Logic, Quantum Computation and Quantum Gravity

"Whether or not time travel could ever become a practical proposition, just thinking about it, in the context of the Everett interpretation of quantum mechanics, is very illuminating. The fact that going back in time invariably means going sideways in actuality highlights an important truth: namely, that the parallel realities that arise within the Everett interpretation of quantum mechanics are not discrete entities... Studying the geometry of this continuum should prove a fruitful and fascinating line of research for the more avant-garde physicists of the twenty-first century."

Michael Lockwood,  The Labyrinth of Time.