Paul Davies: About Time: Einstein's Unfinished Revolution (1995)

Edition: Viking, 1996
Review number: 424

About Time is an eminently readable popular account of the current ideas about time in physics, with a short historical section examining philosophical perceptions of time from the ancient Greeks to the time of Newton. The main concerns of the book are to explain the role played by time in the keystones of modern physics, general relativity and quantum mechanics. Since much of physics is concerned with processes, time can be used as a single theme to motivate a discussion of many of the more interesting aspects of modern physics.

The nature of time and its role in the cosmos also lie at the heart of some of the unsolved problems of physics, many people thinking that these issues will provide the key to the next generation of physical theories. Most prominent among these is the asymmetry of time, a major problem when underlying theories would be unchanged if time ran backward rather than forward. In slightly different areas, issues of human perception of time are briefly touched upon as well as what exactly we might be measuring with different kinds of clocks.

The descriptions of relativistic and quantum effects are now the commonplace of popular physics, and the most interesting parts were those dealing with more unusual matters, such as the nature of the interior of black holes or the asymmetry in kaon decay. The device of having a second voice used as a sceptic to facilitate the discussion is slightly annoying but not a big problem.