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Old January 8th 13, 09:03 AM posted to sci.physics.relativity,sci.astro,sci.math
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Default About Time Travel and The Time Travel Paradox

If you try to construct a galaxy model or universe model where time
travel is possible without any paradoxes
you have to satisfy following two axioms C1 and C2 and the definition:

C1 (Locality). The laws of motion inside any region U do not depend on
anything outside of U.

C2. In any causal spacetime the laws of motion must be compatible with
any initial data.

Definition. The paradox is the inconsistency of some laws of motion
satisfying conditions (C1,C2) with initial data fixed in a causal


Krasnikov, S. 2002.
The time travel paradox.
arXiv:gr-qc/0109029v2 27 Mar 2002.
(C1 on p. 6, C2 on p. 7 and Def. on p.10.) pages 1-17.

My model of a galaxy mentioned in my Master of Thesis (Poropudas,
Hannu, 2006. Geodesic Algebras. Oulu University) satisfies all of

Best Regards,

Hannu Poropudas