But other calculations say that applies only in limited cases and that if you ramp up the warp engine slowly enough, you’ll be fine.

Yet more calculations sidestep all of this and just look at how much negative energy you actually need to construct your warp drive. And the answer is, for a single macroscopic bubble — say, 30 feet (100 meters) across — you would need 10 times more negative energy than all of the positive energy contained in the entire universe, which isn’t very promising.

However, still other calculations show that this immense amount applies only to the traditional warp bubble as defined by Alcubierre. It might be possible to reshape the bubble so there’s a tiny “neck” in the front that’s doing the work of compressing space and then it balloons out to an envelope to contain the warp bubble. This minimizes any quantum weirdness so that you need only about a star’s worth of negative energy to shape the drive.