Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cosmic String Lensing and Closed Time-like Curves   In an analysis of the gravitational lensing by two relativistic cosmic
strings, we argue that the formation of closed time-like curves proposed by
Gott is unstable in the presence of particles (e.g. the cosmic microwave
background radiation). Due to the attractor-like behavior of the closed
time-like curve, we argue that this instability is very generic. A single
graviton or photon in the vicinity, no matter how soft, is sufficient to bend
the strings and prevent the formation of closed time-like curves. We also show
that the gravitational lensing due to a moving cosmic string is enhanced by its
motion, not suppressed.

25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex