I'm assuming that when particles come in contact with the event horizon, they start traveling directly to the singularity, which is one point that might need clarification. Tangent particles would obviously act this way, but particles entering at wide angles might "whirlpool" down into the singularity.

My question only applies to the first case, which when crossing the event horizon, the quarks would not be able to move when the strong force acts upon them. Additionally, even the gluons themselves would have to travel toward the singularity. All quarks would instantly travel in straight lines to the singularity, which seems to indicate that matter just disintigrates into subatomic particles at the event horizon. Is this correct?

  • $\begingroup$ There are no free quarks in space, they will cross the event horizon within hadrons and will keep that way. up to the singularity. $\endgroup$ – anna v Sep 12 '19 at 18:44
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    $\begingroup$ A particle that that crosses the event horizon at a certain point in spacetime then has a future light cone with its vertex at that point. It can have any timelike trajectory within that light cone. $\endgroup$ – Ben Crowell Sep 12 '19 at 19:26
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    $\begingroup$ @annav Do you agree that hadrons get spaghettified by gravitational tidal force? $\endgroup$ – G. Smith Sep 12 '19 at 19:58
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    $\begingroup$ @StephenG I don’t agree. There are accepted approaches to QFT in curved spacetime. Birrell and Davies wrote a book on it. QCD in curved spacetime is not that conceptually different from EM in curved spacetime, and we certainly think we know how to write Maxwell’s equations in curved spacetime. Unless you care about what is happening within, say, a Planck length of the singularity, you don’t need quantum gravity to answer this. $\endgroup$ – G. Smith Sep 12 '19 at 21:09
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    $\begingroup$ @G.Smith Incidentally I'm not sure we can even describe what a "singularity" is in the context of such small sizes and high energies. The singularity is a concept not really described by existing QFT/GR theories at this level of detail. I'm dubious we can make the assumption of a "pure" singularity existing. $\endgroup$ – StephenG Sep 12 '19 at 21:57

There are no free quarks in space, they will cross the event horizon still within the hadrons and will keep that way up to the singularity.

Here is, as an example, what a proton really is in terms of quarks:

enter image description here

Whether the tidal force a proton encounters at the singularity is strong enough to turn it into a quark gluon plasma phase depends on the model of quantized gravity used. At present there is no definitive quantization of gravity, only effective theories.

Here are the forces a particle feels at the event horizon:


As you see the smaller the mass of the black hole ( small horizon radius) the higher the force, but certainly it is not enough to rip a hadron apart. What happens after the capture is a matter of the model used.

  • $\begingroup$ Does this mean that particles crossing the event horizon a few degrees above tangent would do a whirlpool while falling into the singularity? $\endgroup$ – snowg Sep 13 '19 at 4:53
  • $\begingroup$ It depends on the model used to do calculations, on the assumptions about initial values ..... $\endgroup$ – anna v Sep 13 '19 at 5:29

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