Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum effects in the Alcubierre warp drive spacetime   The expectation value of the stress-energy tensor of a free conformally
invariant scalar field is computed in a two-dimensional reduction of the
Alcubierre ``warp drive'' spacetime. The stress-energy is found to diverge if
the apparent velocity of the spaceship exceeds the speed of light. If such
behavior occurs in four dimensions, then it appears implausible that ``warp
drive'' behavior in a spacetime could be engineered, even by an arbitrarily
advanced civilization.

37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph