This book reflects upon the various elements that any Theory of Everything (ToE) would have to reconcile. A ToE is the holy grail of physics, a theory that would unify the various forces to explain the nature of the universe as we experience it. There have been many attempts to achieve a ToE, but it remains elusive. There is the mathematically beautiful and elegant string theory that suffers that one drawback of having no experimental support. There are those who have given up on a ToE in the sense that the term is normally used, suggesting that the desired degree of unification isn’t possible and that the desire to think it must be is just wishful thinking.
Probably the most useful piece of information about this book for one considering reading it is its readability. As works of popular science go, it’s more challenging that most (but not as difficult as, for example, Hawking’s “A Brief History of Time.”) [I have little doubt that those who read physics textbooks will find it a walk in the park.] It has few equations, and the mathematics it does present is elementary. However, it does explore quite complicated ideas. The book uses graphics to assist, mostly diagrams, but many of these require thoughtful consideration in their own right.
The organization of the book is based on an eightfold way (no relation to the Buddhist eightfold path) – that is, eight ingredients with which a ToE must be consistent. The nine chapters of the book begin with a brief opening chapter that sets up the rest of the book by discussing what a ToE would really explain (“everything” isn’t necessarily the answer in a strict meaning of that word), what the eight components are, how pre-scientific ToE’s operated, as well as introducing the recurring concept of algorithmic compressibility. (The importance of compressibility lies in the idea that in order to make the equations describing the universe more concise it’s necessary that the data describing the universe be “compressible” – i.e. have some underlying order.)
After the intro chapter, the eight subsequent chapters are logically arranged into the aforementioned eightfold way. These are: 1.) laws, 2.) initial conditions, 3.) the nature of forces and particles, 4.) the constants of nature, 5.) symmetries and the breaking thereof, 6.) organizing principles, 7.) Bias and selection effects, and 8.) to what extent mathematics is integral to the universe. Some of these elements (e.g. the laws and constants) we are told couldn’t vary by much and allow us to still exist. So, the question addressed in the book isn’t only how can science get to a theory that explains the existence of a stable(-ish) universe, but further one that can support complex and intelligent life. The chapters on symmetry breaking and selection effects are particularly relevant to this discussion.
One of the most interesting discussions is the last. Chapter nine, entitled: “Is ‘pi’ really in the sky?” discusses the question of how fundamental mathematics is to the universe. It’s long been a topic of scientific intrigue that there seems to be no particular reason for mathematics to be as effective as it is at describing the way the universe works. The discussion has resulted in a wide range of replies from those who say the success of mathematics is more illusory and limited than it appears to be, to those who believe the universe not only is written in mathematics but is math (see: the work of Max Tegmark.) That is, some say that there are parts of a stable universe that must be orderly enough to be described mathematically and those are the only parts we truly understand as of yet. Others say mathematics is the bedrock of the universe.
I enjoyed this book, and found the organizational approach helped a great deal in thinking about the problem. I doubt I grasped everything the author was trying to convey, but it was a book piled high with food for thought for anyone interested in thinking about the nature of the universe. If you’re interested in the grand-scale questions, I’d recommend this book. That said, there are more readable takes on the subject out there if one is looking for light pop science fare.