I am the first in the world

[sol invictus]

Please don't try to suggest that I'm advancing wild hypotheses without scientific support.

That's precisely what you are doing.

Those coordinate systems are abstract mathematical artefacts. Black holes exist, space exists, light exists, gravitational fields exist. All these things are manifest. Coordinate systems are not.

That's exactly the point. Coordinate systems are human conventions, they have no bearing on reality. You can choose any coordinates you like - and it's only in the coordinate system you insist on always using that light slows down or time stops at the horizon. In an infinite number of other coordinate systems, all equally as valid as yours, nothing unusual happens at the horizon.

 

[Farsight]

Since you bring it up again, Farsight, how's that with gravitomagnetism and your "eleastic response" again?

Could you this time detail this "eleastic response", please?

What's with the eleastic? See this article re gravitomagnetism.

 

[Farsight]

Farsight's like the guy who's got his atlas open to a chart that shows only the 48 contiguous states, and is using that chart to deny the existence of Hawaii and Alaska. When we tell him the next page contains a chart of all 50 states plus Mexico and Canada, he refuses to look.

I'm not, you are. I'm showing you the variable speed of light, you're refusing to look, preferring instead to wallow in mathematical abstraction and erudition and to believe that for a stopped observer a stopped clock carries on ticking. And please, spare me your not-qualified to judge pomposity. You have no counter-argument, and it shows.

 

[Farsight]

...As for Farsight, I think Upton Sinclair said the right thing. "It is difficult to get a man to understand something, when his salary ego depends upon his not understanding it."

Look in the mirror, ben. You have no counterargument, remember?

 

[Roboramma]

Look in the mirror, ben. You have no counterargument, remember?

It's pretty clear that he does, and I don't understand why you quote that bit rather than addressing it.

 

[Daylightstar]

What's with the eleastic? See this article re gravitomagnetism.

No, your 'elastic response'.

I did not ask you to again post a link to a story which does not detail your 'elastic response' with respect to space ('that black stuff between the stars') sustaining/holding/supporting waves and fields.

I asked you to detail your 'elastic response', your claimed 'method' for space ('that black stuff between the stars') to sustain/hold/support waves and fields.
If you'd be so kind, please do so now.

 

[ben m]

Look in the mirror, ben. You have no counterargument, remember?

Oh, right, I forgot. Thanks for reminding me. I was distracted by the GR textbook on my desk, which contains such sentences as this:

In summary, there is nothing strange about the geometry at the dotted line; all the singularity lies in the coordinate system ... no confusion should be permitted to arise from the accidental circumstance that the t coordinate attains an infinite value on the dotted line.

I've got some niggling feeling that this is relevant, given that your argument revolves around something to do with v=0, and that when t=infinity it's true that 1/t=0, but ... well, I can't put my finger on it. Someone of my feeble intellect could never build that into something as high-falutin' as an actual counter-argument.

Maybe if I had the textbook on an actual counter. Would that help?

 

[ctamblyn]

Stop talking about stopping time. Make the leap to stopping light. There's nothing bizarre or mysterious. Think back to the optical clocks losing synchronisation at different elevations, simplified to parallel-mirror light clocks.

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One light beam is going slower than the other, and c = √(1/ε₀μ₀). The vacuum impedance of space Z₀ = √(μ₀/ε₀) is increasing. Increase it so that it totally impedes the motion of light, and you stop light. Then nothing moves and clocks don't tick. Waves can't propagate through space any more. It's that simple.

I seem to remember having this conversation once before, but I could be thinking of someone else. I think I remember you suggesting some time back that gravity could be described in terms of a sort of "refractive index" of space.

I hope one of the professionals here will correct me if I'm wrong, but if I understand this correctly your hypothesis implies that gravity could be described completely by a single scalar field. If so then your wrong to say "it's that simple", since AFAIK there are no successful scalar theories of gravity.

For example, Nordström (who knew what he was doing) tried to formulate such a theory back in 1913. It suffers with a number of problems:

• It predicts that light is not bent by gravitational fields (in contradiction to observation).
• It predicts that the perihelion of Mercury's orbit will lag by 7 arcseconds per year, instead of advancing by 43 (contradicting observation).
• It gets the Shapiro time delay prediction wrong (contradicting observation once more).

Since this matter is anything but "simple", perhaps you could actually show that your theory fares better than Nordström's when applied to these classical tests?

 

[Farsight]

That's precisely what you are doing.

No I'm not. I'm advocating the "frozen star" concept that dates back to Oppenheimer as mentioned here: http://arxiv.org/abs/1003.1359 . The author of this paper says "matter can indeed fall across the event horizon within a finite time" but disagreeing with that really isn't some wild hypothesis. Come on sol, you do yourself a disservice by trying to portray it as so.

That's exactly the point. Coordinate systems are human conventions, they have no bearing on reality. You can choose any coordinates you like - and it's only in the coordinate system you insist on always using that light slows down or time stops at the horizon. In an infinite number of other coordinate systems, all equally as valid as yours, nothing unusual happens at the horizon.

I'm not choosing any coordinate system, I'm pointing out the hard scientific evidence of optical clocks and giving a chain of logic saying the speed of light really does vary like Einstein said, and that light doesn't get out of that massive thing at the centre of the galaxy with stars swinging around it for a simple reason. You know full well that light going straight up from a black hole doesn't curve back down, just as light passing between two stars isn't curved. The light doesn't get out because it's stopped. You don't need a coordinate system to see the bleedin' obvious that leads you to this: parallel-mirror light clocks at different elevations lose synchronisation because the speed of light isn't constant. Not the coordinate speed of light isn't constant. You've got light moving between two mirrors, that's what's actually there, not the human convention of a non-inertial reference frame, and not time flowing. Just light, moving through the space between mirrors.

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[ben m]

No I'm not. I'm advocating the "frozen star" concept that dates back to Oppenheimer as mentioned here: http://arxiv.org/abs/1003.1359 . The author of this paper says "matter can indeed fall across the event horizon within a finite time" but disagreeing with that really isn't some wild hypothesis. Come on sol, you do yourself a disservice by trying to portray it as so.

Did you read the paper? It quotes Oppenheimer himself agreeing with us and disagreeing with you.

The total time of collapse for an observer comoving with the stellar matter is finite ... An external observer (O hereafter) sees the star
asymptotically shrinking to its gravitational radius.

Yes, Farsight, it is a wild hypothesis to imagine that some parts of GR are correct except that this one particular coordinate-singularity is "real" and observer-independent. That's standard crackpot physics.

 

[Farsight]

It's pretty clear that he does, and I don't understand why you quote that bit rather than addressing it.

Would you like to reiterate his pretty clear counter-argument? Didn't think so.

I asked you to detail your 'elastic response', your claimed 'method' for space ('that black stuff between the stars') to sustain/hold/support waves and fields. If you'd be so kind, please do so now.

I can't detail it without going into electromagnetic four-potential and displacement current and the nature of the photon, and that would take a long time. Please start a thread if you want me to talk about it it. But meanwhile have at displacement current on wiki and note the Maxwell quotes where elastic is mentioned:

"The author of this method of representation does not attempt to explain the origin of the observed forces by the effects due to these strains in the elastic solid, but makes use of the mathematical analogies of the two problems to assist the imagination in the study of both".

"These relations are independent of any theory about the mechanism of dielectrics; but when we find electromotive force producing electric displacement in a dielectric, and when we find the dielectric recovering from its state of electric displacement...we cannot help regarding the phenomena as those of an elastic body, yielding to a pressure and recovering its form when the pressure is removed."

Also see Einstein talking about the history of field theory in 1929. Here's a few snippets:

"People slowly accustomed themselves to the idea that the physical states of space itself were the final physical reality...

It is only natural that attempts were made to represent the material particles as structures in the field...

But the special theory of relativity showed that this causal correlation corresponds to an essential identity of the two types of field. In fact, the same condition of space, which in one coordinate system appears as a pure magnetic field, appears simultaneously in another coordinate system in relative motion as an electric field, and vice versa..."

Or see LIGO where you can read this:

"When large masses move suddenly, some of this space-time curvature ripples outward, spreading in much the way ripples do the surface of an agitated pond".

Note that space isn't a substance, it isn't some elastic solid in the usual sense. But waves do propagate through it. We know that electromagnetic waves do, and we're confident that gravitational waves do too. And LIGO is intended to detect a transient length-change in the arms of the interferometer:

"The space-time ripples cause the distance measured by a light beam to change as the gravitational wave passes by".

If the distance changes, the thing that's waving is space. And the wave can only propagate if space somehow "kicks back" via some kind of elastic response.

 

[sol invictus]

The author of this paper says "matter can indeed fall across the event horizon within a finite time" but disagreeing with that really isn't some wild hypothesis.

Of course it is. It disagrees with all established science, including the very same science you claim to be using to reach your conclusion.

I'm not choosing any coordinate system

Then you should be happy with a choice of coordinates in which the coordinate speed of light does nothing unusual at the horizon. But you're not, you refuse to accept that. Ergo, you're insisting on one specific coordinate system. That's precisely the contrary of the fundamental truth general relativity is based on - that choices of coordinates are meaningless and arbitrary.

 

[ben m]

I'm not choosing any coordinate system, I'm pointing out the hard scientific evidence ... You've got light moving between two mirrors, that's what's actually there

You're such a GR novice that you don't even notice when you're using a coordinate system.

 

[ctamblyn]

No I'm not. I'm advocating the "frozen star" concept that dates back to Oppenheimer as mentioned here: http://arxiv.org/abs/1003.1359 . The author of this paper says "matter can indeed fall across the event horizon within a finite time" but disagreeing with that really isn't some wild hypothesis. Come on sol, you do yourself a disservice by trying to portray it as so.

Um, the paper you linked to disagrees with you explicitly. From pp. 5-6:

...
Finally these questions are answered definitely and the above “frozen star” paradox is solved completely by Liu & Zhang[4]. As shown in Figs. 2 and 3 taken from Ref. 4, matter cannot accumulate outside R_H, due to the increase of R_H which swallows the matter falling in. The fundamental reason for the asymptotic behavior of a test particle is due to the negligence of the influence of the test particle to the global properties of the whole gravitating system, therefore R_H would not change during the infalling process of the test particle. Therefore a BH can indeed be formed from gravitational collapse, and “frozen stars” cannot exist in the physical universe.

(Here, R_H refers to the event horizon radius.)

 

[ctamblyn]

Yes, Farsight, it is a wild hypothesis to imagine that some parts of GR are correct except that this one particular coordinate-singularity is "real" and observer-independent. That's standard crackpot physics.

I wonder, which is the "privileged" coordinate system to use in the real world (i.e. the one that lacks spherical symmetry and may or may not be asymptotically flat, etc.)

 

[Farsight]

Did you read the paper? It quotes Oppenheimer himself agreeing with us and disagreeing with you.

Yes I did and no it doesn't, because it says this:

“An external observer [O hereafter] sees the star asymptotically shrinking to its gravitational radius [the radius of the event horizon of the BH of the same mass, RH = 2GM/c2 hereafter.].” This means that O will never witness the formation of an astrophysical BH. Given the finite age of the universe and the fact that all observers are necessarily external, the last conclusion of Ref. 1 seems to indicate that astrophysical BHs cannot be formed in the physical universe through gravitational collapse.

Yes, Farsight, it is a wild hypothesis to imagine that some parts of GR are correct except that this one particular coordinate-singularity is "real" and observer-independent. That's standard crackpot physics.

Yeah yeah, I give you the frozen star and it's some wild hypothesis? And now crackpot physics? Sheesh, come on, hurl some more abuse at me. Call me feather-spitting names, as much as you like. It only makes it even more patently obvious that you've got no counter-argument whatsoever. LOL.

 

[Farsight]

Of course it is. It disagrees with all established science, including the very same science you claim to be using to reach your conclusion.

Is that all you're left with? That the frozen star disagrees with all established science? To hell with the light and the mirrors, to hell with my post #177, you're going to ignore the scientific evidence and start bleating about all established science. Sol, I am disappointed with you. I expected rather more. I expected a rational discussion, not evasion.

I'm not choosing any coordinate system

Then you should be happy with a choice of coordinates in which the coordinate speed of light does nothing unusual at the horizon.

What part of I'm not choosing any coordinate system did you fail to understand? Coordinate systems don't exist, remember? Coordinate systems are human conventions, they have no bearing on reality. What's real is light moving through space. Or not moving through space.

But you're not, you refuse to accept that. Ergo, you're insisting on one specific coordinate system. That's precisely the contrary of the fundamental truth general relativity is based on - that choices of coordinates are meaningless and arbitrary.

I'm sorry sol, but there are no "fundamental truths", and the general relativity you've been taught is a corrupted version of the real thing. Einstein told you the speed of light varied, and the scientific evidence is right there under your nose. Get used to it.

 

[Farsight]

You're such a GR novice that you don't even notice when you're using a coordinate system.

Oh slings and arrows. I don't need a coordinate system to see two optical clocks losing synchronisation, I just look at the numbers. And I don't have to be the Brain of Britain to work out that the speed of light isn't constant, or come across Einstein telling everybody about it. Then when I hear people saying Einstein told us the speed of light is constant I can laugh and say, Ooh, lookie here, two racehorses running at the same speed:

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[Farsight]

Um, the paper you linked to disagrees with you explicitly. From pp. 5-6:

Um, I did say The author of this paper says "matter can indeed fall across the event horizon within a finite time" but disagreeing with that really isn't some wild hypothesis..

 

[ben m]

“An external observer [O hereafter] sees the star asymptotically shrinking to its gravitational radius [the radius of the event horizon of the BH of the same mass, RH = 2GM/c2 hereafter.].” This means that O will never witness the formation of an astrophysical BH. Given the finite age of the universe and the fact that all observers are necessarily external, the last conclusion of Ref. 1 seems to indicate that astrophysical BHs cannot be formed in the physical universe through gravitational collapse.

Yes, that's what we've all been saying. In the coordinate system of an external observer, objects arrive at the event horizon only when t=infinity. That's the easily-computed, well-known GR prediction for this quantity in this coordinate system. The statement that "stuff never falls in" is a statement about the experience of coordinate system O, not an invariant statement about spacetime.

And the paper explicitly points out a coordinate system, different than O, that sees stuff fall in. You have an astounding ability to ignore that.