

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.

 

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.

 

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!

 

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.