By warp drive I mean the usual Alcubierre formulation.

Probably? The features of physics that make a black hole inescapable are the same features that make FTL or time travel impossible, just curled around into a spherical shape. But there’s a lot that we don’t know about how an Alcubierre drive, or the exotic materials that would be needed to make one, would behave, so no definite answer is possible.

For the sake of the usual fictional narratives that surround warp driven spacefaring and black holes, it would be safe to assume that a warp drive won’t get you out. It would be too boring if it did.

Even the Tardis has problems with black holes, making for lots of shouty drama. Although not always. Deuce ex machina plot devices avoid authors needing to think all that hard.

Well, since we’re speculating about the capabilities of a device that is itself highly speculative and, in my view, impossible, I’ll offer the following speculation. That the answer is yes, an Alcubierre drive might be able to escape from inside a black hole, but only in one specific and strange way.

One observes that due to the extreme warping of spacetime beyond the event horizon, one interpretation of the Einstein field equations beyond the event horizon is that time and space have changed places. One way of conceptualizing why there is no escape from a black hole is because there is no “out” direction; that has now become a time dimension in the spacetime geometry inside the BH. Fortunately, the Alcubierre drive, by achieving superluminal speeds, violates causality and must be capable of traveling back into the past.

Thus we have the happy situation where the Alcubierre drive can take our intrepid astronaut out of a black hole, but without violating the cosmic censorship hypothesis. That is, our astronaut can return from the black hole, but only to a point in time before he entered it. Thus, he can’t tell us anything about the interior, and so no information has been extracted from beyond the event horizon. Worse still, our astronaut may now be caught in a cosmic time loop. It’s a good thing the Alcubierre drive is impossible, because it’s fraught with peril!

You’re only saying that because there are two of them.

I’m not sure the reasoning behind either of these sentences. The astronaut must return “before” he left, in the sense that he’s going to a higher r value, but that doesn’t imply a lower t value. And even if he did come out before he went in (which is certainly possible), why couldn’t he tell what he saw?

Darn. That is auto spell correct really messing it up.

When you drop a deuce out of a machina, you should clean it up immediately.

This sort of speculative fiction does not belong in Factual Questions. The question is akin to, if a non-existant fantasy space drive were to be developed and work, what would happen if monkeys flew out of my butt?

There is no Warp Drive and probably never will be.

The first part is premised on the idea that one interpretation of the spacetime geometry inside a black hole is that the radial dimension pointing towards the singularity is now timelike, and that direction is the inevitable future. The opposite direction, pointing out of the black hole, is the past.

On the last point, I was not envisioning time travel into the past in the usual sci-fi sense of an individual as presently constituted traveling back into the past. I meant it in the more formal sense of actually running the clock backwards. Thus our astronaut has been rescued from the black hole in the only possible way he could be, and he cannot tell us about his adventure inside because he literally has not been there yet.

Are the monkeys in a warp drive capable craft?

Warp drive on a treadmill.

In practice? Probably no. But there is actually a theoretical solution to the equations of General Relativity, the Alcubierre metric referenced in the OP, that can fairly be described as a “warp drive”. There are good reasons to believe that it’s not actually possible to build an Alcubierre-powered ship, but it is actually possible to scientifically answer questions about how such a ship would behave, if it were to exist.

And in future, if you believe that a thread is out of place in FQ, please just report it.

If we can build an Alcubierre drive, then we have a source of negative mass-energy. And if we have that, we can shrink the black hole to nothing just by throwing in a bunch of that negative mass.

Maybe that doesn’t count since you’re just moving the event horizon instead of crossing it. But I suspect that would be the case anyway–if you could travel in and out, it would amount to distorting the EH so that you never actually cross it; you just kinda push it out of the way.

Hm, maybe… Though the amount of negative mass (or more precisely, the absolute value of the amount of negative mass) for an Alcubierre drive can be much, much less than the amount of normal mass of the ship, so the total mass is still quite positive. It’s hard to see how that could result in any inward distortion of the event horizon.

Though, come to think of it, the Alcubierre metric is itself just a distortion of spacetime, and the mass within the bubble is just behaving like normal mass. So I suppose that the proper view would be to consider the bubble plus the hole as the description of the spacetime, and define the horizon based on how matter moves within that entire spacetime…

Is that known for sure? The Wikipedia page seems a bit all over the map:

If certain quantum inequalities conjectured by Ford and Roman hold,[30] the energy requirements for some warp drives may be unfeasibly large as well as negative. For example, the

energy equivalent of −10^64 kg might be required[31] to transport a small spaceship across the Milky Way—an amount orders of magnitude greater than the estimated mass of the observable universe. Counterarguments to these apparent problems have also been offered,[3] although the energy requirements still generally require a Type III civilization on the Kardashev scale.[12]Chris Van Den Broeck of the Katholieke Universiteit Leuven in Belgium, in 1999, tried to address the potential issues.[32] By contracting the 3+1-dimensional surface area of the bubble being transported by the drive, while at the same time expanding the three-dimensional volume contained inside, Van Den Broeck was able to reduce the total energy needed to transport small atoms to less than

three solar masses. Later in 2003, by slightly modifying the Van den Broeck metric, Serguei Krasnikov reduced the necessary total amount of negative mass toa few milligrams.[3][27] Van Den Broeck detailed this by saying that the total energy can be reduced dramatically by keeping the surface area of the warp bubble itself microscopically small, while at the same time expanding the spatial volume inside the bubble. However, Van Den Broeck concludes that the energy densities required are still unachievable, as are the small size (a few orders of magnitude above the Planck scale) of the spacetime structures needed.[24]In 2012, physicist Harold White and collaborators announced that modifying the geometry of exotic matter could reduce the mass–energy requirements for a macroscopic space ship from the equivalent of the planet Jupiter to

that of the Voyager 1 spacecraft (c. 700 kg)[15]or less,[33] and stated their intent to perform small-scale experiments in constructing warp fields.[15]

So, anywhere from 10^64 kg to three solar masses to 700 kg to a few milligrams… except that the latter option seems to still require impossible energy densities. So even if you can buy a pail of negative matter at the corner drugstore, I’m not sure you could actually fashion it into one of the minimal-mass versions without also compressing it into something like a negative black hole.

The Krasnikov result was the one I was remembering (amusingly, it works by putting the warp drive in a TARDIS). I either never noticed or didn’t remember the densities that required, though, which would indeed undoubtedly have… interesting… effects.

This is the better way to think about it. And it means that the answer to the title question is actually “no” for a stupid technical reason.

The event horizon of a black hole is **defined** to be the boundary of the region of spacetime from which objects cannot escape to future infinity. That means that you can never exit the event horizon, because if you can get out to infinity you weren’t inside the event horizon in the first place. If we were to send an Alcubierre-type spacecraft towards a black hole, and it noodled around near the black hole for a while and then came back out, then by definition it was never inside the event horizon. The distortion of spacetime from the “warp drive” would affect the event horizon in the process, in such a way that the ship itself was never inside the horizon.

The more interesting question is “if we had a black hole and we sent an Alcubierre ship towards it, could it pass through points in spacetime that would have been inside the event horizon in the absence of the ship’s warp bubble?” And I’m honestly not sure how to address that question, to be honest. Comparing two different spacetimes is a difficult process, mainly because coordinates don’t have any inherent meaning in general relativity. Even if the spaceship passed through the point (4, 10, -3), and the point (4, 10, -3) would have been inside the event horizon of the original black hole, that doesn’t mean that these two labels necessarily refer to the “same point” in the two versions of the spacetime.

So this is a pretty non-satisfying answer, but that’s because it’s a non-trivial and interesting question.

You may be right that there probably never will be, but this is not all speculative fiction. In the interest of fighting ignorance, and for the benefit of anyone who hasn’t heard of the Alcubierre drive, allow me to explain.

The Alcubierre drive is a theoretical construct that was derived from Einstein’s equations by a physicist named Miguel Alcubierre in the 1990s. The Alcubierre drive is, as far as our current understand of physics goes, consistent with Einstein’s equations of general relativity.

Objects cannot accelerate to the speed of light in normal space (or spacetime, if you prefer) and the Alcubierre drive does not actually violate this. Instead, the idea is to create a wave through space, and having your “spaceship” ride this bubble through the compressed and expanded space that results from the wave. Or in other words, the idea is to warp space itself so that the object does not need to exceed the speed of light. However, from an external observer, the object does end up traveling at speeds significantly greater than the speed of light.

It’s a rather clever theory, IMHO.

My understanding of the physics of it all is admittedly a bit iffy, but I believe one key factor in all of this is that negative energy must be used. Alcubierre claims that this can be derived from the Casimir effect. If Alcubierre is correct, then “warp” drive technology is theoretically possible. Well, maybe. If Alcubierre is wrong, then the whole theory falls apart and all of this ends up being a discussion about useless mathematical implications.

The jury is still out on Alcubierre’s theory. But if the theory is correct, the FQ question here is based on what the implications of that would be in the OP’s specific scenario. This is a physics question, not sci-fi speculation.

If you want to know more about the physics being discussed here, wikipedia has a couple of articles that you might want to read:

There are monkey boys in the starship.