# Steering Alcubierre bubble?

So the question is - let's pretend we managed problems with exotic matter and/or energy (there are theoretical solutions without exotic matter, with only positive energy https://iopscience.iop.org/article/10.1088/1361-6382/abe692 , https://arxiv.org/abs/2102.06824) to create Alcubierre bubble. Can we steer the bubble by using said exotic matter/energy and by that change ship's spatial orientation for some observers, inside/outside of the bubble?

Note: talking only about subluminal bubble.

• IIRC, Alcubierre drives can't accelerate/decelerate on their own and may only move along pre-laid "tracks" of exotic matter. What you need is something like a railroad switch track.
– BMF
Sep 5, 2022 at 13:25

Surfing on a wave you make.

Alcubierre has shown that a ship using an Alcubierre drive travels on a free-fall geodesic even while the warp bubble is accelerating: its crew would be in free fall while accelerating without experiencing accelerational g-forces... Alcubierre interpreted his "warp bubble" in terms of a contraction of space ahead of the bubble and an expansion behind...

Gravity is the curvature of space. The Alcubieere drive in some respects in like artificial gravity. You fall into the contraction of space ahead of you. I picture it like surfing and falling down the front of a wave you generate.

If you generate it to one side you would fall to one side. The linked wikipedia says there are big tidal forces on the edge of the bubble so maybe sharp turns inadvisable.

• Under that interpretation, couldn't the ship accelerate at a constant rate for free forever? Sounds like a different drive system. Last time I looked at Alcubierre drives, they moved through space (FTL or not) on inertia and needed to be accelerated externally.
– BMF
Sep 6, 2022 at 8:15

Short Answer: rotate the mass/energy distribution that creates the bubble