QM + GR = black holes cannot exist

[paddoboy]

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.

Bingo!

 

[Farsight]

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'm afraid that's wrong. A gravitational field alters the motion of light and matter through space. A black hole doesn't suck space in or grow fat on vacuum energy. We do not live in some Chicken-Little world where the sky is falling in. Have a look at this essay where Einstein is talking about field theory. See this paragraph:

Expanding the Theory
This theory having brought together the metric and gravitation would have been completely satisfactory of the world had only gravitational fields and no electro-magnetic fields. Not it is true that the latter can be included within the general theory of relativity by taking over and appropriately modifying Maxwell's equations of the electro-magnetic field, but they do not then appear like the gravitational fields as structural properties of the space - time continuum, but as logically independent constructions. The two types of field are causally linked in this theory, but still not fused to an identity. It can, however, scarcely be imagined that empty space has conditions or states of two essentially different kinds, and it is natural to suspect that this only appears to be so because the structure of the physical continuum is not completely described by the Riemannian metric.

Note how a gravitational field is "a state of space". That state is not falling inward like it's vanishing down some plughole. It's an inhomogeneous state, modelled as curved spacetime. See this paper, and Einstein's 1920 Leyden Address:

This space-time variability of the reciprocal relations of the standards of space and time, or, perhaps, the recognition of the fact that "empty space" in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gmn), has, I think, finally disposed of the view that space is physically empty.

 

[RJBeery]

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.

Gravitational potential determines time dilation. This isn't an illusion, it's a fact. Your analogy is OK but one would 'imagine' the fish continuing to swim at their normal pace, fighting against the current; if they were wearing watches you might be thinking that their watches are not slowing down in any manner. This fails because it's actually the rate of time passing which slows down, not the apparent net distance swam. If you acknowledge that GPS must make gravitational time dilation corrections then you must also acknowledge that mass literally slows down time relative to observers distant to it. Farsight is also mistaken on this point.

 

[Farsight]

A good analogy is to imagine a fish swimming upstream in a fast flowing river.

I'm sorry paddoboy, but that's cargo-cult nonsense from the sort of people who would tell you in all seriousness that the universe is quite literally made of mathematics. You know that space isn't falling past you into the floor. You know it's nonsense.

 

[Dr_Toad]

Cargo-cult popscience trash. Don't you know another tune? This one is boring.

 

[paddoboy]

Note how a gravitational field is "a state of space". That state is not falling inward like it's vanishing down some plughole. It's an inhomogeneous state, modelled as curved spacetime. See this paper, and Einstein's 1920 Leyden Address:

It's an analogy. The same as the rubber sheet and bowling ball....or the raisin loaf.
Gravity is a state of space certainly, actually a state of spacetime curvature, which you appeared to be pedantically arguing against earlier.
Any curvature of spacetime of course can easily be Imagined to be "pulling in" the spacetime, as per the heavy bowling ball on a rubber sheet.


The following may help in visualising what actually happens....
http://casa.colorado.edu/~ajsh/home.html

 

[paddoboy]

I'm sorry paddoboy, but that's cargo-cult nonsense from the sort of people who would tell you in all seriousness that the universe is quite literally made of mathematics. You know that space isn't falling past you into the floor. You know it's nonsense.

Even more nonsensical in actual fact, could be the case of the three or four Alternative hypothesis pushers on this forum, all claiming to have a ToE, but completely fail the scientific method and peer review.
Again my view aligns with accepted mainstream models, so I let your claims of cargo cult nonsense, and where it lays, speak for itself.

 

[paddoboy]

Gravitational potential determines time dilation. This isn't an illusion, it's a fact. Your analogy is OK but one would 'imagine' the fish continuing to swim at their normal pace, fighting against the current; if they were wearing watches you might be thinking that their watches are not slowing down in any manner. This fails because it's actually the rate of time passing which slows down, not the apparent net distance swam. If you acknowledge that GPS must make gravitational time dilation corrections then you must also acknowledge that mass literally slows down time relative to observers distant to it. Farsight is also mistaken on this point.

Time dilation depends on ones FoR.
From the fish's frame of Reference, time passes as per normal.

 

[Farsight]

It's an analogy. The same as the rubber sheet and bowling ball....or the raisin loaf. Gravity is a state of space certainly, actually a state of spacetime curvature, which you appeared to be pedantically arguing against earlier. Any curvature of spacetime of course can easily be imagined to be "pulling in" the spacetime, as per the heavy bowling ball on a rubber sheet.

We're all familiar with that picture, and I've said that you can plot something like that using light clocks in an equatorial slice through the Earth and the surrounding space:



But it isn't a "pulling in". Note the energy-pressure diagonal in the stress-energy tensor. It's a "pushing out". And to imagine it you have to try to forget about the curvature of the Earth. You zoom in, like this:



Imagine each cell has a volume, and the volume varies in line with the Ricci curvature tensor. Because space is inhomogeneous, the coordinate speed of light varies and light curves, and we model it as curved spacetime.

The following may help in visualising what actually happens....

There's a lot in there. Can you be more specific?

Even more nonsensical in actual fact, could be the case of the three or four Alternative hypothesis pushers on this forum, all claiming to have a ToE, but completely fail the scientific method and peer review. Again my view aligns with accepted mainstream models, so I let your claims of cargo cult nonsense, and where it lays, speak for itself.

You believe in cargo-cult nonsense that totally contradicts general relativity, and you are kidding yourself that it's mainstream.

Farsight is also mistaken on this point.

How so? I've never said anything untoward about gravitational time dilation.

 

[Layman]

It was interesting looking at that site. I found this on http://jila.colorado.edu/~ajsh/insidebh/waterfall.html

"The picture of spacing falling into a black hole has a sound mathematical basis, first discovered in 1921 by the Nobel prize-winner Alvar Gullstrand2, and independently by the French mathematician and politician Paul Painlevé3, who was Prime Minister of France in 1917 and then again in 1925.
It is not necessary to understand the mathematics, but I do want to emphasize that, because the concept of space falling into a black hole is mathematically correct4, inferences drawn from that concept are correct.

The Gullstrand-Painlevé metric is

$$ds^2=−d{t^2}_{ff}+(dr−vdt_{ff})^2+r^2(dθ^2+sin^2θdϕ^2)$$
which is just the Schwarzschild metric expressed in a different coordinate system. The free-fall time tff is the proper time experienced by observers who free-fall radially from zero velocity at infinity. The velocity v in the Gullstrand-Painlevé metric equals the Newtonian escape velocity from a spherical mass M
$$v=−2 \sqrt{\frac{GM}{r}}$$
with a minus sign because space is falling inward, to smaller radius.
Physically, the Gullstrand-Painlevé metric describes space falling into the Schwarzschild black hole at the Newtonian escape velocity. Outside the horizon, the infall velocity is less than the speed of light. At the horizon, the velocity equals the speed of light. And inside the horizon, the velocity exceeds the speed of light. Technically, the Gullstrand-Painlevé metric encodes not only a metric, but also a complete orthonormal tetrad, a set of four locally inertial axes at each point of the spacetime. The Gullstrand-Painlevé tetrad free-falls through the coordinates at the Newtonian escape velocity.

It is an interesting historical fact that the mathematics of black holes was understood long before the physics. Einstein himself misunderstood how black holes work. He thought that the Schwarzschild geometry had a singularity at its horizon, and that the regions inside and outside the horizon constituted two separate spacetimes. I think that even today research into general relativity is too often dominated by abstract mathematical thinking at the expense of conceptual understanding."

 

[paddoboy]

You believe in cargo-cult nonsense that totally contradicts general relativity, and you are kidding yourself that it's mainstream.
.

Coming from someone who has claimed he has a ToE, and vilifies the scientific method and peer review, I find that remark rather amusing.

 

[krash661]

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

except there is ,at this moment, 23 pages showing you " real physics " which you are continuing to ignore.

 

[RJBeery]

I've never said anything untoward about gravitational time dilation.

I thought you were mistaken when you said...

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.

...because I followed that up with the fact that the light does slow down as the mass and its density increases...but that's only true from a distant source. As I copied your quote I noticed that you restricted this observation to the person holding the laser pointer. My bad!

 

[Farsight]

Physically, the Gullstrand-Painlevé metric describes space falling into the Schwarzschild black hole at the Newtonian escape velocity.

Only it doesn't. It just doesn't. The space in the room you're in is not falling down.

It is an interesting historical fact that the mathematics of black holes was understood long before the physics. Einstein himself misunderstood how black holes work. He thought that the Schwarzschild geometry had a singularity at its horizon...

I think he was right about that. Nowadays people tend to say it's a mere artefact, but I think it's something very real.

I think that even today research into general relativity is too often dominated by abstract mathematical thinking at the expense of conceptual understanding.

I'm not sure if you said that, but it's true.

...because I followed that up with the fact that the light does slow down as the mass and its density increases...but that's only true from a distant source. As I copied your quote I noticed that you restricted this observation to the person holding the laser pointer. My bad!

Not so your bad. You perhaps missed something here. It's rather counterintuitive, but it's crucial. You know gravitational time dilation reduces as you ascend? You know how Einstein said a curvature of rays of light can only occur when the speed of light varies with position? You know how an optical clock goes faster if you raise it up? That optical clock goes faster because the coordinate speed of light increases. Because light goes faster. And as the ascending photon goes up, it doesn't slow down. It goes faster and faster. That's the nub of Einstein's GR that you never ever hear about.

Time for bed.

 

[RJBeery]

Not so your bad. You perhaps missed something here. It's rather counterintuitive, but it's crucial. You know gravitational time dilation reduces as you ascend? You know how Einstein said a curvature of rays of light can only occur when the speed of light varies with position? You know how an optical clock goes faster if you raise it up? That optical clock goes faster because the coordinate speed of light increases. Because light goes faster. And as the ascending photon goes up, it doesn't slow down. It goes faster and faster. That's the nub of Einstein's GR that you never ever hear about.

Yes, the distant observer would say that the speed of light increases as it ascends. I agree with you. This is the same thing as saying the speed of light decreases as it descends, agreed? But when you said

I make the planet evendenser 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?

I was answering. It's because at that point where the black hole comes into existence coordinate time and the speed of light have stopped.

 

[PhysBang]

Note how a gravitational field is "a state of space". That state is not falling inward like it's vanishing down some plughole. It's an inhomogeneous state, modelled as curved spacetime. See this paper, and Einstein's 1920 Leyden Address:

Note how Farsight has quotation marks around "a state of space", but the original does not contain that phrase. Indeed, in the very passage that Farsight quotes, Einstein refers to gravity as "structural properties of the space - time continuum", a direct contradiction to Farsight's claim that, according to Einstein, gravity is a property of space, not spacetime.

 

[brucep]

It was interesting looking at that site. I found this on http://jila.colorado.edu/~ajsh/insidebh/waterfall.html

"The picture of spacing falling into a black hole has a sound mathematical basis, first discovered in 1921 by the Nobel prize-winner Alvar Gullstrand2, and independently by the French mathematician and politician Paul Painlevé3, who was Prime Minister of France in 1917 and then again in 1925.
It is not necessary to understand the mathematics, but I do want to emphasize that, because the concept of space falling into a black hole is mathematically correct4, inferences drawn from that concept are correct.

The Gullstrand-Painlevé metric is

$$ds^2=−d{t^2}_{ff}+(dr−vdt_{ff})^2+r^2(dθ^2+sin^2θdϕ^2)$$
which is just the Schwarzschild metric expressed in a different coordinate system. The free-fall time tff is the proper time experienced by observers who free-fall radially from zero velocity at infinity. The velocity v in the Gullstrand-Painlevé metric equals the Newtonian escape velocity from a spherical mass M
$$v=−2 \sqrt{\frac{GM}{r}}$$
with a minus sign because space is falling inward, to smaller radius.
Physically, the Gullstrand-Painlevé metric describes space falling into the Schwarzschild black hole at the Newtonian escape velocity. Outside the horizon, the infall velocity is less than the speed of light. At the horizon, the velocity equals the speed of light. And inside the horizon, the velocity exceeds the speed of light. Technically, the Gullstrand-Painlevé metric encodes not only a metric, but also a complete orthonormal tetrad, a set of four locally inertial axes at each point of the spacetime. The Gullstrand-Painlevé tetrad free-falls through the coordinates at the Newtonian escape velocity.

It is an interesting historical fact that the mathematics of black holes was understood long before the physics. Einstein himself misunderstood how black holes work. He thought that the Schwarzschild geometry had a singularity at its horizon, and that the regions inside and outside the horizon constituted two separate spacetimes. I think that even today research into general relativity is too often dominated by abstract mathematical thinking at the expense of conceptual understanding."

The Schwarzschild geometry has a coordinate singularity at r=2M. Einstein would have to be as clueless as you not to understand Schwarzschilds solution. The rain coordinates don't predict space is falling into the black hole. You're living proof that conceptual understanding can be misinformed nonsense when you don't understand what you're talking about.

 

[paddoboy]

Note how Farsight has quotation marks around "a state of space", but the original does not contain that phrase. Indeed, in the very passage that Farsight quotes, Einstein refers to gravity as "structural properties of the space - time continuum", a direct contradiction to Farsight's claim that, according to Einstein, gravity is a property of space, not spacetime.

Nice pickup.
Hmmm, not only misinterpretations, phrases out of context, but now claiming quotes attributed to people that weren't.
Not that I see much difference between space and spacetime, although I prefer the latter.

I disagree with that..

Only it doesn't. It just doesn't. The space in the room you're in is not falling down..

I don't agree with that.

You having been telling us all what you agree and disagree with for ages...You have also told us you have a ToE.....
That does not make either claim as factual or true.

 

[paddoboy]

It was interesting looking at that site. I found this on http://jila.colorado.edu/~ajsh/insidebh/waterfall.html

"The picture of spacing falling into a black hole has a sound mathematical basis, first discovered in 1921 by the Nobel prize-winner Alvar Gullstrand2, and independently by the French mathematician and politician Paul Painlevé3, who was Prime Minister of France in 1917 and then again in 1925.
It is not necessary to understand the mathematics, but I do want to emphasize that, because the concept of space falling into a black hole is mathematically correct4, inferences drawn from that concept are correct.

The Gullstrand-Painlevé metric is

$$ds^2=−d{t^2}_{ff}+(dr−vdt_{ff})^2+r^2(dθ^2+sin^2θdϕ^2)$$
which is just the Schwarzschild metric expressed in a different coordinate system. The free-fall time tff is the proper time experienced by observers who free-fall radially from zero velocity at infinity. The velocity v in the Gullstrand-Painlevé metric equals the Newtonian escape velocity from a spherical mass M
$$v=−2 \sqrt{\frac{GM}{r}}$$
with a minus sign because space is falling inward, to smaller radius.
Physically, the Gullstrand-Painlevé metric describes space falling into the Schwarzschild black hole at the Newtonian escape velocity. Outside the horizon, the infall velocity is less than the speed of light. At the horizon, the velocity equals the speed of light. And inside the horizon, the velocity exceeds the speed of light. Technically, the Gullstrand-Painlevé metric encodes not only a metric, but also a complete orthonormal tetrad, a set of four locally inertial axes at each point of the spacetime. The Gullstrand-Painlevé tetrad free-falls through the coordinates at the Newtonian escape velocity.

It is an interesting historical fact that the mathematics of black holes was understood long before the physics. Einstein himself misunderstood how black holes work. He thought that the Schwarzschild geometry had a singularity at its horizon, and that the regions inside and outside the horizon constituted two separate spacetimes. I think that even today research into general relativity is too often dominated by abstract mathematical thinking at the expense of conceptual understanding."

The point to remember is that it is a useful analogy. Spacetime is not a river nor is light a fish. Spacetime is not a rubber sheet or a raisin loaf either, but each are analogous as to how gravity, light and BH's appear to operate.
The only thing we can be sure of, is that space exists, time exists, and as a consequence, spacetime exists.

 

[tashja]

Hi, Farsight. Here's Prof. Moore's reply to your thought experiment:

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?

Prof. Moore:

This is a good example of how intuitive models can go astray.

The argument presumes that the light signal does not "slow down," but what exactly does that mean? An observer at rest relative to the star will always measure the outgoing light signal to have speed c *locally,* (that is, as the flash passes through a laboratory that is very small compared to scale over which spacetime is locally curved), but to talk about the speed of a signal emerging from the planet's surface and going all the way to infinity, one needs a *global* coordinate system (one that applies at all positions in spacetime, such as the Schwarzschild coordinate system) to talk about the signal's speed at various points. An observer using such a coordinate system will find that the light flash will move *slower* than c close to the planet's surface than it does at at infinity. This does not contradict the previous results, because time runs more slowly for observers close to the planet's surface than for those higher up, so what looks like something moving with speed c to an observer close to the surface looks like something moving slower to someone whose clock is running faster.

As the planet's mass approaches the black hole limit, the signal emitted from the surface will seem to move more and more slowly away from the surface (and will also be seen to be increasingly red-shifted as observed from infinity). When the surface of the planet coincides with the black hole's event horizon, the signal will stop moving outward from the surface (and the redshift observed at infinity will go to infinity). So light no longer escapes.

This also does not contradict the statement about an observer at rest on the surface seeing the signal to have speed c, because as event horizon moves beyond the planet's surface, that surface can no longer remain at rest, but in fact must go to r = 0 in a finite time (as measured by an observer on the surface), just as surely as the past must go towards the future. Even then, an observer on the surface will *still* see the light moving outward at speed c, but from the perspective of the global coordinate system, it is simply that the observer is falling faster toward r = 0 than the signal is.

To understand all this fully, I strongly recommend that the questioner take a course in general relativity!


Best wishes, Tom M.