The Alcubierre drive is just a solution to the equations of general relativity that most probably can not be achieved in practice. Sure, maybe one day we will have drives like that, but we do not have any idea currently that even remotely resembles a warp drive permitted by the laws of nature.

That would require us to create matter with a negative energy density, which has never been detected and is likely impossible.

Still fiction; it relies on magic, i.e. things not known to actually exist.

Magic operates in ways we don't understand. I think we understand negative energy density, we just don't know if it's possible in reality.

> Magic operates in ways we don't understand.

Witches would disagree. :)

> I think we understand negative energy density, we just don't know if it's possible in reality.

Exactly as in magic. When you propose things are possible if only X material with some magical property necessary for thing to work, that's speculative fiction. Especially when those constructs only make sense mathematically. Math isn't physics, but physics is math, there's an important implication there.