Philadelphia, PA

Dear Wallis,

Its seems to me that your question concerns how black holes could radiate. You ask:

Black holes can't emit light waves, likewise they can't emit gravity waves and cannot exert gravitational force on matter outside. So how do the proponents explain two black holes pulling on each other, orbiting in the gradually closing binary system?

---end quotation

The key to the production of gravitational waves is not that massive objects emit gravity waves, but that the acceleration of massive objects does. Black holes, since they constitute massive objects, do curve space-time in their vicinity, however, and other objects follow the lines of curvature. In the LIGO discovery, it is the mutual acceleration of two black holes toward each other, and the consequent loss of angular momentum which is responsible for the emission of gravitational waves.

The oscillation of a charge produces electromagnetic radiation, and  the concept of gravitational radiation is analogous: accelerating masses emit gravitational radiation, though in most cases, and with small masses, this is negligible. Its takes the acceleration of gigantic masses to produce detectable gravitational radiation.

The hypothesis of gravitons does not really belong to the standard model of particle physics --which does not include gravity. Instead it belongs to proposals to extend the standard model to include gravitation. These proposals are much more speculative than the standard model. While gravitational waves were strongly and confidently predicted as a large-scale implication of Einstein's theory of general relativity, the concept of the graviton, as the supposed carrier of the gravitational force, is much more problematic, since this concerns extremely small scale phenomena, at or near the Planck length, and falls into the domain of proposals for theories of quantum gravity. Gravitational waves are an implication of GR, gravitons not.

In any case, if one follows the proposals for gravitons (Freeman Dyson, e.g., has expressed strong doubts that they could ever be detected), then they would arise as the quantum of the gravitational field in correspondence with gravitational waves. It is not that black holes, un-accelerated, or other massive bodies would be though to emit gravitons, instead, like the gravitational waves, they would be emitted by accelerating masses.

The two black holes are supposed to "pull on" each other, simply by following the curved space-time in their mutual vicinity. This is in accord with GR. But as they approach each other and there is a loss of angular momentum, the local curvature is repeatedly perturbed so as to produce the expanding gravitational radiation.

H.G. Callaway

The link explains the possible underlying mechanism:

http://phys.org/news/2016-02-ligo-twin-black-holes-born.html

@Wallis: "Black holes can't emit light waves, likewise they can't emit gravity waves and cannot exert gravitational force on matter outside"

Black holes can of course exert gravitational force on matter outside. For that they need not emit gravitational waves.  Black holes have gravitational attraction which at a distance is more or less the same as that of a larger gravitating body of the same mass. They can also have an electric field, but that is probably rare, because postitive and negative charges tend to cancel each other. However, in principle, a charged black hole is possible and its static electric field has no problem getting outside.

Regarding gravitational waves, these can be emitted by a black hole, when it is dynamic, such as, for example, in the case of two black holes circling around each other. Gravitation will deform their horizons periodically and in trying to restore its spherical or ellipsoidal shape, each horizon oscillates and then emits gravitational waves. A single spherical black hole without spin will not emit gravitational waves, a black-hole binary does. (A single spinnig black hole also emits gravitational waves but to a much smaller extent.)

It seems to be hard to explain how nothing is pulling any object but the matter is pulling the space for to be space-supported matter ie as slow energy concentrate, a local package. The gravity is the flow of vacuum energy supporting inertial bodies not to be only space-like phenomena but having delayed time-like causal mechanism to exist. All bodies move due to that flow accelerating apparently in respect of each others, because bodies need space support balanced in all directions. The gravity is fictitious force.

Gravity is an isotropic force and also has an instant impact. So impact of the gravity does not have a structure of propagating wave. Therefore it is not possible to say that we expect the gravitational force of any object will effect us at a certain time.

The gravitational waves from a binary black hole coalescence are generated outside the black hole horizons. In numerical simulations regions that lie inside the horizons are usually excised. This approach is referred to as black hole excision. (See, for instance, the book: "Numerical Relativity" by T.W. Baumgarte and S.L. Shapiro, Cambridge Univ. 2010).

Good Question

Truth is,  what this experiment elegantly shows is that gravitational ripples in space time are governed by the speed of light, but the gravitons themselves must be tachyonic in this instance, i.e the ones that emerge from the black hole event horizon are going faster than light .

Otherwise  logically the  gravity of a black hole could not exert itself. 

There are other examples of things going faster than light. Inflation itself being a generally accepted instance

How else can gravity extending out of a black hole be explained?

Max, how indeed!

Suppose for a moment that matter can penetrate an event horizon. Let's have a shell of particles falling in to a large BH, reaching the event horizon in proper time t1 and the central singularity in proper time t2. For the external universe, a long time elapses between t1 and t2. OK, that interval is not finite and the whole arrangement is naive but let's not quibble just yet. We can make the separation between the infalling particles arbitrarily large - so large that they are very unlikely to interact with one another. In this scenario several problems emerge. Firstly, the BH entropy is supposed to shoot up, despite the lack of particle interactions. Secondly, information associated with the infalling shell is lost. Thirdly, any electrical charges possessed by the infalling particles vanish from the universe because their virtual photon mediated electric fields cannot fight the superluminal tide in order to escape. Fourthly, both theory and observation suggests that gravity cannot propagate faster than light, so matter trapped within an event horizon can exert no gravitational influence on the external universe. These patently absurd implications are all a consequence of the mistaken assumption that particles can penetrate an event horizon in a universe of finite age - and the amnesia surrounding Einstein's 1939 dismissal of black holes as unphysical for this very reason.

Andrew Worsley: How else can gravity extending out of a black hole be explained?

The space flow into the massive concentration, no information need to come out if the gravitating body is a smooth sphere like a black hole is.

Btw, still I don't see black holes possible because of QM for example.

Esa - I think you may have confused 'QM is currently unable to describe black holes' with 'QM does not allow the possibility of black holes'. The maths is just the description, not the reality - remember that you cannot prove a negative.

The math is just a description. That's true.

I haven't confused anything. To falsify the theory is the way...

In summary so far, I see most responders stay within general relativity.  Robin Spivey says “matter trapped within an event horizon can exert no gravitational influence on the external universe”. Andrew Worsley agrees we would need faster-than-light tachyons to connect the black hole to normal space.  Norbert Straumann, says model calculations excise the black holes inside the event horizon.   The waves are generated in inspiralling matter outside the event horizon and the masses of the two black holes (29 and 36 solar masses) given by the LIGO team refer to masses outside the event horizon.  Robin Spivey reminds us that Einstein (1939) rejected black holes because no particles penetrate an event horizon in finite time. It seems that despite LIGO claiming the first direct detection of black holes, they would be of arbitrary mass and still remain hidden inside the individual and combined event horizons. 

There’s the issue of what we mean by mass in GR.  The gravitational mass is lower than the total matter, by the energy of the gravity field (in mass terms) – there’s a significant mass defect in GR objects, analogous to the mass defect/binding energy in atomic nuclei [PIRT15 Marshall-Wallis 2015].  Does this perhaps extend in ’black holes’ to mass defects equating to their total matter-mass, leaving them with no external gravitational mass?

Dear Max Wallis

In your summary I have to correct one thing you wrote about my previous comment. The waves are not generated by inspirally matter, but by the changing vacuum solution, which describes originally two separated black holes (Kerr solutions) in orbital motion. The beautiful thing about black hole coalescence is that this is a pure vacuum problem for Einstein's Equations. No matter enters, so the problem is parameter-free, up to the masses (and spins) of the two black holes. These are then obtained by comparing the theoretical wave forms with the observations. (By the way, a combination of the two masses, the so-called chirp mass, can be obtained quite accurately by using only the lowest approximation in a post-Newtonian expansion and the observed evolution of the frequencies. This is now treated in text books on gravitational waves.)

What is perhaps the most interesting aspect of the discovery is that we see for the fist time the working of Einstein's vacuum equations for strong fields and very rapid time changes. Because of the extreme nonlinearities of these equations, the problem could only be handled theoretically thanks to important progress in numerical relativity,

I feel that the LIGO collaboration could have been more thorough in their analysis and less biased in their interpretation of the data, especially as they had many hundreds of authors and took several months to report the discovery of gravitational waves. To me, two rather prominent features in the signals seem to confirm that the objects commonly referred to as black holes do not in fact possess event horizons but are instead stabilised by the time dilation predicted within general relativity, which can grow arbitrarily strong. Future detections of gravitational waves should be able to confirm or refute whether a small but significant fraction of the coalescing matter is routinely ejected during the most violent phase of 'black hole' coalescence. I need hardly remind anyone that black holes are not supposed to be capable of rapidly shedding their contents, even in the most extreme of circumstances.

Article Coincident Down-chirps in GW150914 Betray the Absence of Eve...

I think the work on gravitational waves is still on its early stages and its too early to say what's really happened there to generate such a massive gravitational waves could be something else, how knows?

I think we need to add more of remote systems to at least give a certain assumption about the direction from which these waves has been emitted. Then using other techniques of observations we can then know what are really there to emit these waves.

Dear Esa Säkkingen

The question, how the gravitational field of a collapsed body can escape if there is no information passing from inside the horizon to the exterior, is an old one. Technically, this has been shown by Oppenheimer and Snyder in 1939. In a non-technical language the answer  (given for instance in popular talks by Penrose in the 1960s) is:

The gravitational field does not escape, but corresponds to that of the body before the collapse. This can not suddenly be switched off, because this would require information after the star disappeared behind the horizon, and this is just not possible. Therefore the field -- for example -- of a spherically symmetric black hole is the same as the one of a spherically symmetric star outside its surface (the Schwarzschild field).

There is nothing mysterious about that.

In this connection: The reason why Einstein wrote in 1939 (shortly before Oppenheimer and Snyder) a paper against the existence of black holes is rather strange. The mathematics of his considerations is correct (and by the way also very simple), but they prove nothing against black holes. He really missed the point. This is clearly explained in detail in Kip Thorn's beautiful popular book.

The gravitational field isn't the reason of the problems with black holes. If the event horizon was perfect smooth, there would be no need for signals from the horizon out. But how could horizon get that kind of smoothness? I can see only that the whole black hole should be an elementary particle like electron, muon, tau, tau-1, tau-2,... whatever and there is difficulties with remain charges when collapsing and so on.

Hence, I prefer thinking other possibilities to discussing on black holes. For example, I'm interested in some scale-change solution, "miniaturation", if there were such at heavy gravity. It means no event horizons but inflation-like transitions in spacetime geometry.

Robert Spivey's paper is interesting- that details of the 'Chirp' in the gravitational pulse imply mass ejection.  And says the black-hole binary would have no inspiralling matter discs while mass ejection from black holes is impossible.  His exclusion of neutron stars as the explanation is however wrong, as our solutions for neutron stars as shells of matter held out by huge interior gravitational field do not have a limiting size.  Certainly they can be 20 times bigger than the TOV limit of 2.0Msun given for neutron stars with matter-filled interiors.

On a second point, the Oppenheimer-Snyder-Penrose argument against escaping G-field led people (Einstein included) to believe that gravitational waves are not real.  The discovery of the Hulse-Taylor pulsar binary spinning down did prove that energy is being lost - so was the first indirect proof of gravitational waves and disproof of the OSP argument.  The basic modelling of G-wave detectors should therefore be based on material displacements by the wave pulse, rather than contraction of the metric locally.  The LIGO observation showed the energy pulse is highly localised in space (and time), not non-localised as Thorne and collaborators used to theorise (based on formulations of GR with a pseudo-energytensor rather than newer formulations with a real energytensor - Fock, Weinberg and others).

Norbert Straumann's concept that the G-wave comes from a changing vacuum solution irrespective of matter (my apologies for assuming he had coronas of matter outside event horizons) does not satisfy a mass-energy balance central to Hilbert and Einstein's original GR.

Just one comment to the last claim of Max Wallis: This statement is plain wrong. In binary black hole coalescence total energy conservation is maintained, as for any isolated system with an asymptotically flat space-time. The only general bound for the released energy follows from the second law of black hole dynamics, that shows that a lot of energy can be released as gravitational radiation (see, for instance my textbook on GR, Sect.8.6.8 ). The actual amount in the LIGO discovery can be reasonably well approximated with a simple first order calculation, as presented for instance in the book by Michele Maggiore, Sect. 4.1.

There are other wrong statements in his reaction, but I leave it with that.

The reality is that the closer we come to our galaxy and our solar system, the less issues we see "solved" by GR. Only for very distant events that are only partially measurable, there is "evidence" found for GR.

Why? Because the "evidences" are fabricated by making fit the maths to the partial information that is available, and the theories, such as that of black holes, are adapted to make it fit.

However, in reality, the close-by events like the Gravity Probe B results, the Lunar Laser Ranging results, the asteroids' motion and the velocity curve of galaxies can only be explained by Heaviside's gravitomagnetism.

Thierry

What about the binary pulsar (nor very far from us in the Milky Way)? Another example: Since, as a result of various satellite missions and other reasons (for instance Pulsar Timing), we now know the planet masses much more accurately, and -- together with powerful computers --, the anomalous perihelion motion (deviation from Newtonian theory) is now known to much higher precision. GR predicts this value to three decimal places an incredible triumph of the theory (see a recent review by Cliff Will). Can you obtain this value??

Norbert

The reality is that there is absolutely nothing to be proud of GR. See the anexed link to a paper that explains the poor status of GR.

I obtain the value of the anomalous perihelion motion with Oliver Heaviside's gravitomagnetism (1983) by including the motion of the Sun in the Milky Way. This substantiates the effect physically.

Your "incredible triumph" is based upon a calculus of the Newtonian part by Le Verrier, which has proven errors. Le Verrier took the half major axis as the average orbit radius, which is wrong in terms of the average velocity, needed for relativity issues. Instead, he should have taken a(1+e^2/2) (see wikipedia). The error is 10 arcsec/century for Mercury, which strongly affects the 43 arcsec/century.

But guys like you will make the figures fit to three decimal places at all cost, since it gives value to your job...

Neither the Post Newton equations proves the anomalous perihelion motion intrinsically, nor does the so-called perturbation theory, the hijacked gravitomagnetism, which needs flattened planets, another fraud...

So, no linearized GR theory proves it, unless by chosing some appropriate parameters. This also clarifies the futility of your claim "Can you obtain this value??". If it were that important, how can you possibly use linearized theories to support GR for other issues, while they don't prove Mercury's issue intrinsically?

http://vixra.org/abs/1603.0127

Very quick answer: The numbers I indicated are not using Le Verrier, but N-body simulations with powerful computers and far improved observational data. History is interesting, but completely irrelevant for the current situation. I find your remarks indeed very strange.

Philadelphia, PA

Dear Wallis,

Its seems to me that your question concerns how black holes could radiate. You ask:

Black holes can't emit light waves, likewise they can't emit gravity waves and cannot exert gravitational force on matter outside. So how do the proponents explain two black holes pulling on each other, orbiting in the gradually closing binary system?

---end quotation

The key to the production of gravitational waves is not that massive objects emit gravity waves, but that the acceleration of massive objects does. Black holes, since they constitute massive objects, do curve space-time in their vicinity, however, and other objects follow the lines of curvature. In the LIGO discovery, it is the mutual acceleration of two black holes toward each other, and the consequent loss of angular momentum which is responsible for the emission of gravitational waves.

The oscillation of a charge produces electromagnetic radiation, and  the concept of gravitational radiation is analogous: accelerating masses emit gravitational radiation, though in most cases, and with small masses, this is negligible. Its takes the acceleration of gigantic masses to produce detectable gravitational radiation.

The hypothesis of gravitons does not really belong to the standard model of particle physics --which does not include gravity. Instead it belongs to proposals to extend the standard model to include gravitation. These proposals are much more speculative than the standard model. While gravitational waves were strongly and confidently predicted as a large-scale implication of Einstein's theory of general relativity, the concept of the graviton, as the supposed carrier of the gravitational force, is much more problematic, since this concerns extremely small scale phenomena, at or near the Planck length, and falls into the domain of proposals for theories of quantum gravity. Gravitational waves are an implication of GR, gravitons not.

In any case, if one follows the proposals for gravitons (Freeman Dyson, e.g., has expressed strong doubts that they could ever be detected), then they would arise as the quantum of the gravitational field in correspondence with gravitational waves. It is not that black holes, un-accelerated, or other massive bodies would be though to emit gravitons, instead, like the gravitational waves, they would be emitted by accelerating masses.

The two black holes are supposed to "pull on" each other, simply by following the curved space-time in their mutual vicinity. This is in accord with GR. But as they approach each other and there is a loss of angular momentum, the local curvature is repeatedly perturbed so as to produce the expanding gravitational radiation.

H.G. Callaway

Norbert

What makes it different? Even Einstein found that the perihelion advances of the other planets, calculated by GR, are wrong!

Thierry

Times have changed. You seem to be completely ignorant about that.

Norbert

Yes, times have changed. Now you fabricate the solutions and make them suit your fantasies by using the approprate parameters and the appropriate calculus, like the authors of the binary star decay calculus admitted.

However, no close-by cosmic phenomenon has been solved by GR. Neither the velocity curves of the galaxies, nor the gravitational description of Saturn's rings and the nodes in the external rings, nor the motion of asteroids in the asteroid's belt, nor the flatness of the Milky Way, nor the Lunar Laser Ranging or the Gravity Probe B results. Moreover, you can not explain non-exploding fast spinning stars, the shape of SN1987a, and so on!

Only Heaviside's gravitomagnetism can get these results, and it has been confirmed!

But by hijacking gravitomagnetism, morfed by using supposedly flattened spheres, and only deduced by trickery from GR, you fabricate the right results, knowing well that you need gravitomagnetism.

But then, you don't get the perihelion advances either intrinsically!

So, the only way is to perform a curve fit as you do in PN, with the adapted masses of the planets as it suits you, since only a fraction of deviation of the masses, oblateness, and the orbits is necessary to "prove" your issues.

The proofs are clear: an Indian paper, based upon "personal communications"!!

Article Relativistic Perihelion Precession of Orbits of Venus and the Earth