Review: Now

 Now is Richard Muller's physics speculation about the nature of time. Richard Muller's an experimental physicist, so his opinion carries quite a bit more weight than the typical man in the street. Also, most other books about such speculations are written by theoretical physicists, so his is quite a different view, especially since he covers much of the experimental work that other books don't.

Since it's partly a speculative work, Muller doesn't abstain from providing discussions about what is or isn't physics and his quotes are frequently quite pithy:

Physics is arguably that tiny subset of reality that is susceptible to mathematics. No wonder physics yields to math; if an aspect of existence doesn’t so yield, we give it a different name: history, political science, ethics, philosophy, poetry. (kindle loc 3559)

He also points out several interesting things about say, the nature of black holes:

 Recall the calculation showing that it takes infinite time to fall into a black hole. A similar calculation shows that it takes infinite time to form a black hole, measured in our time coordinate. All that material has to fall, effectively, an infinite distance. So unless the black holes already existed at the moment the universe was created, unless they were primordial black holes, they haven’t yet reached true black-hole status; there hasn’t been enough time (from our outside proper frame) for the matter to fall the infinite distance that characterizes a true black hole. And there is no reason to think that any of the objects are primordial (although some people speculate that one or more might be). (kindle loc 1229)

Muller also doesn't hesitate to talk about how he's willing to consider things that are not provable by physical laws true. Ultimately, he provides his own speculation, that time is created by the expansion of the universe, similar to the expansion of space. He proposes experiments that might falsify his explanation one way or another, but doesn't discuss whether or not we're coming close to a conclusion. He dismisses many other approaches to the consideration of time, such as using the second law of thermodynamics, considering them not even wrong, since the use of such mechanism doesn't lead to any useful predictions.

All in all, I enjoyed the book and considered it well worth the time spent reading it. At the very least it's got an unusual, experimentalist bent that will be different from other works written by theorists.