Would Alcubierre Drive Technology Allow for Artificial Event Horizons?

The Alcubierre drive not only allows but actually necessitates the production of event horizons at superluminal speeds - but not necessarily the sort you're looking for.

It's been shown (Finazzi et al. 2009) that once an Alcubierre drive exceeds the speed of light$^{\dagger}$, two event horizons form, one in the front and one in the back. The horizons are, in a sense opposites, with surface gravities of opposite signs and opposite causal connections with the rest of the universe. The horizon in front is, for lack of a better description, like a black hole: matter from inside the bubble cannot travel forward through it out of the bubble. The horizon in back is, similarly, akin to a white hole: matter from outside the bubble cannot travel through it into the bubble.

These are both true relativistic horizons. While the entire bubble is not wrapped in a single one-way horizon like a black hole is, there are still two boundaries dictating the causal structure of space-time and restricting the motion of light and matter. Whether you could modify the Alcubierre metric to form a single horizon seems unlikely; it's a toy model existing in a universe with no outside matter, and modifications would be quite complicated.

On the other hand, a civilization that can build an Alcubierre drive must be able to handle the exotic matter required for its construction and operation might be able to form artificial event horizons in some other manner. If you look at other spacetime metrics, you might be able to find a starting point.

$^{\dagger}$ At subluminal speeds, these horizons disappear. This has the advantage of potentially making it possibly to actually control and steer the drive.

posted over 4 years ago

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