In this post, Peter Donis says:
My question is whether or not the distance between Earth and Alpha Centauri would actually be much less than 4.3 light years if measured along a path that passes through the Alcubierre warp bubble.
I understand that the Alcubierre bubble, by contracting space, shortens the distances forward, however, this shortening is permanently compensated by an expansion of the space behind, so the distance between Earth and Alpha Centauri would remain at all times...