by Paul Davies
Paul Davis is one of those names that people who read about time travel theory get to know well. The description says:
"This is a book about the meaning of time, what it is, when it has started, how it flows and where to. It examines the consequences of Einstein's theory of relativity and offers startling suggestions about what recent research may reveal."
This about sums it up. Davies takes us through a rabbit hole of fascinating theory and current knowledge of related Physics that is easy to follow, if mind-bending in its content.
He extrapolates on relativity and explores concepts of worm holes and time warps, sharing some of his own experiences of visiting research sites discussing various theories about time travel.
If this is a subject you're interested in, this is one of the books you really need to read. Davies keeps it accessible for the non-Physicist and holds interest on what is a very academic subject.