Is it possible to define unambiguously retarded and advanced Green's function(adsbygoogle = window.adsbygoogle || []).push({});

in spacetime without timelike Killing vector. Most often e.g. retarded Green

function [tex]G_R(t,\vec{x},t',\vec{x}') [/tex] is defined to be 0 unless t'<t

but maybe one can express this condition using only casual structure

(without time coordinate)?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Green's function for Klein-Gordno equation in curved spacetime

**Physics Forums | Science Articles, Homework Help, Discussion**