Does matter accumulate just outside the event horizon of a black hole?

  • My understanding is that time slows and approaches stopping when approaching the event horizon of a black hole. I have seen this explained several places, including a brief explanation in the last paragraph under: http://en.wikipedia.org/wiki/Black_hole#General_relativity, quoted below:




    Oppenheimer and his co-authors interpreted the singularity at the boundary of the Schwarzschild radius as indicating that this was the boundary of a bubble in which time stopped. This is a valid point of view for external observers, but not for infalling observers. Because of this property, the collapsed stars were called "frozen stars",[17] because an outside observer would see the surface of the star frozen in time at the instant where its collapse takes it inside the Schwarzschild radius.




    Does this mean then that no matter actually falls into a black hole (except possibly what was there at its formation)? Would this also mean matter is accumulating just outside its event horizon? As I understand it, this would be the perspective from outside the black hole. If this is the case, I wonder if we would observe a tremendous amount of matter surrounding the event horizon, but it would be extremely red shifted?



    Edit:



    I noticed an answer to a different question, especially the end portion, provides some insight here as well:
    https://astronomy.stackexchange.com/a/1009/1386



    Edit:



    These YouTube videos someone put together explain the concept very well, and seem to indicate this idea is gaining traction!



    https://www.youtube.com/watch?v=yZvgeAbrjgc&list=PL57CC037B74307650&index=118
    https://www.youtube.com/watch?v=b1s7omTe1HI



    Edit:



    This new YouTube video describes this idea very well, and describes it as the way black holes work!



    https://youtu.be/mquEWFutlbs


    You should quote where you read it. However, I guess you are talking about relativistic effects (delay) observed from a distant observer. Is it correct?

    My personal opinion: That's the reason (together with Hawking radiation making the BH vanishing over finite time, as seen from outside), why an event horizon never can form. But that's not (yet?) the main-stream opinion.

    @Py-ser - Yes, this is correct, I am talking about the relativistic effects.

  • ctrebor

    ctrebor Correct answer

    6 years ago

    Yes, you are absolutely right, from OUR VIEWPOINT it does.



    From Kip Thorne's book "Black Holes and Time Warps: Einstein's Outrageous Legacy."



    “Like a rock dropped from a rooftop, the star’s surface falls downward (shrinks inward) slowly at first, then more and more rapidly. Had Newton’s laws of gravity been correct, this acceleration of the implosion would continue inexorably until the star, lacking any internal pressure, is crushed to a point at high speed. Not so according to Oppenheimer and Snyder’s relativistic formulas. Instead, as the star nears its critical circumference, its shrinkage slows to a crawl. The smaller the star gets, the more slowly it implodes, until it becomes frozen precisely at the critical circumference. No matter how long a time one waits, if one is at rest outside the star (that is, at rest in the static external reference frame) one will never be able to see the star implode through the critical circumference. That is the unequivocal message of Oppenheimer and Snyder’s formulas.”



    “Is this freezing of the implosion caused by some unexpected, general relativistic force inside the star? No, not at all, Oppenheimer and Snyder realized. Rather, it is caused by gravitational time dilation (the slowing of the flow of time) near the critical circumference. Time on the imploding star’s surface, as seen by static external observers, must flow more and more slowly, when the star approaches the critical circumference, and correspondingly everything occurring on or inside the star including its implosion must appear to go into slow motion and then gradually freeze.”



    “As peculiar as this might seem, even more peculiar was another prediction made by Oppenheimer and Snyder’s formulas: Although, as seen by static external observers, the implosion freezes at the critical circumference, it does not freeze at all as viewed by observers riding inward on the star’s surface. If the star weighs a few solar masses and begins about the size of the sun, then as observed from its own surface, it implodes to the critical circumference in about an hour’s time, and then keeps right on imploding past criticality and on in to smaller circumferences.”



    “By looking at Oppenheimer and Snyder’s formulas from the viewpoint of an observer on the star’s surface, one can deduce the details of the implosion, even after the star sinks within its critical circumference; that is one can discover that the star gets crunched to infinite density and zero volume, and one can deduce the details of the spacetime curvature at the crunch.” P217-218



    OK, so from our perspective all the matter will be clustered around the critical circumference and no further. That's fine, this shell in theory can exert all the forces required on the external universe such as gravitational attraction, magnetic field etc. The point like singularity which is in the indefinite future of the black hole, (from our point of view) indeed in the indefinite future of the universe itself could not exert such forces on this universe. This singularity is only "reached" as an observer rides in past the critical circumference and, through the process of time dilation, reaches the end of the universe.



    This is obviously an area of active research and thinking. Some of the greatest minds on the planet are approaching this issue in different ways but so far have not reached a consensus but intriguingly a consensus appears to be beginning to emerge.



    http://www.sciencealert.com/stephen-hawking-explains-how-our-existence-can-escape-a-black-hole



    Stephen Hawking said at a conference in August 2015 that he believes that "information is stored not in the interior of the black hole as one might expect, but on its boundary, the event horizon." His comment refers to the resolution of the "information paradox," a long-running physics debate in which Hawking eventually concedes that the material that falls into a black hole isn't destroyed, but rather becomes part of the black hole.



    Read more at: http://phys.org/news/2015-06-surface-black-hole-firewalland-nature.html#jCp



    In the mid-90s, American and Dutch physicists Leonard Susskind and Gerard 't Hooft also addressed the information paradox by proposing that when something gets sucked into a black hole, its information leaves behind a kind of two-dimensional holographic imprint on the event horizon, which is a sort of ‘bubble’ that contains a black hole through which everything must pass.



    What occurs at the event horizon of a black hole is very hard to understand. What is clear, and what proceeds from General Relativity, is that from the viewpoint of an external observer in this universe, any infalling matter cannot proceed past the critical circumference. Most scientists then change the viewpoint to explain how, from the viewpoint of an infalling observer, they will proceed in a very short period of time to meet the singularity at the centre of the black hole.
    This has given rise to the notion that there is a singularity at the centre of every black hole.



    However this is is an illusion, as the time it will take to reach the singularity is essentially infinite to us in the external universe.



    The fact that the matter cannot proceed past the critical circumference is perhaps not an “illusion” but very real. The matter must from OUR VIEWPOINT become a “shell” surrounding the critical circumference. It will never fall through the circumference while we remain in this universe. So to talk of a singularity inside a black hole is incorrect. It has not happened yet.



    The path through the event horizon does lead to a singularity in each case, but it is indefinitely far in the future in all cases. If we are in this universe, no singularity has yet been formed. If it has not been formed yet, where is the mass?  The mass is exerting pull on this universe, correct?  Then it must be IN this universe.  From our point of view it must be just this side of the event horizon.



    ASTONISHINGLY IT MAY BE POSSIBLE TO PROVE THIS. The recent announcement of gravitational waves detected on the merger of 2 black holes was accompanied by an unverified but potentially matching gamma ray burst from the same area of the sky. This is inexplicable from the conventional viewpoint which holds that all the matter would be compressed into a singularity and would be incapable of coming out again.



    If 2 black holes merge and emit gamma rays… the above is certainly an explanation which is also consistent with General Relativity. The mass never quite made it through the event horizon (from our viewpoint) and was perturbed by the huge violence of the merger, some escaping. It may be a deep gravitational well, but a very powerful gamma ray should just be able to escape given the right kick (attraction by an even larger black hole approaching).



    Further more refined observations of similar events, which are likely to be reasonably frequent, may provide more evidence. There is not likely to be any other credible explanation.


    Thank you for your answer, I would like to see if this generates further discussion!

    One more comment on your original question. The black hole would start like a tiny vapour bubble in the middle of the imploding star which had reached a sufficiently strong gravitational "pressure". It would then expand as surrounding matter and energy fell in and reached its critical circumference, therefore I do not think any matter from the viewpoint of an external observer would be "inside" the critical circumference.

    FYI, I am looking for proof / references to award the bounty.

    Proof/references for what? There was a considerable reference to Oppenheimer & Snyder. Do you want more?

    Actually, it appears your answer is now good as far as references go, and I may well end up awarding you the bounty. I am also looking for further proof (e.g. observations or other types of proof) that matter does or does not collect near the event horizon of a black hole. I realize such proof may not exist yet, so I will in that case reward whoever backs up their statement the best with references, etc..., and so far you have done a good job of including references.

    I will post an expanded answer then!

    This is very good, thank you for sharing! You are likely to receive the bounty unless someone can do better! Great job, and great thoughts!

    Your gravitational waves comments seem to have trouble understanding the difference between the mass and the gravitational field. Nothing about the GW detection said that mass was expelled or otherwise converted from (within) the black holes into various forms of radiation. The energy was already present in the gravitational fields, which exists within the universe and outside the event horizon. It was that energy that was converted to radiation. What's "actually" in the hole is irrelevant: what matters is the fields (gravitational and EM, namely).

License under CC-BY-SA with attribution


Content dated before 7/24/2021 11:53 AM