This book seems to be a good overview of physics in all its quantum aspects. I say seems to be because I simply don't have the mathematical background or scientific training to gain more from this book than an appreciation of how mind-blowing physics concepts are. I could see a motivated teen or college student using this to gain an overview of the history and different aspects of physics, as the author's tone is very conversational and approachable.

The First Law of Quantum Communication

The First Law of Quantum Communication is that all explanations of Quantum Mechanics for general audiences are really, really bad*. Sean Carroll's Quanta and Fields: The Biggest Ideas in the Universe is very different from every previous pop quantum mechanics explanation I have ever read. The question before us is whether it is an exception to the Law, or a uniquely creative new example.

Where I'm coming from: I am a retired neuroscientist and mathematician. I am familiar with and comfortable with quantum mechanics. I have also, to my sorrow, read dozens of pop physics explanations of quantum mechanics, because every pop physics book begins with the same tiresome six chapters intended to bring the presumed ignorant reader up to speed on relativity and quantum mechanics. And they are almost uniformly TERRIBLE. They are terrible for multiple reasons, but most of these come down to a determination on the part of the explainers to make quantum mechanics as confusing to a modern reader as it was to Niels Bohr and Werner Heisenberg when they first began to work it out. Physicists explaining quantum mechanics seem to feel a duty to make it as confusing as possible. If they have to ignore a century of progress and get crucial points wrong to do so, well, yeah, they're up for that.

I said "almost uniformly", because Carroll is the honorable exception. Unfortunately, I'm afraid quantum mechanics is not suited for the approach of The Biggest Ideas in the Universe. The general idea was explained in the first Biggest Ideas book, Space, Time, and Motion

"The Biggest Ideas in the Universe is dedicated to the idea that it is possible to learn about modern physics for real, equations and all, even if you are more amateur than professional and have every intention of staying that way. It is meant for people who have no more mathematical experience than high school algebra, but are willing to look at an equation and think about what it means. If you’re willing to do that bit of thinking, a new world opens up."

How does he propose to do this?

"Most popular books assume that you don’t want to make the effort to follow the equations. Textbooks, on the other hand, assume that you don’t want to just understand the equations, you want to solve them. And solving these equations, it turns out, is enormously more work and requires enormously more practice and learning than “merely” understanding them does."

So the approach of The Biggest Ideas is to show you the equations, but not to explain how to solve them. I thought this worked well in Space, Time, and Motion. But in quantum mechanics solving the equations is really a critical part of understanding what they mean. Carroll himself writes

"The quantumness of quantum mechanics, including quantum field theory, comes from solving the equations, not from the fundamental nature of the ingredients we use to construct the model."†

Elsewhere, when describing how quantum field theory explains particles, he writes

"And then the miracle occurs. Each mode of a quantum field behaves like a simple harmonic oscillator, including the quantized energy levels we previously uncovered. Those energy levels are interpreted as the number of particles we would observe: a mode in its first excited state represents one particle, its second excited state represents two particles, and so on."†

It is indeed almost miraculous. I remember seeing this in my first quantum field theory class, and it was SO, SO COOL! Unfortunately, if your understanding of the solution is "And then the miracle occurs", well, you don't really experience the miracle. Carroll tries to explain it in more depth than that, but I didn't feel that his explanations really worked, except for those who already understand them.

I enjoyed this. I learned quite a bit -- in particular it contains a particularly lucid explanation of renormalization.

Thanks to NetGalley and Penguin Group Dutton for an advance reader copy of Quanta and Fields: The Biggest Ideas in the Universe. Release date 14-May-2024.

*There is no "First Law of Quantum Communication", and if there were, it wouldn't be this.

†Quotes are from an advance reader copy of Quanta and Fields and may change before publication. This review will be corrected on the release date if necessary.

I’m not sure who this book is for. A lay audience who likes math, I guess? All the equations bore me to tears. I just want to understand the concepts. So this book is the opposite of what I’m looking for, but maybe others will enjoy it. The writing is good and the subject matter is interesting. Still, the suggestion in the introduction that the math has been pared down to the minimum feels like a painful irony.

Thanks, NetGalley for the ARC.