The picture we have of black holes is that within the event horizon there are no paths through spacetime leading out again. But of course that’s with the caveat of being restricted to the speed of light. If it really is possible for a warp drive to move a spaceship faster than light, could it escape from the interior of a black hole?
ETA: an even more bizarre question is, if it could exactly when would it reappear in the outer universe? Time does some strange things when black holes get involved.
Any answer would depend on exactly how the FTL drive violated our current understanding of physics. Sadly, without the details (and any we have right now would be fiction) an answer is not possible.
In sci-fi warp drive is scrunching up space in front of you so the distance from A → B is less.
In theory you are not traveling at FTL speeds. You are shortening the distances from you to your destination. Think taking a tablecloth and bunching up the cloth in front of you so less distance to travel.
Closest I have seen to a serious proposal is the Alcubierre drive. But that needs negative matter which no one has ever seen. Fairy dust. But, if you can find some of that fairy dust then there is reason to think it can be done.
Can you escape a black hole with it…I can’t even guess at that.
As I understand it, we already know exactly how it works. It is a well defined mathematical formulation called the Alcubierre drive: Alcubierre drive - Wikipedia
The formulation does require negative mass or ridiculous levels of energy but the question should be answerable, as I understand it. Happy for one of our residents to tell me I am wrong though.
Well, I really would like the Alcubierre drive to be a practical idea, but it if absolutely isn’t with our current technology. So I would say we really don’t know what a FTL drive would actually look like or what its limitations are, and we have no idea what its capabilities might be. We only have proposals of how one might work, and no guarantee that’s what the OP means.
I am not precisely familiar with the latest models of warp drives, but black holes are kind of similar: you just need to specify the mass and angular momentum (and electric charge).
They are not synonymous, unless you are possibly thinking that almost every type of “warp drive” mentioned was/is an “Alcubierre Drive”. The “Alcubierre Drive” is a possibility, but it not the only possibility unless the OP clarifies what they mean by the term.
Pretty sure negative mass is needed and there is the problem. From your own cite:
The Alcubierre drive ([alkuˈβjere]) is a speculative warp drive idea according to which a spacecraft could achieve apparent faster-than-light travel by contracting space in front of it and expanding space behind it, under the assumption that a configurable energy-density field lower than that of a vacuum (that is, negative mass) could be created.
AFAIK negative mass has never, ever, been seen. Maybe it exists on paper but we’ve never found it.
Well, we know that space can expand at a speed faster than light.
and we know that nothing travelling at light speed or below can escape a black hole.
so if a warp drive uses faster-than-light expansion of space, it should be able to escape. If not, not.
The engineering problems associated with making a warp drive are another matter.
My preferred method for escaping a black hole is via a wormhole. If you can multiply-connect two distinct regions of space with a wormhole they stay connected so long as the wormhole persists; it doesn’t matter if one of those locations is inside a black hole, in another universe or even in the distant past or future.
Here is a story by the great Geoffrey Landis describing a black hole/wormhole combo, with fascinating repercussions.
The term “warp drive” was used in Star Trek in 1965 and in other fiction as early as the 1930s. That usage was many decades before the Alcubierre drive was first proposed in 1994, so the terms cannot be synonymous.
I would assume the question is really just “if you can travel faster than light, could you escape after you’d entered the event horizon of a black hole?” Otherwise they’d need to specify the exact type of warp drive they mean.
Not locally. Space isn’t expanding against the “grid” of spacetime faster than the speed of light. It’s just that if it’s expand everywhere by even a tiny amount, over vast enough differences, those tiny amounts will add up to greater than the speed of light. But that’s an artifact of distance, not speed, so it is not accurate to say that space can expand at a speed faster than light.
IANAP, but I believe the key to the answer is whether this hypothetical “warp drive”, whether an Alcubierre drive or anything else, can travel into the past. Since I think the realistic answer to that question is “no”, so is the answer to the OP question.
The problem is that the warping of spacetime around a black hole is so extreme that time drastically slows down as you approach the event horizon, and relative to an outside observer, at the EH itself time stops completely. Once you enter a black hole, extrapolating the field equations that define the spacetime geometry outside the black hole, it appears that space and time switch places in that the radial direction pointing to the singularity is now timelike.
That’s the fundamental reason you can’t escape from a black hole – it’s not because the escape velocity at the EH is equal to the speed of light, which is just a side effect – it’s because there is no longer a spacelike direction to “out”. It’s now timelike, and opposite to the direction of the arrow of time. If an Alcubierre drive can get out of a black hole, I want one – not because I plan on visiting any black holes, but just because there are quite a few stocks I’d like to go back in time and buy 20 and 50 years ago!
There is nothing special about the event horizon around a black hole. It is just the surface in space around the black hole where the curvature of spacetime is precisely such that the escape velocity is c. Further out the curvature is less, closer in it is more.
If you can travel faster than light though some mechanism, you can climb out faster than c, thus escape. Easy. Sort of.
If your mechanism for travelling faster than c is based upon performing some undefined warping of spacetime, you have to ask if your trick is capable of working if spacetime is already heavily curved the wrong way. If it only works when spacetime around you is mostly flat you have a problem.
Something based on negative energy might or might not be able to curve spacetime enough. In its simplest form one might guess it might curve things enough that you have a fighting chance of accelerating out.
Maybe the limit of negative mass is the inverse of an event horizon. Some arm waving appeal to symmetry might be invoked.
If so, even if it counteracted 99.99% of the curvature, you will need a conventional rocket that can get you up to 0.0001 c. And that is still ridiculously fast. So the answer may still be “no”.
Or your negative energy has the ability to curve spacetime as much as ordinary energy does, so arbitrary curvature.
The problem with this idea is just how much of this magical negative energy you need. One would assume it is symmetrical to ordinary energy. So you need the equivalent of minor planets up to stellar masses to do anything useful. Quite how that works for building a spacecraft is apparently left to the reader.
Your basic problem is how ridiculously stiff spacetime is. A warp drive would be fighting this just as much as ordinary mass energy is.
In the end it just comes down to how much magic you want to invoke. Magic involving narrativanium is a very potent source of spacetime warping energy.
