Wormhole tunneling to escape black holes?

[Yora]

You can't come back from crossing the event horizon of a black hole because you would have to go faster than the speed of light.

But a wormhole is a theoretical solution that allows you to travel faster than the speed of light without moving at a higher speed.

So if you had a space ship that could travel through space by opening wormholes as desired, could you use that to get out of a black hole again? After all, there is nothing special about the space inside the event horizon, other than that the speed to get out is greater than the speed of light. The really funky space warping weirdness is happebing in the singularity at the center of the black hole. As long as you jump through your wormhole before falling into the singularity, I don't see a reason why it shouldn't be possible. At least theoretically.

[Douglas]

As soon as your wormhole opens, the black hole's gravity starts going through it. As one end of the wormhole is already inside the black hole's event horizon, the gravity there is strong enough to form an event horizon around the other end of the wormhole too, and the gravity pulling you away from the remote end of the wormhole is just as insurmountably strong as the gravity preventing you from leaving the normal way.

I think.

Kind of hard to be certain about exotic phenomena that require technology that might as well be magic by our current understanding.

[Lord Torath]

Assuming you have a big-enough black hole that you're not pulled apart by tidal forces before crossing the event horizon? And that you've found an inactive one, that's not currently surrounded by a kajillion-degree cloud of gas? I would still tend to say, no you can't. But I really don't know enough to be able to answer that question with any degree of accuracy.

[halfeye]

Since the singularity of a rotating black hole is a ring, I wonder why it isn't possible to have one rotating energetically enough that the event horizon is a torus?

[Yora]

The singularity is not a ring. It's a point with a diameter of zero.

Though I think the actual definition is "a region of infinite density". Could such a region have an area?

As soon as your wormhole opens, the black hole's gravity starts going through it. As one end of the wormhole is already inside the black hole's event horizon, the gravity there is strong enough to form an event horizon around the other end of the wormhole too, and the gravity pulling you away from the remote end of the wormhole is just as insurmountably strong as the gravity preventing you from leaving the normal way.

I think.

Good point. If you place the wormhole between your ship and the singularity, you could enter the wormhole. But gravity probably wouldn't alow you to exit it on the other side. You just exit it on the same location in space where you entered it and then continue your path towards the singularity.

I think.

[halfeye]

The singularity is not a ring. It's a point with a diameter of zero.

Though I think the actual definition is "a region of infinite density". Could such a region have an area?

This second exterior is sometimes thought of as another universe. On the other hand, in the Kerr solution, the singularity is a ring, and the curve may pass through the center of this ring. The region beyond permits closed time-like curves.

My bold. I don't claim to understand any of it, but the english there seems conclusive to me, unless I'm reading it wrong, which is entirely possible.

https://en.wikipedia.org/wiki/Kerr_m...s_as_wormholes

Which is a subheading of:

https://en.wikipedia.org/wiki/Kerr_metric

[Douglas]

My bold. I don't claim to understand any of it, but the english there seems conclusive to me, unless I'm reading it wrong, which is entirely possible.

https://en.wikipedia.org/wiki/Kerr_m...s_as_wormholes

Which is a subheading of:

https://en.wikipedia.org/wiki/Kerr_metric

That's talking about a particular special kind of black hole, though. Yora's hypothetical is about a standard black hole.

[Dodom]

I'm no astrophysist so don't take this as word of god, but in my understanding, escape velocity is the speed you need not to fall back. Throw something outwards, it moves away while losing speed as gravity pulls it back in (the whole inertia VS potential energy thing). Throw something faster than escape velocity, and distance decreases gravity's effect faster than it can be slowed.
That means something can't escape a black hole's horizon because it'd never have enough speed not to fall right back, but is there anything stopping something from escaping at a slower speed if it has continuous thrust? (Aside from the practical issues such as getting destroyed before you can attempt anything and never having enough fuel to actually do it; I'm talking hypotheticals.) The same way rockets never move anywhere near Earth's surface escape velocity.

[halfeye]

That's talking about a particular special kind of black hole, though. Yora's hypothetical is about a standard black hole.

Well yeah, the special kind that's rotating. Which is going to be almost all of them. The sun is rotating. I would guess most stars are rotating, any mass falling into a black hole will probably come in at an angle. Net result, 99.99 % of black holes will be rotating.

[factotum]

That means something can't escape a black hole's horizon because it'd never have enough speed not to fall right back, but is there anything stopping something from escaping at a slower speed if it has continuous thrust?

That's not really relevant when you're talking about light. Light can *only* travel at lightspeed, yet it can't escape from inside the event horizon of a black hole. If light can't escape, nothing else can, no matter how much thrust it has.

[warty goblin]

I'm no astrophysist so don't take this as word of god, but in my understanding, escape velocity is the speed you need not to fall back. Throw something outwards, it moves away while losing speed as gravity pulls it back in (the whole inertia VS potential energy thing). Throw something faster than escape velocity, and distance decreases gravity's effect faster than it can be slowed.
That means something can't escape a black hole's horizon because it'd never have enough speed not to fall right back, but is there anything stopping something from escaping at a slower speed if it has continuous thrust? (Aside from the practical issues such as getting destroyed before you can attempt anything and never having enough fuel to actually do it; I'm talking hypotheticals.) The same way rockets never move anywhere near Earth's surface escape velocity.

Escape velocity is the minimum velocity you'd need to fire a projectile away from a massive body so that the projectile never falls back to the original body. It's a handy number because the escape velocity is proportional to the kinetic energy you need to give to the projectile (k = .5*m^v^2). So if you know your projectile's mass, the escape velocity of a given body tells you how much energy you need (at minimum) to launch your projectile. Notably it does not tell you that you ever need to go that fast; no human-built spacecraft launched from Earth even comes close to Earth's escape velocity. But they all use (substantially more than) the minimum energy implied by the that velocity.

Which is why you can't rocket your way out of a black hole's event horizon. You'd need enough energy to accelerate your rocket to above light speed. It requires infinite energy to accelerate a massive body to light speed, and the universe only contains a finite amount of mass/energy. So once you fall past the event horizon, there's literally not enough stuff in the universe to get you back out again.

[HandofShadows]

Isn't thins all assuming you can create a wormhole that close to a black hole and even if you did would it connect to space outside the black hole? When you get to a black hole physics as we know them tend to go out the window.

[GreyBlack]

You can't come back from crossing the event horizon of a black hole because you would have to go faster than the speed of light.

But a wormhole is a theoretical solution that allows you to travel faster than the speed of light without moving at a higher speed.

So if you had a space ship that could travel through space by opening wormholes as desired, could you use that to get out of a black hole again? After all, there is nothing special about the space inside the event horizon, other than that the speed to get out is greater than the speed of light. The really funky space warping weirdness is happebing in the singularity at the center of the black hole. As long as you jump through your wormhole before falling into the singularity, I don't see a reason why it shouldn't be possible. At least theoretically.

Depends. Are you able to survive the crushing gravity well that is a black hole?

[Douglas]

Depends. Are you able to survive the crushing gravity well that is a black hole?

If the black hole is big enough you don't feel any particular strain even inside its event horizon. You just get accelerated, whole, faster than any force could possibly resist. The gravity itself only gets dangerous when you're close enough to the center for the difference in gravity between nearby points to be noticeable.

[Yora]

When you get to a black hole physics as we know them tend to go out the window.

Physics inside the singularity make no sense under the equations we currently have. The region between the event horizon and the singularity is still "normal space". We just can't see into it, but all the normal laws apply. (The numbers you have to enter into the equations become extreme, as will be the results, but the math is the same as in regular space outside of black holes.

And there's always this freaky detail that a hypothetical black hole with a mass equal to all mass in the observable universe would have a diameter that is equal to the diameter of the observable universe.
But I've seen people claim that that's coincidence and doesn't mean anything...

[georgie_leech]

And there's always this freaky detail that a hypothetical black hole with a mass equal to all mass in the observable universe would have a diameter that is equal to the diameter of the observable universe.
But I've seen people claim that that's coincidence and doesn't mean anything...

It's more fair to say that if it does mean something, we don't know what that could be. At the moment, it's of no real significance, so it mostly gets relegated to the "Neat Coincidence" pile.

[Misery Esquire]

And there's always this freaky detail that a hypothetical black hole with a mass equal to all mass in the observable universe would have a diameter that is equal to the diameter of the observable universe.
But I've seen people claim that that's coincidence and doesn't mean anything...

Because if it meant we were in a black hole, everything would be being drawn in but currently it (seems to be, and/or is believed to be) moving outward, and everything is disc-shaped rather than a sort of egg-shape that you would expect if it were being pulled on. Plus, we'd have no light most of the time because it would be yoinked away from us when we're opposite the singularity from the sun, and would be a massive trail in the sky when we're not directly in the path. I think? I'm not actually an astrophysicist ; take my pondering with a hefty block of salt.

And if it was the singularity that was universe sized, we'd not have... Anything. Assumedly? I don't actually know this part ; "singularity size" is a question I've been meaning to look into. I guess it could be that the Universe Black Hole's singularity is our universe, and it is eating other universes of matter to provide us with more stuff.

(We should claim the name Universe Prime before any of those other multiverses think of it.)

But then, where is it coming out? Maybe, akin to galaxies, universes have interior clusters that you wouldn't be able to see out of very well, and we're in the cluster which is much hotter than the outside, and we just can't tell that the... Universal Nursery is in here with us?

Or is it more of an accretion disk, and the reason everything seems to be moving outward is because, like the dirt around a drain, it is building up further and further out. Then, because you need more stuff to create the outer ring of a disc, we get drawn toward that edge, while the edge continues to get further away because there are new outer rings being added.

(It is probably all just a coincidence, and I'm talking crazy talk for fun.)

[Dodom]

Which is why you can't rocket your way out of a black hole's event horizon. You'd need enough energy to accelerate your rocket to above light speed. It requires infinite energy to accelerate a massive body to light speed, and the universe only contains a finite amount of mass/energy. So once you fall past the event horizon, there's literally not enough stuff in the universe to get you back out again.

That would mean the step in potential energy between a point immediately in and out of the event horizon to be infinite, which would work both ways, something going in would immediately need to shed infinite energy, and I'm pretty sure we'd hear about that.

[Fable Wright]

And there's always this freaky detail that a hypothetical black hole with a mass equal to all mass in the observable universe would have a diameter that is equal to the diameter of the observable universe.
But I've seen people claim that that's coincidence and doesn't mean anything...

I'm no astrophysicist, but I think that would imply that we're in the event horizon of the black hole whose singularity is the center of the observable universe. We can't escape further because black hole. And it's expanding. A hypothetical wormhole jump outside of the observable universe would therefore be the same question as that which you're posing here. Maybe has something to do with dark matter/energy/flow. Probably has already been considered and dismissed, though.

EDIT: Also makes sense with that whole 'big bang' thing. That was just an unfathomably huge star going supernova, singularity at its core, giant cloud of gas getting sucked in, making one big ol' new universe that's refining itself into smaller stars. We're even less cosmologically significant than we think!

[factotum]

That would mean the step in potential energy between a point immediately in and out of the event horizon to be infinite, which would work both ways, something going in would immediately need to shed infinite energy, and I'm pretty sure we'd hear about that.

Even if that's true (which I don't think it is), nothing can escape from a black hole, so no, we wouldn't hear about that.

[halfeye]

Even if that's true (which I don't think it is), nothing can escape from a black hole, so no, we wouldn't hear about that.

I'm not sure that's correct. We don't have an efficient safe space drive yet, and maybe we will never make or find one, and whether we do or not black holes will probably always be dangerous.

However:

The event horizon of a black hole is spherical. As the black hole gets more massive, the event horizon expands. This means, that the radius of curvature of the event horizon increases with some positive function of the mass. Light cornering around the event horizon is being bent less sharply at the event horizon of a big black hole than a small one. The bigger a black hole gets, the less the gravitational force there is at the event horizon. There ought to be a very huge size of black hole, probably bigger than we've yet detected, where the inward force at the event horizon was one Earth gravity or less.

[georgie_leech]

The event horizon of a black hole is spherical. As the black hole gets more massive, the event horizon expands. This means, that the radius of curvature of the event horizon increases with some positive function of the mass. Light cornering around the event horizon is being bent less sharply at the event horizon of a big black hole than a small one. The bigger a black hole gets, the less the gravitational force there is at the event horizon. There ought to be a very huge size of black hole, probably bigger than we've yet detected, where the inward force at the event horizon was one Earth gravity or less.

That's... really not how Black Holes work. The event horizon has the same gravitational strength regardless of size, since it's defined as the point where spacetime is curved enough that light cannot escape from the gravity well. More massive Black Holes could have gentler horizons where the difference in gravity between the side of an object nearer the Black Hole and the side further isn't enough to immediately rip it apart, but that doesn't change how impossible it is to escape. Whether you die quickly or not, once you cross the event horizon, there's no escape.

[halfeye]

That's... really not how Black Holes work. The event horizon has the same gravitational strength regardless of size, since it's defined as the point where spacetime is curved enough that light cannot escape from the gravity well.

Also defined as the theoretical surface immediately below the distance from the singularity at which light would orbit the hole continuously.

As that surface becomes bigger, the curve on a unit length of it becomes less.

Light that is being bent less by the black hole is obviously under less gravitational attraction from it.

I do understand that these things are in theory dangerous to get near, and I don't expect to do that.

However, some people seem to be saying that they defy physics, and that's not right either.

[Douglas]

Also defined as the theoretical surface immediately below the distance from the singularity at which light would orbit the hole continuously.

Actually, the point where light would orbit a black hole is outside the event horizon, by 50% of the event horizon's radius if I recall correctly. Inside that orbit, light will spiral inwards at an increasingly steep gradient.

At the event horizon, even light that is going directly away from the black hole, rather than tangential to it, cannot escape.

[halfeye]

Actually, the point where light would orbit a black hole is outside the event horizon, by 50% of the event horizon's radius if I recall correctly. Inside that orbit, light will spiral inwards at an increasingly steep gradient.

At the event horizon, even light that is going directly away from the black hole, rather than tangential to it, cannot escape.

Ooh, that's interesting, sounds like something I'd seen elsewhere but didn't understand.

Do you also disagree with my belief that the gravity at the event horizon become less as the black hole becomes more massive and the event horizon becomes bigger?

[Red Fel]

My understanding of wormholes is that, functionally, they permit two separate points in space to occupy the same point in space, simultaneously. It's not a tunnel, where you enter one end and emerge the other, but a place where you are here and there at the same time.

If you are occupying both ends of the wormhole simultaneously, then anything acting on one end is necessarily acting on the other. If your wormhole opens into the ocean, there is water on both sides. If it opens into a roaring blaze, there is fire on both sides. And if one end opens into a singularity, then the force exerted by said singularity is exerted on both ends of the wormhole. This is true even if one end of the wormhole is outside of the event horizon; because the other end is within its gravitational pull, both ends feel the effect of its gravity.

This is, of course, assuming that my understanding is an accurate one.

[Rakaydos]

Because if it meant we were in a black hole, everything would be being drawn in but currently it (seems to be, and/or is believed to be) moving outward, and everything is disc-shaped rather than a sort of egg-shape that you would expect if it were being pulled on. Plus, we'd have no light most of the time because it would be yoinked away from us when we're opposite the singularity from the sun, and would be a massive trail in the sky when we're not directly in the path. I think? I'm not actually an astrophysicist ; take my pondering with a hefty block of salt.

Try this on for size- it's a 4d black hole, and the "direction" toward the center of the universe-blackhole is time. you can move freely in any on the other directions, but you must move at effectively the speed of light through time. (c, the speed of light, being the ratio of space to time)

[georgie_leech]

Ooh, that's interesting, sounds like something I'd seen elsewhere but didn't understand.

Do you also disagree with my belief that the gravity at the event horizon become less as the black hole becomes more massive and the event horizon becomes bigger?

If you shone a light outwards just within the event horizon, the light would not escape. It doesn't matter how big the event horizon is, that's the entire point.

[halfeye]

If you shone a light outwards just within the event horizon, the light would not escape. It doesn't matter how big the event horizon is, that's the entire point.

It is one point. There are a whole bunch of points about black holes.

[georgie_leech]

It is one point. There are a whole bunch of points about black holes.

The entire point of the event horizon, I mean. If the force of gravity was weaker, light could escape, so that point isn't behind the event horizon.If you quadruple the mass of a black hole the event horizon is twice as far away, but not weaker.