This question already has an answer here:

Edit: I don't think this is a duplicate. [***]

Question: Based on our current observations, what prevents a black from experiencing any sort of repulsive force to overcome its gravitational force and ultimately become not a black hole? [**]

Clarifications to the question

By "current observations" I mean theories/equations that have observation to back them up, and aren't hypothetical.

By "black hole" I am not referring to micro black holes.

My own attempt to answer the question

Since there are (4) fundamental forces[*], let's look at each as potential candidate:

Gravity is what holds a black hole together and is attractive, so unless there is "anti-gravity"[*] gravity will not be responsible for apart a black hole.

The strong nuclear force has never been observed on large distances (I think) so I don't know how it could affect a black hole.

The weak nuclear force seems like a candidate, based on my understanding. The decay we've observed appears random, so it's possible for the matter within a black hole to decay. By being random over enough time has an expected value of having "lucky spurts" of weak force over large enough time may play a part in tearing apart a black hole. Given a chance of $0.0 < p < 1.0$ of something happening (such as a "lucky spurt" of weak decay) within some time duration $t$, for some observer, it has a $1-p$ chance of not happening within $t$. Since $0.0<1-p<1.0$, $(1-p)^n<0.5$ for some integer $n>0$, which means if you wait $n*t$ durations for a "lucky spurt" of weak decay to happen you have a lower chance of it not happening than it happening, so it will "probably" happen. (Any "lucky spurt" of decays that has the highest probability to happen would probably be just a small amount of mass reduction and would be more likely to happen than "hyper-lucky spurt" decay ejecting a large amount of mass, so this decay would happen very gradually, but maybe have an occasional burst, most likely, and now this sounds like it would be related to Hawking radiation which I think can shrink a black hole gradually, but I don't know much about it, although a search for the text "weak" on its Wikipedia page didn't show anything mention of the weak force as its culprit.)

The electric force seems like a candidate, as well, based on my understanding. What's stopping a black hole from accepting new charged particles unless the increase of repulsive electric force from charge is somehow nullified by a corresponding increase in gravity by the mass carrying the charge (assuming charge implies a mass carrying that charge) or somehow the black hole can repulse additional charge from entering its event horizon in the first place. I found a few questions on this site relating to black holes from gaining arbitrarily high electric charge ("Charging a black hole?", "What prevents the accumulation of charge in a black hole?") but their answers were either dense that I couldn't understand it in a short amount of time or seemed slightly implausible (i.e. Why isn't Coulomb repulsion overcome by sufficiently high velocity at the optimal direction?).

Therefore, a good answer to this question would explain why weak and electric forces are not good candidate forces to tear apart a black hole based on observation (and confirm my understanding about gravity and strong force to not be candidates, either). (Links that provide the answer are okay, of course.)


[*] While I'm completely open-minded to the existence of additional fundamental forces and/or anti-gravity when/if it is observed, it has not been observed, so it doesn't meet the criteria of my question.

[**] If you think any part of this question can be improved, you're probably right - feel free to do it, particularly if you think the spirit of my question is still captured and it makes this question no less a fit for the content of this site. I don't know much physics and I know even less about what is appropriate to assume the answerer's (and future readers) will know and err on the side of verbose.

[***] Though I can't see for sure, I'm guessing people are voting to close this question because of this one: "Are black holes really singularities?".

That question is asking about seems to be asking if some repulsive force prevents black holes from being able to form in the first place. The answers are about answering whether or not black holes can form in the first place. That is a different question than mine, which is assuming black holes are able to form, in accordance to our observations, are they able to un-form. All (3) of the answers support my interpretation of the other question:

...there is always a case where gravity can overcome the strongest repulsive forces. That is why physicists believe it must collapse into a black hole.

Another (downvoted) answer says this:

[Like OP predicts,] Black holes do not have singularities. Since all matter of a black hole is located in its spherical shell, the internal spacetime is flat.... if some matter was inside the spherical shell, there would be information loss paradox.

And another says this:

It's not an assumption [that black holes collapse into a singularity], it's a calculation plus a theorem, the Penrose singularity theorem.

To those who add a close vote after reading this: can you comment to me why my question is considered a duplicate/why my interpretation given above is wrong so I can better learn the rules of this community and submit appropriate content?


marked as duplicate by DilithiumMatrix, CuriousOne, Gert, Prahar, Sebastian Riese May 5 '16 at 18:59

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • 3
    $\begingroup$ Possible duplicate of Are black holes really singularities? $\endgroup$ – DilithiumMatrix Apr 20 '16 at 3:59
  • $\begingroup$ @DilithiumMatrix Thank you for the comment. Please see my edit if you get a chance. Thank you. $\endgroup$ – Words Like Jared Apr 20 '16 at 4:27
  • 1
    $\begingroup$ Comment to the title (v3): What does the phrase "a formed black" in the title mean? $\endgroup$ – Qmechanic Apr 20 '16 at 9:30
  • $\begingroup$ @Qmechanic it was to emphasize that my question is different from this one which is asking whether or not black holes actually form. $\endgroup$ – Words Like Jared Apr 20 '16 at 13:09

Once you are inside the event horizon every form of energy just increases the gravity. For example when discussing the weak force you suggest:

By being random over enough time has an expected value of having "lucky spurts" of weak force over large enough time may play a part in tearing apart a black hole.

by which I assume you're thinking of a decay in which mass energy is converted into kinetic energy of the decay products. The problem is that the fast moving decay products gravitate just like the original mass did so this cannot eliminate the event horizon. The same applies to decays mediated by the strong force. This happens because the source of the spacetime curvature is not just mass, but rather an object called the stress-energy tensor. This includes contributions from the momentum and pressure of matter/energy as well as from its mass.

The one case where one of the four forces can affect the large scale geometry is the electromagnetic force, but the reason this happens is a bit different to the mechanisms you suggest. A charged black hole is described by the Reissner-Nordström metric, and this has some significant differences from the uncharged Schwarzschild metric. In principle (though not in practice) if you can increase the charge enough the event horizon will disappear to leave a naked singularity.

However the reason this happens is that the electromagnetic force is a long range force so electrostatic field created by the charge exists both inside and outside the event horizon. Speaking rather loosely, the part of the field inside the horizon pulls the event horizon inwards but the part of the field outside the horizon pulls the horizon outwards. If you make the charge great enough the outside pull wins and the horizon disappears.

I should add an important caveat to this. The Reissner-Nordström metric, like the Schwarzschild metric, is an idealised description and the black hole it describes is time independent meaning it has existed forever and will continue to exist forever. It would not be a good description of a process involving adding charge to an existing black hole. The hypothetical experiment of adding charge to an existing black hole would be described by some variant of the Oppenheimer-Snyder metric, and I'm not aware of any studies of this process.

For completeness I should also add that there are excellent reasons to believe the charge could never be increased enough to create a naked singularity.


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