Cosmic Strings and Closed Time-Like Curves in Teleparallel Gravity

TL;DR

This paper investigates the conditions under which closed time-like curves can exist in teleparallel gravity, showing they are generally forbidden and establishing bounds on cosmic string angular momentum, thus constraining time machine possibilities.

Contribution

It demonstrates that CTCs are forbidden in teleparallel gravity and derives bounds on cosmic string angular momentum, contrasting with previous results in Einstein-Cartan gravity.

Findings

CTCs are forbidden in teleparallel gravity.

A lower bound on cosmic string angular momentum is established.

Time machine formation is more constrained than in Einstein-Cartan gravity.

Abstract

Closed Time-like curves (CTC) in Cosmic strings in teleparallel $T_{4}$ gravity are forbidden.This result shown here in $T_{4}$ was shown by Soleng (Phys.Rev.D49 (1994)1124) also to be valid in Einstein-Cartan (EC) gravity.Here we show that in $T_{4}$ to allow for CTC we are also led to a lower bound on the angular momentum of the cosmic string.This result is obtained by matching the interior $T_{4}$ solution to a General Relativity (GR) vacuum solution.One of the main differences of the present report and the one by Soleng is that here the interior symmetric solution does not have necessary polarized spins but only Cartan torsion in the spirit of teleparallelism.Torsion flux is computed and it is show that the center of cylinder singularity corresponds to a 2+1 spacetime rotating point particle in $T_{4}$.Therefore the possibility of building time machines seems to be strongly constraint than in the case of EC gravity.