Smoothing and extending cosmic time functions
Abstract
Any continuous time function on aC ^{ k } spacetimeV (i.e., a scalar onV that increases along any causal curve) can be approximated by smoothC ^{ k } time functions. A time function defined on a (bounded) subset of a stably causalV can be extended to a time function on the whole ofV.
 Publication:

General Relativity and Gravitation
 Pub Date:
 October 1977
 DOI:
 10.1007/BF00759586
 Bibcode:
 1977GReGr...8..815S
 Keywords:

 Astrophysics;
 Relativity;
 Smoothing;
 SpaceTime Functions;
 Applications Of Mathematics;
 Hyperbolic Functions;
 Hyperspaces;
 Astrophysics