Constants of Nature

This book deals with mind-boggling questions about how the universe works, whether there are other universes besides our own, and even whether the laws of physics are really immutable. The 'constants' referred to in the title are the numbers that define the universe. A constant, says Barrow, is a 'pure' number; something that has a dimension, such as speed or length, cannot be a constant because its numerical value changes with the units in which it is expressed. The speed of light, which might seem like a constant to the layperson, is not really a constant at all because it could be expressed as 186,000 miles per hour or 300,000 kilometres per hour. On the other hand, the number of photons per proton, and the ratio of dark to luminous matter densities, are constants. Barrow, a professor of physics, leads us through a history of modern physics and its attempts to define and understand constants, outlining the work of theorists such as Planck, Einstein and Dirac. He does his very best to make the text accessible, peppering it with quotations from Oscar Wilde and Douglas Adams, using analogies with readily understandable ideas (such as traffic flow) and including lots of diagrams and pictures. Unfortunately, the subject matter itself is so difficult that it is almost impossible to follow the argument in all its detail unless you have a good grounding in mathematics or physics. As a lay reader, even if you grasp the basic ideas - the importance of constants, the search for a Theory of Everything, the possibility of different universes - you are very unlikely to understand the mathematics that illustrate Barrow's argument. Nonetheless, this is a book worth persevering with, because even if your brain aches at the end of it, you will have discovered what modern physicists are thinking about - and some of their current theories about the way the universe works are truly startling. (Kirkus UK)