# Problem of gravitons and black holes

Discussion in 'Physics & Math' started by Ultron, Sep 28, 2016.

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http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/black_gravity.html
Purely in terms of general relativity, there is no problem here. The gravity doesn't have to get out of the black hole. General relativity is a local theory, which means that the field at a certain point in spacetime is determined entirely by things going on at places that can communicate with it at speeds less than or equal to c. If a star collapses into a black hole, the gravitational field outside the black hole may be calculated entirely from the properties of the star and its external gravitational field before it becomes a black hole. Just as the light registering late stages in my fall takes longer and longer to get out to you at a large distance, the gravitational consequences of events late in the star's collapse take longer and longer to ripple out to the world at large. In this sense the black hole is a kind of "frozen star": the gravitational field is a fossil field. The same is true of the electromagnetic field that a black hole may possess.

Often this question is phrased in terms of gravitons, the hypothetical quanta of spacetime distortion. If things like gravity correspond to the exchange of "particles" like gravitons, how can they get out of the event horizon to do their job?

Gravitons don't exist in general relativity, because GR is not a quantum theory. They might be part of a theory of quantum gravity when it is completely developed, but even then it might not be best to describe gravitational attraction as produced by virtual gravitons. See the physics FAQ on virtual particles for a discussion of this.

Nevertheless, the question in this form is still worth asking, because black holes can have static electric fields, and we know that these may be described in terms of virtual photons. So how do the virtual photons get out of the event horizon? Well, for one thing, they can come from the charged matter prior to collapse, just like classical effects. In addition, however, virtual particles aren't confined to the interiors of light cones: they can go faster than light! Consequently the event horizon, which is really just a surface that moves at the speed of light, presents no barrier.

I couldn't use these virtual photons after falling into the hole to communicate with you outside the hole; nor could I escape from the hole by somehow turning myself into virtual particles. The reason is that virtual particles don't carry any information outside the light cone. See the physics FAQ on virtual particles for details.

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https://briankoberlein.com/2015/08/21/how-does-gravity-escape-a-black-hole/

extract:
"This is how gravity can seem to act instantly while gravitational waves seem to travel at the speed of light. Gravity isn’t something that travels through space and time. Gravity is space and time."
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

Those to links for RJB, may explain it I hope!
I havn't yet perused Thorne's book, but give me time.

5. ### river

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So many books ; so little time

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And of course, the gravitational radiation from merging BH pairs, as discovered and confirmed by aLIGO, supports how gravity doesn't need to get out of a BH.
https://arxiv.org/abs/1602.03837

8. ### The GodValued Senior Member

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Make the gravity travel with BH.

#162 is good, but the problem would be motion of a BH.

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"This is how gravity can seem to act instantly while gravitational waves seem to travel at the speed of light. Gravity isn’t something that travels through space and time. Gravity is space and time."
Taking that into account, and noting how warped spacetime[gravity] seems to travel along with the mass [say Sun, and how the Earth and planets, withing that gravity/spacetime well, seem to follow it on its orbit, the whole fabricated question of how gravity gets out of a BH, and how it follows the BH wherever it goes, is just obviously a furphy.

Last edited: Oct 26, 2016
10. ### The GodValued Senior Member

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Just when the object is about to collapse below its EH, fine spacetime around it is curved. But once inside and moving, then how does the spacetime around it, which has changed due to motion with respect to a remote observer will be curved?

You can say, you don't know, no probs with that.

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Papers such as the following on one of the greatest discoveries of our time, also support and explain how and why gravity need not get out of a BH.
Clue/s being that spacetime is a continuous field, and Gravity is space and time.
https://arxiv.org/ftp/arxiv/papers/1602/1602.03837.pdf

Observation of Gravitational Waves from a Binary Black Hole Merger:

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0 × 10−21. It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410þ160 −180 Mpc corresponding to a redshift z ¼ 0.09þ0.03 −0.04 . In the source frame, the initial black hole masses are 36þ5 −4M⊙ and 29þ4 −4M⊙, and the final black hole mass is 62þ4 −4M⊙, with 3.0þ0.5 −0.5M⊙c2 radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

12. ### The GodValued Senior Member

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Popo depiction!

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I believe the whole aspect of gravity and BH's can be summed up beautifully in the following two truisms/quotes......
https://briankoberlein.com/2015/08/21/how-does-gravity-escape-a-black-hole/

extract:
"This is how gravity can seem to act instantly while gravitational waves seem to travel at the speed of light. Gravity isn’t something that travels through space and time. Gravity is space and time."

and the oft quoted John Wheeler summation......
“Spacetime tells matter how to move; matter tells spacetime how to curve.”

14. ### RJBeeryNatural PhilosopherValued Senior Member

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This is also from that link:
So gravity is space and time, but gravitational waves are still limited to a propagation velocity of c...this means that the influence of the behavior of mass behind the EH cannot reach the outside world, regardless of the word salad that's used to explain it away. The God has said the same thing: "once" the BH has formed then any change in motion "after" that point should not be possible. If it makes sense to you then congratulations.

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No explaining away necessary.
The simple fact that gravity is spacetime, and that mass warps this spacetime exhibiting the property we term as gravity, and the property of nonlinearity and the fossil field, says it all imo.

Careful, though, the god in denying just about all of 21st century cosmology, including spacetime curvature, redshift/blueshift, gravitational lensing, BH's, GR, reflects an ominous agenda.

16. ### RJBeeryNatural PhilosopherValued Senior Member

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I only continue to question when I fail to understand the provided answers. At some point I begin to wonder if others actually understand the explanations themselves.

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That's OK, I do the best i can in explaining, and realizing that sometimes certain aspects are hard for anyone to get their head around: But that's the way things are according to the data available.
Personally, I still find it hard to get my head around anything being infinite, including the universe.

18. ### The GodValued Senior Member

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Total funny and confused word salad.

Dishonest attempt. Redshift / Blueshift, gravitational lensing are observations, they are not being denied.

What is being questioned is expansion of space-time, prevalent concept of Black Hole and associated singularity, the explanation of GL based on curvature of space-time, explanation of GW as ripples in the curvature of space-time.

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The newbies and those not up with modern 21st century cosmology, need to realise that forums such as this are open to any Tom, Dick or Harry, with "tall poppy syndrome" or agendas of different persasions including religious agendas.
The latter is easily recognised in how they employ the gaps that still obviously a part of cosmology, and infer their particular brand of mystic quality on a particular part of that cosmology: 99.99% of the times they cannot explain any alternative and instead,dishonestly or subversely imply that cosmologists and physicists are just idiots and wrong, and by stealth, substitute the god of the gaps..
This was recognised in another thread in thus.....
The great Richard Feynman discusses this aspect of mystery and why here...well worth watching......

And despite any silly denial, as I said, a rejection of near all 21st century cosmology, including redshift, gravitational lensing, BH's GR, curved spacetime etc etc etc

The second point obviously is that such denials are virtualy never accompanied with any reputable citation, or reference, and as these "denialists" are also amateurs and lay people, the stupidity of such unevidenced, unsupported denials is obvious.

A third point is even more inane and shows the buffoonery of some of these characters.
Show them a refeence, link, citation, supporting the mainstream, and inevitably it is smugly written off as pop science.
Interesting definition of pop science follows......
https://en.wikipedia.org/wiki/Popular_science
"Popular science (also pop-science or popsci) is interpretation of science intended for a general audience. While science journalismfocuses on recent scientific developments, popular science is more broad-ranging. It may be written by professional science journalists or by scientists themselves. It is presented in many forms, including books, film and television documentaries, magazine articles, and web pages.

Popular science is a bridge between scientific literature as a professional medium of scientific research, and the realms of popular political and cultural discourse. The goal of the genre is often to capture the methods and accuracy of science, while making the language more accessible".

As you should be able to see, the three points apply here [1] arguing against the accepted science through incredulity, and mystery, [2]Never supporting their claims/denials, [3] and writing material given supporting the accepted version as pop science.

Gravity is space and time."
and the oft quoted John Wheeler summation......
“Spacetime tells matter how to move; matter tells spacetime how to curve.”

Last edited: Oct 27, 2016
20. ### The GodValued Senior Member

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This is what makes you look funny. How can you get denials supported by reputable citations? Reputed in the context shall be mainstream only, and if mainstream denies something, then the original is discarded and new one becomes the mainstream.

So, please do not ask for an alternative or denial to be supported by your definition of reputable citations.

And moreover people like you will not believe in denial by some scientists also. Laura Mercini was ridiculed, the new paper questioning accelerated expansion of spacetime is ridiculed. Accept that you are a hands down mindless mainstream mob part.

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http://arstechnica.com/science/2015...roversial-paper-exists-but-so-do-black-holes/

extract:
"Mersini-Houghton’s claims are even more extraordinary, however. (And we all know what extraordinary claims require.) In order to conclude that black holes don’t exist, she claims to have united general relativity with quantum mechanics, a feat which has been a sort of “holy grail” of modern physics. A unifying theory of this sort has thus far proved elusive despite the best efforts of the physics community".

22. ### RJBeeryNatural PhilosopherValued Senior Member

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Please define "exists" and you will see that it is fundamentally incompatible with black holes in GR.

I know you think you're defending or explaining modern physics from a position of authority but the fact is that I've been down this road many times with many physicists. I don't make these claims with naivete.