Time travel technology is easy.

[fizz_]

Alter the ambient aether density. High density(high pressure) aether fields speed up time. Low density(low pressure) aether fields time slows down, stop and reverses if strong enough.

Figure out how to do that and you got it.

 

[PeK]

There has been no evidence of aether, so that might pose a problem or 50.

 

[fizz_]

Aether is an invisible form of super tiny hydrogen. Can materialize it.