Time Travel and Consistency Constraints

Kutach, Douglas (2002) Time Travel and Consistency Constraints.

Abstract

The possibility of time travel, as permitted in General Relativity, is responsible for constraining physical fields beyond what the laws normally require. In the special case where time travel is limited to a single object returning to the past and interacting with itself, consistency constraints can be avoided if the dynamics is continuous and the object’s state space satisfies a certain topological requirement: that all null-homotopic mappings from the state-space to itself have some fixed point. Where consistency constraints do exist, no new physics is needed to enforce them. All one needs for their accommodation is to grant a kind of law-like status to some kinds of global boundary conditions.