Kerr & Tipler Cylinders: Time travel to the past?

[jesse_m98]

I did a bit of crude reading on the matter and it appears that this is plausible although there is no way to prove it at the moment:

 

Certain types of black holes also exhibit the "time travel" abilities of Tipler cylinders. Kerr was one of the first to describe the dual event horizons of a rotating black hole. As with Tipler's cylinders, it was possible to travel on a "time-like" trip through a Kerr black hole and end up in a different worldline without being squished by the gravity of the singularity.

The mass and gravitational field of a microsingularity can then be manipulated by "injecting" electrons onto its surface. By rotating two electric microsigularities at high speed, it is possible to create and modify a local gravity sinusoid that replicates the affects of a Kerr black hole.

I have only taken high school physics(so i dont know if i sound like a jackass), but this is under the assumption that the everett wheeler model is correct stating that all quantum states exists at the same time? Anything is possible, yes, but i just cannot see how paradoxes are not created and backwards time travel impossible... Would love some informed input on this

[ajb]

... but i just cannot see how paradoxes are not created and backwards time travel impossible... Would love some informed input on this

So it seems that in classical general relativity that time travel to the past maybe allowed. The situations are usually very set-up and often require strange forms of matter, but none the less time travel is not obviously outlawed. Of course one has the paradoxes associated with time travel to contend with.

 

When one adds quantum field theory to the mix, things become even less obvious. It seems that rather generically that quantum effects will destroy any time machines. However, this has I believe not been formulated and proved in proper generality, just case by case time machines are sick.

 

This has lead to the Hawking chronological protection conjecture, that basically says nature will never realise a time machine.