| One of the things that I explore in Worlds in Transition, in the story Parallax, is the idea of quantum entanglement. It turns out that this idea is central in resolving one of the biggest problems in quantum mechanics: that the direction of time is not set, and that causality is not actually a fundamental physical law.
Some physicists, including John Cramer, a science fiction writer, now propose an experiment which if successful, could actually tell whether future as well as past events can effect the outcome of an event in the present. New Scientist has this interesting article in Retrocausality.
Here's another article about Ron Mallett, a physics professor at U-Conn who has not only proposed time travel, but has built a model Time Machine. Ron uses the idea of "Frame Dragging" to create TLCLs (Time-Like-Closed-Loops) in space-time using a circulating laser. The Frame Dragging effect predicted by General Relativity is also the subject of Gravity-Probe B, an experiment I worked on. So here it is, Time Travel.