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I am no physics major nor math major to this but merely an amateur cosmology enthusiast, so in my previous inquiries I wasn't able to find anything on the premise that if all black holes obviously have different masses (which we know they do, as all objects do), and we know that each black hole's gravitational pull exceeds the speed of light $c$ so my question being: is it possible the escape velocities of some black holes are quite possibly much greater than $c$ itself?

Let's say if there was "super light", light that goes $10c$ (10x the speed of normal light), is it possible that the gravity of some black holes could be so extreme that it would greatly exceed even $10c$? and beyond etc. Or do black holes only "defeat" light's escape velocity by just above $c$? If I am not understand it correctly, please feel free to correct, thanks.

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    $\begingroup$ “Super light” has nothing to do with mainstream physics. $\endgroup$
    – Ghoster
    Commented Apr 14, 2023 at 18:29
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    $\begingroup$ The OP is not proposing non-mainstream physics. The "super light" hypothetical is just an attempt to understand how escape velocity near a black hole works according to standard GR. $\endgroup$
    – PM 2Ring
    Commented Apr 15, 2023 at 1:16
  • $\begingroup$ @PM2Ring We can incorporate all kinds of "magical devices" into our theories, but the only thing that comes out of that effort is intellectual nonsense. Th speed of light defines the geometry of causality in this universe. Breaking it means that causality breaks. What can a theory that behaves acausal tell us reliably about reality, which does not? $\endgroup$
    – FlatterMann
    Commented Apr 15, 2023 at 5:40
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    $\begingroup$ @FlatterMann Ok, but Deadweed1 wasn't trying to incorporate some "magical device", they just wanted to talk about speeds > c. If you don't understand how spacetime geometry works, c just seems like some arbitrary mysterious restriction. FWIW, I have some relevant info on velocity in relativity here: physics.stackexchange.com/a/291346/123208 & physics.stackexchange.com/a/598415/123208 $\endgroup$
    – PM 2Ring
    Commented Apr 15, 2023 at 7:00
  • $\begingroup$ @PM2Ring I can build a perpetual motion machine by violating any of the three laws of thermodynamics. So what, though? Neither is "just" an arbitrary "mysterious" restriction. They are defining pieces of the theoretical description of systems near thermal equilibrium. c is a direct consequence of relativity. What do I get if I give up on relativity? Certainly nothing that resembles reality. $\endgroup$
    – FlatterMann
    Commented Apr 15, 2023 at 16:18

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Escape velocity is position-dependent - the closer you are to a massive body, the faster you need to move to escape its gravitational field. We typically talk about the escape velocity at the "surface" of a body, but that's a bit of a tricky thing for a black hole.

The event horizon could be considered the "surface" of a black hole, and is the region from which light cannot escape. At positions outside the event horizon, the escape velocity is below c and light can escape. As you cross the event horizon, the escape velocity exceeds c - once it crosses the event horizon, even light cannot escape. Inside the event horizon, the escape velocity will continue to increase as you approach the singularity. By the time you are mere Planck lengths from a cosmic mass packed into a near-zero volume, the escape velocity will far exceed c.

All black holes have escape velocity equal to c at their event horizon by definition, and escape velocities much higher than c when approaching the singularity.

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  • $\begingroup$ Thank you, that made perfect sense $\endgroup$
    – Deadweed1
    Commented Apr 14, 2023 at 20:05
  • $\begingroup$ A velocity has a magnitude and a direction. The escape velocity near a black hole does not have a single magnitude for any direction, unlike in Newtonian physics. $\endgroup$
    – ProfRob
    Commented Apr 14, 2023 at 22:54
  • $\begingroup$ @ProfRob Please consider expanding that comment into an answer... $\endgroup$
    – PM 2Ring
    Commented Apr 16, 2023 at 13:07
  • $\begingroup$ @ProfRob Wouldn't that imply that light actually can escape the event horizon of a black hole, so long as it's moving in the right direction? It suggests either that some light inside the event horizon can escape, or that some light outside the event horizon cannot escape. I'm not aware of the relativistic effect you're alluding to. $\endgroup$
    – Nuclear Hoagie
    Commented Apr 17, 2023 at 13:50
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    $\begingroup$ @NuclearHoagie If you are just outside the event horizon, the only direction that light can escape is radially outwards. For all other directions it will end up "falling" back to the event horizon. As you move further away then the range of angles for which the light can escape will increase. Then for $r>3r_s/2$ light can escape in all directions that increase $r$, but not any for which $r$ decreases. This is completely un-Newtonian behaviour and is why talking about escape velocities or even escape speeds is hopeless/misleading for black holes. $\endgroup$
    – ProfRob
    Commented Apr 17, 2023 at 15:39

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