A brief history of black holes

I read Sabine Hossenfelder’s latest blog post yesterday. The title was A brief history of black holes. I left a couple of comments. One was a reply to Louis Marmet, and referred to Oppenheimer’s 1939 frozen star black hole. I said I think the black hole grows like a hailstone, from the inside out. The other was addressed to Hossenfelder, and referred to Einstein talking about the variable speed of light. I said that IMHO this had to mean Penrose/Hawking singularity theorems were wrong. I found that neither comment appeared. Hence I thought I’d spend a little time going through the blog post giving my thoughts. I’m black, with blue hyperlinks. Hossenfelder is green:

The possibility that gravity can become so strong that it traps light appears already in Newtonian gravity, but black holes were not really discussed by scientists until it turned out that they are a consequence of Einstein’s theory of general relativity.

This is wrong from the off. Einstein made it crystal clear that a gravitational field is a place where the speed of light is spatially variable. Have a read of this Wikipedia article:

Like physicsFAQ editor Don Koks says, “light speeds up as it ascends from floor to ceiling”. In a strong gravitational field, it speeds up all the more, so strong gravity doesn’t trap light. That’s not to say black holes don’t exist. But they don’t exist because gravity is strong. They exist because they’re a place where the “coordinate” speed of light is zero. Note though that Einstein talked of the speed of light, not the coordinate speed of light. Light doesn’t behave like a ball that slows on the way up and goes faster on the way down. By the by, the local speed of light is not always c. A stopped observer doesn’t see light moving at c. He sees nothing. Ever. Zero divided by zero is not one.

General Relativity is a set of equations for the curvature of space and time, called Einstein’s field equations. And black holes are one of the possible solutions to Einstein’s equations. This was first realized by Karl Schwarzschild in 1916. For this reason, black holes are also sometimes called the “Schwarzschild solution”.

This is also wrong. General Relativity is a theory of gravity, not a set of equations for the curvature of spacetime. Curved spacetime is a curvature of the “metric”. Gravity is real, but the metric is an abstract thing, associated with measurement. Think of it as a curvature in your plot of your measurements of space and time. Imagine you could place a 15 x 15 array of optical clocks throughout a horizontal slice of space around the Earth. Then you plot all the clock rates, such that the lower slower clock rates generate data points lower down in a 3D image, and the higher faster clock rates generate data points higher up in the 3D image. When you join the dots, your plot looks like this:

CCASA image by Johnstone, see Wikipedia

That’s your typical Riemann curvature tensor image, the “rubber-sheet” depiction of curved spacetime. But it’s derived from optical clock rates, so what it’s really plotting is the variable speed of light. It isn’t plotting curved space and curved time. That’s why Einstein said a gravitational field is a place where space is “neither homogeneous nor isotropic”. Not a place where space is curved.

Schwarzschild of course was not actually looking for black holes. He was just trying to understand what Einstein’s theory would say about the curvature of space-time outside an object that is to good precision spherically symmetric, like, say, our sun or planet earth. Now, outside these objects, there is approximately no matter, which is good, because in this case the equations become particularly simple and Schwarzschild was able to solve them.

Hooray. The curvature of spacetime. Not the curvature of space and the curvature of time. A gravitational field is a place where space is “neither homogeneous nor isotropic”. Not a place where space is curved.

What happens in Schwarzschild’s solution is the following. As I said, this solution only describes the outside of some distribution of matter. But you can ask then, what happens on the surface of that distribution of matter if you compress the matter more and more, that is, you keep the mass fixed but shrink the radius. Well, it turns out that there is a certain radius, at which light can no longer escape from the surface of the object, and also not from any location inside this surface. This dividing surface is what we now call the black hole horizon. It’s a sphere whose radius is now called the Schwarzschild radius.

There’s nothing wrong with that. Apart from the explanation for why the light can’t escape. It’s because the speed of light at the event horizon is zero. So the vertical light beam doesn’t ascend from the event horizon. And remember this: the speed of light can’t go lower than zero. That’s important. Light can’t go slower than stopped.

Where the black hole horizon is, depends on the mass of the object, so every mass has its own Schwarzschild radius, and if you could compress the mass to below that radius, it would keep collapsing to a point and you’d make a black hole.

Who says it would keep collapsing to a point? It wasn’t Einstein. It wasn’t Oppenheimer either. It was Penrose and Hawking. Two guys who were doing their own thing, and had clearly never read what Einstein said.

But for most stellar objects, their actual radius is much larger than the Schwarzschild radius, so they do not have a horizon, because inside of the matter one has to use a different solution to Einstein’s equations. The Schwarzschild radius of the sun, for example, is a few miles*, whereas the actual radius of the sun is some hundred-thousand miles. The Schwarzschild radius of planet Earth is merely a few millimeters.

No problem. The Schwarzschild radius of the Sun is circa 1.9 miles, and the Schwarzschild radius of the Earth is circa 9 millimetres.

Now, it turns out that in Schwarzschild’s original solution, there is a quantity that goes to infinity as you approach the horizon. For this reason, physicists originally thought that the Schwarzschild solution makes no physical sense. However, it turns out that there is nothing physically wrong with that. If you look at any quantity that you can actually measure as you approach a black hole, none of them becomes infinitely large. In particular, the curvature just goes with the inverse of the square of the mass. I explained this in an earlier video. And so, physicists concluded, this infinity at the black hole horizon is a mathematical artifact and, indeed, it can be easily removed.

It can only be “easily removed” by using tortoise coordinates. That’s seconds of infinite length, which is total crap. You cannot get rid of infinite gravitational time dilation by introducing smoke-and-mirror seconds of infinite length. Not unless you’re a mathematical quack peddling total garbage.

With that clarified, physicists accepted that there is nothing mathematically wrong with black holes, but then they argued that black holes would not occur in nature because there is no way to make them. The idea was that, since the Schwarzschild solution is perfectly spherically symmetric, the conditions that are necessary to make a black hole would just never happen.

That’s what Einstein said in his 1939 paper on a stationary system with spherical symmetry consisting of many gravitating masses. For some reason he missed the significance of Oppenheimer and Snyder’s 1939 frozen star paper on continued gravitational contraction. Maybe it was because war was looming, and he had other things on his mind. I don’t know. But I do know he should have predicted gamma ray bursters. Because falling bodies don’t slow down. And because those falling bodies are falling because the speed of light is reducing. He missed the trick. Maybe that was his greatest blunder. The irony is that the detection of gamma ray bursters reawakened interest in general relativity in the 1960s. In fact, that’s why Hawking proposed his Hawking radiation. See his 1974 Nature paper on black hole explosions?

But this too turned out to be wrong. Indeed, it was proved by Stephen Hawking and Roger Penrose in the 1960s that the very opposite is the case. Black holes are what you generally get in Einstein’s theory if you have a sufficient amount of matter that just collapses because it cannot build up sufficient pressure. And so, if a star runs out of nuclear fuel and has no new way to create pressure, a black hole will be the outcome. In contrast to what physicists thought previously, black holes are hard to avoid, not hard to make.

This is incorrect in that Penrose and Hawking proved nothing, because they did their own thing and ignored Einstein. But it is correct in that black holes are what you get if a big star runs out of fuel. The issue of course is this: is there a point singularity in the middle of a black hole? The answer has to be no, because light can’t go slower than stopped. At the event horizon there is no more gradient in the speed of light, so no gravitational field. So now you know why all that stuff about an elephant in two places at once is absolute nonsense:

Image from the New Scientist article the elephant and the event horizon

The bottom line is this: if there’s a paradox, there’s something wrong somewhere. Probably something seriously wrong, right at the beginning.

So this was the situation in the 1970s. Black holes had turned from mathematically wrong, to mathematically correct* but non-physical, to a real possibility. But there was at the time no way to actually observe a black hole. That’s because back then the main mode of astrophysical observation was using light. And black holes are defined by the very property that they do not emit light.

There’s some rewriting of history here. See the 1971 Physics Today article introducing the black hole by Remo Ruffini and John Wheeler who said “in this sense the system is a frozen star”. This sort of thing is par for the course in contemporary physics. When you’ve read the old papers, you realise how bad it is.

However, there are other ways of observing black holes. Most importantly, black holes influence the motion of stars in their vicinity, and the other stars are observable. From this one can infer the mass of the object that the stars orbit around and one can put a limit on the radius.

No problem with that. That’s what Sagittarius A* is all about. See the animations produced by Andrea Ghez and team at the UCLA Galactic Center Group using Keck datasets:

Animation by Andrea Ghez and research team at UCLA

There’s something there with a mass that’s circa 4.28 million times the mass of the Sun. But it’s at most thirty times bigger than the Sun in terms of spatial extent. There’s only one thing it can be, and that’s a black hole. Hence we’re confident that black holes exist. As to their exact nature, that’s another story.

Black holes also swallow material in their vicinity, and from the way that they swallow it, one can tell that the object has no hard surface.

You can’t tell what’s inside the black hole from observations of infalling bodies. However you can surely say something about gamma ray bursts. See the 2013 AMPS paper an apologia for firewalls. Tucked away in the conclusion is footnote 31, containing a reference 87 to Friedwardt Winterberg’s 2001 paper gamma ray bursters and Lorentzian relativity. Winterberg talked about the direct conversion of an entire stellar rest mass into gamma ray energy“if the balance of forces holding together elementary particles is destroyed near the event horizon, all matter would be converted into zero rest mass particles which could explain the large energy release of gamma ray bursters”I’m sure Winterberg is essentially correct. Unfortunately he gets no publicity. He gets “studiously ignored” instead whilst people like Hossenfelder pretend to be the expert and suck up to Penrose.

The first convincing observations that our own galaxy contains a black hole came in the late 1990s. About ten years later, there were so many observations that could only be explained by the existence of black holes that today basically no one who understands the science doubts black holes exist.

Again, no problem with that, but see Peter Erwin’s comment about Cygnus X-1. The issue is the nature of black holes. I say they’re frozen stars, others say they’re point singularities. I say point singularities contradict Einstein’s general relativity.

What makes this story interesting to me is how essential it was that Penrose and Hawking understood the mathematics of Einstein’s theory and could formally prove that black holes should exist. It was only because of this that black holes were taken seriously at all. Without that, maybe we’d never have looked for them to begin with. A friend of mine thinks that Penrose deserves a Nobel Prize for his contribution to the discovery of black holes. And I think that’s right.

I don’t. I think Penrose did his own thing and appealed to Einstein’s authority whilst flatly contradicting the guy. That was his MO. See MTW, which refers to Eddington-Finkelstein coordinates. Box 31.2 on page 828 says Eddington and Finkelstein used free-falling photons as the foundation of their coordinate system. Only those photons aren’t falling faster and faster, they descend slower and slower. Also see the Wikipedia article, which says this: “they are named for Arthur Stanley Eddington and David Finkelstein, even though neither ever wrote down these coordinates or the metric in these coordinates. Roger Penrose seems to have been the first to write down the null form but credits it (wrongly) to the above paper by Finkelstein, and, in his Adams Prize essay later that year, to Eddington and Finkelstein”. Penrose was making it up as he went along. Yea verily. If that isn’t enough, have you ever sat down and taken a long hard look at Penrose diagrams which plot the route to the parallel antiverse?

Penrose diagram from the CERN courier article Physics in the multiverse, image credit Andrew Hamilton

FFS. The parallel antiverse. The word that springs to is charlatan. As for Hawking, see his singularities and the geometry of spacetime dating from 1966. On page 76 he talked of “such a strong gravitational field that even the ‘outgoing’ light rays from it are dragged back”. It’s clear Hawking didn’t understand the first thing about gravity, and had never read what Einstein said. He was winging it, and getting an easy ride on account of the wheelchair.

* Unfortunately, a mistake in the spoken text.

No problem. But what is a problem, is so-called physicists like Hossenfelder peddling horseshit on the internet and censoring those who refer to bona-fide papers and point out the issues. This sort of thing is endemic. There isn’t just something rotten in the state of QED. There’s something rotten in the state of physics. Safe spaces and no-platforming is how these guys have been operating for fifty years. It truly is the trouble with physics.

 

PS: If all this is new to you, you might want to take a look at this:

The speed of light is not constant
How gravity works
The principle of equivalence and other myths
Black holes
Hawking radiation
The Hawking papers
The information paradox
Firewall!

This Post Has 20 Comments

  1. Greg R. Leslie

    I’ve noticed a curious pattern with Dr. Hossenfelder in her videos. Several years ago she dressed as a plain jane and came across as strictly academic. She often collaborated with her colleague friends.
    Then her personal appearance became much more glamorous, the videos are now slickly produced,the videos were all about her expertise, and she even began to do singing presentations!(PUKE!) My take is it’s now all about celebrity first, truth distant second. £-$-£ to infinity and beyond.

    1. I think you’re spot on there, Greg. Yes, it’s celebrity first, and truth a distant second. For myself I don’t mind Sabine Hossenfelder’s videos, or the singing. I don’t like them, but that’s up to her. It’s her choice. What I do dislike is the way she censors factual informative comments that point out issues with what she’s saying. Peter Woit is the same. Ditto for Matt Strassler, Luboš Motl, and others. This sort of thing seems to be endemic with academics. It seems like propaganda and censorship is their way of life. It seems like they’re all self-appointed experts engaged in self-promotion, who have a massive intellectual arrogance, and who brook no challenge. Even when they’re peddling abject nonsense.

  2. Sabine Hossenfelder said this on her blog: Several people have tried to submit comments to this thread which contain links to websites I don’t recognize. I want to remind you all that I don’t approve links except those to journals, the arXiv, or well-known newspapers. When in doubt, please consult the comment rules.
    .
    So let’s try this:
    .
    Louis: I think it’s straightforward myself, because I think Oppenheimer and Snyder’s original “frozen star” black hole is correct. See On Continued Gravitational Contraction dating from 1939. It was no flash in the pan – see the 1971 Physics Today article Introducing the black hole by Remo Ruffini and John Wheeler. They said “in this sense the system is a frozen star”. There is no central point singularity. But there is a black hole. It grows from the inside out, like a hailstone. Imagine you’re a water molecule. You alight upon the surface of the hailstone. You can’t pass through this surface, but soon you’re surrounded by other water molecules, and eventually you’re buried by more. So whilst you can’t pass through the surface, the surface can pass through you. I can’t explain why Einstein missed this in his 1939 paper On a stationary system with spherical symmetry consisting of many gravitating masses. Or the prediction of gamma ray bursters. Perhaps it was because war was looming and his mind was elsewhere.
    .
    Of course, Einstein’s “spatially variable” speed of light must mean Penrose/Hawking singularity theorems are wrong. That’s because in a gravitational field the ascending light beam speeds up. In a strong gravitational field, the ascending light beam speeds up even more. It doesn’t get dragged back, like Hawking said on page 76 of his 1966 paper Singularities and the geometry of spacetime. See Is The Speed of Light Everywhere the Same? by PhysicsFAQ editor for something contemporary on this.

  3. Greg R. Leslie

    Hopefully John, she will let your newest comments in. Better yet she actually acknowledges her mistakes, but unfortunately I doubt it.
    Here’s a couple of new b.s. articles that made me giggle. 1.) On the New Scientists site a claim at hints of possible new forces to add to the Standard Model. It also claims that gravity still can’t be explained! Of course I would have to subscribe to be enlightened on what the new 4th,5th,or even 6th levels of quantum energies might possibly be . Poor me, I guess I shall intentionally remain an ignoramus by not subscribing. Talk about bollocks in the form of clickbait. 2.) On SciTechDaily, the exiting newest life changing discovery is Higg’s Spectroscopy! Brought to us by the esteemed physicists at HZDR & MPI-FKF ! What a bunch of happy horseshit! What’s next, Higg’s Colonoscopies?
    I am seriously thinkin about leaving the trucking & logistics industry to become a Celebrity Quantum Physicist, I’ve been told for years I have a genuine talent for blowing smoke up other people’s arses…………….

    1. Oh LOL! I am rolling around laughing here. Yep, the science media is full of horsesh*t. They have a symbiotic relationship with physicists peddling woo. As to why, well, New Scientist said when they put the word quantum on the cover, sales go up. What are they saying now? I see the article. It’s the usual Goebbelesque nonsense. Hence I’m no longer a subscriber. Mind, you, this was good in SciTech Daily: Russian Astrophysicists Trace Neutrinos – Mysterious “Ghost Particles” – From Where No One Had Expected. I expected neutrinos from gamma ray bursts. See http://physicsdetective.com/firewall/.
      .
      Yep, that latest comment of mine appeared on Backreaction. There’s a new post now, so a brief of history of black holes is history.

  4. Greg R. Leslie

    Neutrinos possibly being expelled out from the lowest end of the electromagnetic spectrum? Very intriguing indeed. The next question I would ask : does it have to occur during a massive,cataclysmic event, or at any transmission of radio waves? Do the neutrinos occur in any other spectrum emissions, or even thru all spectrums? Not just cataclysmic gamma bursts you and others have written about. We need to pay continuing attention to these fine folks in Russia.

  5. The neutrinos aren’t being expelled from the electromagnetic spectrum, Greg. It would be something like a forced beta decay. If you were falling into a black hole, your neutrons would disintegrate first. Then your electrons. Then your protons. There would be transient pions etc, but you would end up as a bunch of photons and neutrinos departing in different directions at the local speed of light. The same would happen to much of the matter of a collapsing star. Think of each particle as a disintegrating flywheel. Angular momentum is conserved because the parts fly off in those different directions. The parts would fly off in different directions for an electron as opposed to a positron.

  6. Greg R. Leslie

    Thanks for the clarification John ! After a carefull reread I think know were I went wrong? I conflated the act of emergence of the neutrinos at the same time as the radio waves,with the production source of neutrinos (forced beta decay) ,with the production source of photon based radio waves? Two completely different particles and processes .
    I do want to be accurate with my statements, even if it does make my cerebral neurons scream in agony from even remedial usage………..

  7. Unanimous

    So if mass turns into gamma ray bursts on falling into a black hole, what makes a black hole increase in mass like a hailstone? Does some of the gamma ray energy enter the black hole and increaes its mass? Does other massless radiation passing by hit the black hole and turn into mass on its surface -eg. radiation frozen onto the surface of the black hole?

    1. Yes, IMHO some of the gamma rays or neutrinos add to the black hole. Radiation is “frozen onto the surface”, as it were. Then more radiation comes along, and the original radiation ends up below the surface, as per the hailstone analogy. The same applies to matter at the center of a collapsing star. In my view there’s not much difference between radiation and matter. Radiation is akin to a pressure pulse in space propagating linearly through space at c, which reduces in line with gravitational potential. Matter is radiation in a closed path. I don’t know if you’ve read http://physicsdetective.com/what-energy-is/, but at the fundamental level, I see space and energy as the same thing. So the interior of a black hole is akin to dense frozen space in which there is no motion.

      1. Unanimous

        But the black hole moves through space?
        Edit: Okay, just saw comments below.

  8. Eric

    Your favored theory of the frozen star black whole should make some significant and testable predictions, no? I think once it’s figured out how an object with a local surface speed of light of zero can move through space, and you rectify the paradoxical event horizon radii dependant on reference frame, you should find momentum will interact with the other parameters of a black whole, rather than momentum being an independent parameter.

    Also, just curious, have you read Thomas Kuhn’s Structure Of Scientific Revolutions? It very cogently discusses why paradigms in science, once adopted aren’t questioned until some specific conditions are usually met, all as matter of efficiency.

    It seems the current paradigm in quantum physics is a bit of a cargo cult science. Paradigm emergence in science seems to follow a pattern of increasing disagreement around the old paradigm, followed by a coalescence of agreement around the new paradigm. Quantum physics has never had a real consensus; with the dozens of interpretations and ontologies in disagreement from the very beginning. The appearance of consensus is constantly emphasized in every class you could take on the subject. It’s pounded into knew students if science constantly that QM is the best theory we’ve ever had and to question it means you don’t understand it, but no one really understands it, so don’t be surprised that it doesn’t seem quite right.

    I think the two places where from a new paradigm will emerge are particle physics and quantum optics. Particle physics follows an absurdly bad model with dozens of invented free parameters to get the Standard Model to agree with experiment. But it is also an incredibly profitable field, that’s had success getting billions of dollars from government funding, and because of that, it’s not likely anytime soon to admit their paradigm is wrong.

    Quantum optics on the other hand uses very cheap apparatuses and conducts experiments that are close to probing the fundamental nature of mass, stress energy properties of the vacuum, and variance in c.

    1. Hi Eric. There’s some good points in your comment.
      .
      As for significant and testable predictions for the frozen star black, try this: black holes don’t fall down. There’s no dynamical motion inside the black hole like there is inside an electron. So the mechanism by which a body falls down just isn’t there. However I don’t see an issue with the black hole moving through space. An iceberg moves through the sea, even though the water in the iceberg is frozen.
      .
      As for the paradoxical event horizon radii dependant on reference frame, I think that’s based on a misconception. The event horizon is where light is stopped, and that’s that. A stopped observer does not see a stopped clock ticking normally. Zero divided by zero is not one. The Schwarzschild singularity is not merely some abstract artifact of some abstract coordinate system. It’s real.
      .
      Yes, I’ve read Thomas Kuhn’s Structure Of Scientific Revolutions. I think his point is broadly correct, but I don’t know if it’s quite appropriate to the current situation. So many paradigms are set in stone by Nobel prizes and monumental vested interest. I’d say that’s why the current paradigm in quantum physics is now cargo cult science. It isn’t going to be easy to fix. Like you said, particle physicists are not likely any time soon to admit that their paradigm is wrong. Yes, quantum optics sounds more promising. I’ve noticed work by Aephraim Steinberg et al and by Jeff Lundeen et al. I don’t know if they count as quantum optics guys, but I think they’re on the right lines. I wish people like that got more publicity. And other people too. I know bona-fide professional physicists who cannot get their papers into high-impact journals, and who struggle to obtain media attention. The situation is not good. Meanwhile physics is withering on the vine. Which is why people like me try to do their bit I suppose.

  9. Greg R. Leslie

    Hey John, as far as the subject of media attention goes, I have two mostly lame thoughts: 1.) Have you or your like minded colleagues who can’t get published ever thought about going in the opposite media direction and start a Face Book or You Tube page(s) ? I know it’s not very professional or overly academic, but do you think stooping that low would help? At least it is exposure. 2.) After watching Dr.Sabine’s latest YouTube post about “Is faster than the speed of light possible?”, she definitely has mastered the art of exposure. That cheeky little minx!

    1. I have, Greg. There are some great YouTube guys out there, like Destin Sandlin from Smarter Every Day. I was looking at video cameras a while back. But I’ve been busier recently with work work, and haven’t done anything about it. I don’t have an issue with YouTube physics being “not very professional or overly academic” etc. It’s just another medium, and I would like to counter some of the really lame lies-to-children garbage we see from the likes of Don Lincoln. I just don’t have enough free time at the moment.

      1. Greg R. Leslie

        Cool, I look forward to that day. And if you do decide to become a You Tuber, I will gladly contribute a meager monetary amount if you go the patronage route.

  10. Donald Tipon

    I have read several of your articles and I believe you are correct but I still have some questions.
    1. I believe the energy-stress tensor is ultimately about electromagnetic wave densities. Are you saying that the higher the density of electromagnetic waves the slower the speed of light waves? How does this density slow the speed of light?
    2. At the surface of a black hole and below its surface you say the motion of light is zero. I would think if light stopped all motion it would no longer be an electromagnetic wave and would cease to exist. Poof! What is your concept? Is it possible that light slows but never gets to zero?
    3. As light slows does the dimension of space shrink? Is a black hole a hollow empty shell?

    1. Are you saying that the higher the density of electromagnetic waves the slower the speed of light waves? Not quite. I’m saying the higher the energy-density of space, the slower the speed of light waves. Of course, if you pushed a zillion photons into a small location, you will achieve this.
      .
      At the surface of a black hole and below its surface you say the motion of light is zero. I would think if light stopped all motion it would no longer be an electromagnetic wave and would cease to exist. Poof! What is your concept? My view is that it still exists as a region of space where the spatial energy-density is higher than usual. I view the photon as a pressure-pulse of space propagating through space.
      .
      Is it possible that light slows but never gets to zero? I don’t think so. Because black holes are black. The upward light beam doesn’t get out.
      .
      As light slows does the dimension of space shrink? Is a black hole a hollow empty shell? I don’t think so. I think it’s more like “solid space”. I view space and energy as the same thing. If you haven’t already, take a look at this article: http://physicsdetective.com/what-energy-is/

  11. Donald Tipon

    Thanks for the answers. I have a continuing question.
    1. I see your point that all types of energy density will add to the slowing of light. So you say a black hole is composed of very highly stressed spaces. I have difficulty understanding the stress-energy-momentum tensor matrix but I think that in a black hole all the momentum vectors are zero and only pressure is left to be measured as energy. Even if there are other stresses that I don’t know about, how do non-moving highly stressed spaces attract other non-moving highly stressed spaces and create what we call gravity to hold a black hole together? What prevents the black hole from exploding?

    1. Donald: I view space as something like a gin-clear ghostly elastic medium. See Robert Close’s 2009 elastic space paper:
      .
      https://link.springer.com/article/10.1007/s00006-010-0249-1
      .
      Light propagates through space like any other wave propagates through an elastic medium. Hence Maxwell’s expression for the speed of light V =√(m/ρ), where “m is the coefficient of transverse elasticity, and ρ is the density”. For the wave to propagate, space must have the properties of both stress and tension. That tension is in essence the strong force. It keeps a proton together, but you can annihilate a proton with an antiproton to yield gamma photons. That strong force tension doesn’t then disappear, it keeps the photon together, and it keeps it propagating at the speed of light. That tension is still there even when V (=c) is zero and space is unyielding. That’s what keeps the stress, which is a directional pressure, contained. Or at least I think it does. Maybe 13.8 billion years ago, it didn’t.
      .
      PS: I also think of a gravitational field as a stress or pressure gradient in space. But please note that I do find it rather difficult to ascribe qualities like stress and pressure and tension and energy density or just density to space. You can’t define it in terms of other things. IMHO space isn’t made of things. Things are made of space.

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