QM + GR = black holes cannot exist
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No problem.
No problem.
I disagree with that. In section 20 of Relativity: the Special and General Theory, Einstein made it clear that you cannot transform away a special (=real) gravitational field:
"We might also think that, regardless of the kind of gravitational field which may be present, we could always choose another reference-body such that no gravitational field exists with reference to it. This is by no means true for all gravitational fields, but only for those of quite special form. It is, for instance, impossible to choose a body of reference such that, as judged from it, the gravitational field of the earth (in its entirety) vanishes".
It doesn't matter what the observer thinks, spacetime is either curved, or it isn't.
That's fair enough.
Like I said, it's the "defining feature" of a gravitational field. Without it your plot doesn't get off the flat and level. But it would be a mistake to then say that the force of gravity at some location depends on the spacetime curvature at that location.
Actually the "reality" is inhomogeneous space, but that's one for another day.
Again, what you say is wrong...The curvature of spacetime in the presence of mass is indeed gravity.
And really, as I have shown in the past, referencing WIKI can be fraught with dangers and dishonesty.
eg: In a thread a while back, our old friend undefined was referencing WIKI to illustrate a point....In fact over a period of two days, he referenced two WIKI articles, to illustrate some erronious point he was making. I decided [knowing he was wrong ] to do some research into the articles he referenced. Both articles had "mysteriously" [nudge nudge, wink, wink
] been updated/revised/changed on the days he referenced them.Just saying......
In essence and without question, any spacetime curvature relates to gravity.
That's seems to be what brucep said, and that is correct.
The local apparent force of gravity is due to spacetime curvature.
The local apparent tidal force is related to the gradient of that spacetime curvature.
Yes spacetime curvature relates to gravity. If there isn't any, there is no gravitational field. But the local gravitational force depends on the spacetime gradient or "tilt", whilst the local tidal force depends on the degree of local spacetime curvature. In the room you're in, you will measure g to be 9.8 m/s² at the ceiling and at the floor. The tidal force and spacetime curvature is not detectable. But the gravity is readily detectable. Your pencil falls down at 9.8 m/s². Again see the plot of gravitational potential, which is similar to the bowling ball depiction.
CCASA image by AllenMcC see Wikipedia
[URL='http://en.wikipedia.org/wiki/Riemann_curvature_tensor']
The gradient at some location is proportional to the force of gravity at that location, whilst the degree of curvature at that location is proportional to the tidal force at that location.[/url]
And the spacetime gradient is part and parcel of the spacetime curvature.
If we have no spacetime curvature, we have no gradient, and no gravity.
But this does now appear to be an exersise in uneccessary pedant. :shrug:
No the difference is the same as the first or second derivative. If of a constant, both are zero but that does not prove them the same.
For example, the gravitational force on the moon due to the sun is stronger than the Earth's is (both go as inverse square)* but the sun's tidal stress** on the moon's rocks is much less than Earth's is as that falls off as inverse cube.
* Gravity determines the moon's orbit, which if plotted on a sheet of 8by11 inch paper, is indistinguishable from that of the earth. (Less difference than the width of the pencil's lead mark). That (essentially) the same solar gravity also acts on the Earth, so they go around the sun together on essentially the same elliptical orbit.
** The moon does not have "tides" as keeps the same face turned to Earth,*** but moon has tidal stress, almost entirely due to the "near by" earth. If the earth could magically vanish in an instant, the moon would "ring like a struck bell" until the energy stored in that stressed rock is dissipated, but to a observer on Mars, there would be no noticeable change in moon's orbit about the sun and the length of its year would not change and it would still have ~13 moon days/ year.
*** That is often referred to as a "tidal lock." The moon is slowly moving away from the Earth and its moon day is slowing growing longer, but in the distant future the moon will break free from this tidal lock, if that happens when the moon has only 9 moon days, it will for ever afterwards have 9 moon days per year.
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The problem is getting it right.
eg:
I mean according to cosmological data and accepted theory, a body is never seen to be frozen at the EH of a BH....just gradually red shifted out of viewing range.
From the local frame of the unfortunate person falling in, he indeed does cross the EH onto the Singularity and oblivion. That's science/physics/cosmology.
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All I'm saying is that Farsight was wrong in determining brucep was wrong, in inferring that spacetime curvature infers gravity.
Spacetime curvature most certainly does infer gravity, no matter how one wants to dress it up.
That's wrong. People say the infalling observer doesn't see anything unusual. But the coordinate speed of light is zero. He doesn't see anything at all, ever. It takes forever from him to see anything, and even if he fell in a billion years ago, he hasn't seen it yet. There's a schoolboy error here that has been around so long that it's taken for granted: that when you put a stopped observer in front of a stopped clock, then "in his frame" he continues to see it ticking normally. He doesn't. He's stopped and the clock is stopped. But note that this doesn't mean that black holes don't exist. It just means that the original "frozen star" black hole interpretation is the one that's right. See Kevin Brown's Formation and Growth of Black Holes for a mention of that. He doesn't favour the frozen star, but at least he refers to it:
"Incidentally, we should perhaps qualify our dismissal of the "frozen star" interpretation, because it does (arguably) give a servicable account of phenomena outside the event horizon, at least for an eternal static configuration. Historically the two most common conceptual models for general relativity have been the "geometric interpretation" (as originally conceived by Einstein) and the "field interpretation" (patterned after the quantum field theories of the other fundamental interactions). These two views are operationally equivalent outside event horizons, but they tend to lead to different conceptions of the limit of gravitational collapse. According to the field interpretation, a clock runs increasingly slowly as it approaches the event horizon (due to the strength of the field), and the natural "limit" of this process is that the clock asymptotically approaches "full stop" (i.e., running at a rate of zero). It continues to exist for the rest of time, but it's "frozen" due to the strength of the gravitational field. Within this conceptual framework there's nothing more to be said about the clock's existence."
That's all fairly reasonable stuff. It might not be what you hear about, and it should say potential rather than field, but it's legit. Now see what he says about the alternative:
"In contrast, according to the geometric interpretation, all clocks run at the same rate, measuring out real distances along worldlines in curved spacetime. This leads us to think that, rather than slowing down as it approaches the event horizon, the clock is following a shorter and shorter path to the future time coordinates. In fact, the path gets shorter at such a rate that it actually reaches the future infinity of Schwarzschild coordinate time in finite proper time. Now what? If we believe the clock is still running just like every other clock (and there's no local pathology of the spacetime) then it seems natural to extrapolate the clock's existence right past the future infinity of Schwarzschild coordinate time and into another region of spacetime."
See that future infinity? To get to the central singularity, the infalling clock goes to the end of time. The trouble is, it hasn't got there yet. And it never ever will. Black holes do exist, but the point-singularity in the middle doesn't.
You keep saying that despite all and sundry showing you are in error.
It simply depends on ones FoR.
And from the FoR of a person falling into the BH, he certainly does cross the EH, and reaches the Singularity and oblivion in a finite amount of time.
That is the accepted GR aligned physics/cosmology/science, that even school boys should learn.
But at this stage in your life, I certainly don't expect you to accept that logic.
And I certainly don't accept your illogical take on the situation, nor your claims to have a ToE.
The clock and the observer are never seen to stop...Just redshifted out of range of optical detectors from external FoR's.
From the clock and the person falling in's perspective, everything proceeds as normal [ignoring tidal gravitational effects of the BH] The person falls in, time proceeds as per normal, and the clock does not stop. Simple accepted school boy physics.
Of course he refers to it. It is simply the Newtonian Michell description of a dark star, and part of physical theoretical progress, which sensibly and logically has been superseded by the GR version.
Kevin Brown accepts that logic, as you should.
I certainly don't believe any physical infinite Singularity exists.
At some time in the future, a validated QGT, should reveal a surface of sorts, somewhere within that Planck/quantum volume.
The Hidden Reality, talks a lot about what you mentioned, but his opinion is the exact opposite on that topic it mentions thoroughly throughout the book. I didn't really like that particular book (the others where a lot better than that one), but I make a point to try and go through a lot of them even though it has information I have already read. I think it is a shame really, because a lot of pop physics books written by famous authors like that keep to mainstream science opinions, when they go into unknown aspects of things it is usually mentioned to be unknown to be proven. Things may have changed in that aspect, since you studied it.
I may regret (probably will) jumping back in to this thoroughly sidetracked thread, but....
In respect of the debate over what constitutes or defines gravity, it would be instructive to look over this thread in another forum:
https://www.physicsforums.com/threads/is-a-uniform-gravitational-field-a-gravitational-field.156168/
Those folks actually know GR and I agree with the gist of #3 there - there can be, and are, commonly used various definitions, none of which are 'absolutely right' to the exclusion of all others. What's important is to clearly define the particular definition used in a given context. A similar situation applies as to whether light speed c is or is not a variable in GR. Again, some, like myself, take the position it sensibly can be seen as a function of gravitational potential - e.g. Shapiro delay. The relational pov (the 'relativity' bit in SR/GR). Others insist that no all that matters is that locally c is an invariant. Narrow doctrinaire types tend to press the case for an exclusive definition but it's easily undermined by a simple reference to the extant literature showing a mix of true GR authorities adopting either legitimate *viewpoint*.
In respect of the debate over what constitutes or defines gravity, it would be instructive to look over this thread in another forum:
https://www.physicsforums.com/threads/is-a-uniform-gravitational-field-a-gravitational-field.156168/
Those folks actually know GR and I agree with the gist of #3 there - there can be, and are, commonly used various definitions, none of which are 'absolutely right' to the exclusion of all others. What's important is to clearly define the particular definition used in a given context. A similar situation applies as to whether light speed c is or is not a variable in GR. Again, some, like myself, take the position it sensibly can be seen as a function of gravitational potential - e.g. Shapiro delay. The relational pov (the 'relativity' bit in SR/GR). Others insist that no all that matters is that locally c is an invariant. Narrow doctrinaire types tend to press the case for an exclusive definition but it's easily undermined by a simple reference to the extant literature showing a mix of true GR authorities adopting either legitimate *viewpoint*.
Paddoboy: what you think of as "the accepted GR aligned physics/cosmology/science" is wrong. Don't be too upset about it. Some aspect of science is always wrong. If it wasn't, there wouldn't be any scientific progress.
Q-reeus: I think the "coordinate" speed of light is crucial for understanding black holes. We know that optical clocks go slower when they're lower. In the Wikipedia Shapiro delay article we can read this: "The proposed experiment was designed to verify the prediction that the speed of propagation of a light ray decreases as it passes through a region of decreasing gravitational potential". We know that if you placed light-clocks throughout an equatorial slice through the Earth and the surrounding space, your plot of light clock rates would look like the plot of gravitational potential above. And we know that there's no such thing as a negative speed, and that the force of gravity at some location depends on the local gradient in the coordinate speed of light. So we ought to know that once you're at the event horizon where the coordinate speed of light is zero, there's no more gravity. See this Baez article where you can read this:
"Einstein talked about the speed of light changing in his new theory. In his 1920 book "Relativity: the special and general theory" he wrote: "... according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity [...] cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity [Einstein means speed here] of propagation of light varies with position." This difference in speeds is precisely that referred to above by ceiling and floor observers."
It superseded the previous article written by Phil Gibbs and Steve Carlip, which ended up saying this:
“Finally, we come to the conclusion that the speed of light is not only observed to be constant; in the light of well tested theories of physics, it does not even make any sense to say that it varies.”
Note that Steve Carlip has responded to tashja's emails, see for example this. Also see this article: http://gsjournal.net/Science-Journals/Communications-Miscellaneous/Download/1863.
Q-reeus: I think the "coordinate" speed of light is crucial for understanding black holes. We know that optical clocks go slower when they're lower. In the Wikipedia Shapiro delay article we can read this: "The proposed experiment was designed to verify the prediction that the speed of propagation of a light ray decreases as it passes through a region of decreasing gravitational potential". We know that if you placed light-clocks throughout an equatorial slice through the Earth and the surrounding space, your plot of light clock rates would look like the plot of gravitational potential above. And we know that there's no such thing as a negative speed, and that the force of gravity at some location depends on the local gradient in the coordinate speed of light. So we ought to know that once you're at the event horizon where the coordinate speed of light is zero, there's no more gravity. See this Baez article where you can read this:
"Einstein talked about the speed of light changing in his new theory. In his 1920 book "Relativity: the special and general theory" he wrote: "... according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity [...] cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity [Einstein means speed here] of propagation of light varies with position." This difference in speeds is precisely that referred to above by ceiling and floor observers."
It superseded the previous article written by Phil Gibbs and Steve Carlip, which ended up saying this:
“Finally, we come to the conclusion that the speed of light is not only observed to be constant; in the light of well tested theories of physics, it does not even make any sense to say that it varies.”
Note that Steve Carlip has responded to tashja's emails, see for example this. Also see this article: http://gsjournal.net/Science-Journals/Communications-Miscellaneous/Download/1863.
I have no reason to be upset at all.
What I have said is correct and in line with present mainstream thinking, based on available evidence and data.
I am concerned though with a handful of "would be's if they could be's" and others that suffer from delusions of grandeur, culminating in claims they have a ToE.
And then further add to their delusions by claiming the scientific method and peer review are too Intransigent and hard nose to recognise this brilliance when they see it and a conspiracy is afoot to keep their brilliance from the world at large.
No, it isn't. Get used to it. Max Planck said science advances one death at a time. The world is full of physicists saying this is how it is when other physicists know it isn't, because they have the hard scientific evidence that proves it. Don't believe the "we are the mainstream" propaganda put out by former camp to such an extent that you ignore the latter whilst comforting yourself with words like "delusion".
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.
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.
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. 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.
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