[pdonis]

> Does an Alcubierre warp drive violate causality?

The original Alcubierre metric does not, but that's because it only describes a single "warp bubble" that travels in one direction, never starting or stopping and never turning around.

As soon as you have more than one "warp bubble", or you let a single "warp bubble" turn around, then you will have closed timelike curves, which violate causality.