What Are the Most Plausible Theories for Time Travel?

[mitch_glinton]

Hi,

I am currently working on a project over the summer, entitled 'The physics of time travel'. One of the first things I need is feedback from academics and students involved in physics. Are there any texts/books I should be reading? Also, it would be great if anyone has the time to fill in my questionnaire on the likelyhood of the theories.

Thanks

my email is mitch_glinton@hotmail.co.uk

1. Please rank 1-6 (1 being most), the plausability of the following theories allowing time travel...

Parrelell Universes
Faster than light travel
Higher dimension travel
Black Holes/Worm Holes
Time machine
Other (please specify)

2. Please rank 1-6 (1 being most), the amount of scientific evidence of the following theories allowing time travel...

Parrelell Universes
Faster than light travel
Higher dimension travel
Black Holes/Worm Holes
Time machine
Other (please specify)

Thankyou

 

[Dr Lots-o'watts]

These are my own opinions :

Plausability or evidence:

Parallel Universes - Undetectable, so not arguable.
Faster-than-light travel - 6
Higher-dimension travel - 6
Black Holes/Worm Holes - 1 for black, WH Undetecable, so not arguable.
Time machine - According to SR, 1 for going in the future, 6 for going into the past. Practically though, 6 for both.

 

[QuantumPion]

There's a good lecture about the physics of impossible things, including time travel, here:
http://www.perimeterinstitute.ca/in...t&task=view&id=551&Itemid=568&lecture_id=7317

 

[JDługosz]

One thing to understand is that you get "problems" regardless of the mechanism in use.

I would wager that causalty reversal is impossible on a deep level, e.g. some kind of axiom. So it might be hard to prove other than that laws of physics always seem to conspire against it. Perhaps something like LQG will end up being based on organizing principles of a single direction of cause-and-effect as a primitive concept that makes our spacetime emerge.

Parrelell [sic] Universes - plausible

Faster than light travel - fundamentally impossible

Higher dimension travel - no, the "higher dimensions" are curled up so you end up going nowhere in the normal three.

Black Holes/Worm Holes - warping of spacetime is allowed as a solution of GR, but it might be ruled out via other mechanisms.