I have just finished reading this book, with the rather bold subtitle, by a Physics Nobel Prize winner (originally published in 2005, although my paperback from Basic Books is from 2006).
It is a bit hard to know what to think about it. It starts off with a very strong program, and makes some very persuasive arguments early on, but in the end I am not sure whether it lived up to the expectations. It’s not that I disagree with the author (as a complete amateur in the field of Physics, how could I?) but that the book frequently presents strong claims without similarly strong arguments to back them up. Instead it often makes some rather general points, or tells some vaguely related anecdote, as if it assumes that the rest of the argument is self-evident or something the reader should already be familiar with.
But, if this sounds negative, I should stress that I nevertheless enjoyed reading it very much (not least due to those anecdotes).
The basic thesis of the book is that the search for the ultimate truth in Physics (and other fields) through the reductionist search for smaller and smaller “elementary” components is mis-guided because the fundamental truth occurs through a process of organization, that is emergence—the main theme of the book—at a higher level.
In Physics this means at the level where you have a largish number of atoms or molecules, such that, for example, the phase of matter—e.g., solid, liquid or gas—is established, and quantum weirdnesses are irrelevant or insignificant. When the number of atoms is much smaller than this, you cannot really tell if you have a liquid or a gas, and the position and motion of individual atoms are unknowable by the uncertainty principle. This, and the fact that there is no sharp boundary between these “small” and “large” territories, is well known and one source of the conceptual difficulties with quantum theory.
Well, my understanding is that the opposite of reductionism is holism, which in this case should mean taking in the whole of reality—small and large—in a single unified framework. In other words, rather than saying the fundamental truth lies at some particular, preferred level, to understand and explain all the levels, from the quarks to the cosmos, and how they are connected, in one go. But isn’t this basically what mainstream physicists are trying to do, with their search for grand unified theories of everything?
Part of the ultimate truth must therefore be to actually explain this emergence. How does it come about? How do the physical characteristics of matter, time and energy transition between the small (quantum mechanical), the large (emergent) and the super-large (cosmic)? Again, this seems to be a busy research area, though, under the headings of chaos and complexity.
The main value of this book is as a realist, down-to-earth antidote to all the whackier attempts to extrapolate the quantum uncertainties to large-scale effects—such as the “theory” that every time any particle makes a random move under quantum rules the whole universe instantly splits into multiple copies for the different options available to this particle. The absurdity of such an idea just shows that the extrapolation actually doesn’t work, and that there is therefore something missing in the underlying theory, however well it works in the atomic-sized domain.
Anyway, the next book I am reading now is Lee Smolin’s “The Trouble with Physics“, which, judging by the introduction and first couple of chapters is also going to address the problem with the current state of Physics (basically, that following about 200 years of regular important discoveries, there has been no significant advance since about 1970). One of the themes stressed early on in this book is the importance of going back to basics, and history, to understand what has driven scientific revolutions (in particular earlier unifications), and to stress the actual, practical importance of falsifiability and other requirements to scientific theories. I am curious to see where this goes.