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It’s been a long time since I read any Paul Davies. I seem to recall finding his Mind of God from 1992 interesting, but other than an IAI talk alongside Sabine Hossenfelder, I haven’t heard much about him since the 90s. This book also dates from that time (1995) so I wondered how relevant it might be today. But this pristine hardback was only two dollars at the used bookstore � how could I pass that up?

Even though this mostly duplicates material I’ve read elsewhere over the years, the one thing that struck me right away in the opening chapter is how Davies provides for a very clear image of the subjects he discusses. Nothing fuzzy or hazy. Probably the most clearly described explanation of time dilation and twin paradox that I’ve ever read. If you’ve ever struggled with conceptualizing Einstein’s relativity, this is the book for you. So, in that regard, this is strongly recommended for those young or old who are just starting out on their scientific journey.

I would suggest starting with the author’s list of a dozen outstanding puzzles about time, found on pages 280-283. This will whet your appetite for what the book will present as a gluttonous multi-coarse feast.

Davies spends an entire chapter on the Wheeler-Feynman calculations for the time-asymmetry enigma (advanced and retarded wave propagation) and the past-future ambiguity of kaons. By the end we end up where we started: it would seem impossible to circumvent the straight arrow of time (now we have the calculations to prove it). Apart from some funny stuff with tachyons and the possibility of sending encoded messages to the past, time travel in any sort of physical form (with matter) is not possible. That is why I appreciate when science fiction writer Alastair Reynolds creates a clever time-travel story in his Eversion that doesn’t violate these principles. This is all rather esoteric stuff that doesn’t move us forward on any of the important issues, but I found it entertainingly clever nonetheless.

Also entertaining are the stubborn Doubting Thomas interjections which permeate the narrative. A clever way to finesse and explain issues from another perspective. I also liked the section on how philosophers have dealt with the subject of time in the past, with a quote from philosopher Michael Lockwood: “No position is so absurd that a philosopher cannot be found to argue for it.�

All in all an exceedingly well-written book, most appropriate for those seeking general enlightenment, but also full of anecdotes and esoteric minutia to keep the more seasoned reader engaged.