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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.

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    $\begingroup$ 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. $\endgroup$
    – BMF
    Sep 5, 2022 at 13:25

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Surfing on a wave you make.

diagram of alcubierre bubble from wikipedia

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.

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  • $\begingroup$ 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. $\endgroup$
    – BMF
    Sep 6, 2022 at 8:15
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Short Answer: rotate the mass/energy distribution that creates the bubble

Long Answer: caution contains science

Alcubierre drives are a really cool, because it moves in a different way to ordinary space transport systems, which move the ship by "throwing" stuff in the direction opposite to were you want to go.

Alcubierre drives instead move by using matter and energy to distort space and time, which distorts the path an object takes through space. Normally if there wasn't any distortion the object would keep moving in what ever direction and speed it started with. But the Alcubierre drive distorts the path of the object so it so that any thing inside the bubble moves with the bubble.

The bubble is created by placing negative energy around it in a specific way, and if energy is arranged in this way you create a bubble, traveling in a direction specified by the arrangement of the energy. so if you rotate the arrangement of energy the bubble will now travel in that direction, dragging its contents with it. An added befit is that it is an inertialess drive meaning that objects contained within don't experience a force either speeding up of slowing down, or turning meaning that the contents isn't pushed to the edge of the bubble.

hopefully that helps

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