## Rotating Universes and Time Traveling

From: "andrew cooke" <andrew@...>

Date: Wed, 8 Feb 2006 07:20:40 -0300 (CLST)

A good introductory article on Godel Universes -
http://www.ettnet.se/~egils/essay/essay.html

In 1949 Kurt Gödel found a cosmological solution to Einstein's field
equations with rotating matter. The lesson to be learnt from that is
that the relation between galaxies and the inertial system is more
intricate than common-sense believes. Mach's principle is only poorly
incorporated in Einstein's theory.

[...]

Gödel's universe has another property that is perhaps even more shocking:
It allows traveling backwards in time (although the practical difficulties
would be more than overwhelming). You enter a rocket, and you take a
journey in the universe along a certain path. Then you will - after many
billions of years - return to the starting point before you started.

Andrew