World According To Quantum Mechanics, The: Why The Laws Of Physics Make Perfect Sense After All [Hardcover]

Richard Feynman famously stated "I think it is safe to say that no one understands Quantum Mechanics."

This book is changing that. Although so far I have only read up to chapter 5, it looks like this unexpected treatise lives up to its preposterous subtitle.

The way Ulrich Mohrhoff introduces QM everything flows from the basic rules of calculating with probabilities and the uncertainty relation. The latter in turn is a logical requirement for stable matter and quite a misnomer in English (surprisingly the original German term "Unschaerferelation" captures its meaning significantly better).

Reading chapter 5 has been a most humbling experience. I studied physics and have always been captivated by the particle wave dualism that the classical two slit experiment embodies so beautifully. Feynman observed that this "experiment has in it the heart of quantum mechanics". Well, I feel like eating my heart out.

The way this book covers the two slit experiment everything falls into place and makes perfect sense. There is no wave particle dualism, just the naked necessity of a probabilistic regime. It is so simple. Painfully obvious. Easy to grasp with just a minimum of mathematical rigor. It boggles the mind that QM has not been understood this way from the get go. This feels like 20/20 hindsight writ large.

To add insult to injury, this is written as a text book that'll be easily accessible for an enterprising high school student, because it briefly introduces all necessary mathematical tools along the way. I.e. a physicist can easily skip these parts as they are cleanly separated from the chapters in which the author executes his QM program.

If you've been trying to make sense of QM you will hate this book. It'll make you feel stupid for not having been able to see this all along. Time to eat some humble pie.

I'll report back once I read the rest.

For those who have been following Mohrhoff's revealing ideas during the last decade (the so called "Pondicherry Interpretation of Quantum Mechanics"), this book adds a few very important points to what is already one of the most comprehensive and consistent interpretations of the fundamental laws of physics that anyone has put forward up to the present date.

He obviously didn't start this journey one fortunate Monday morning. He is following the steps of people like Bohr, Peres, Mermin and many other physicists who have contributed greatly to one and the same philosophical project: the de-reification of quantum-mechanical correlation laws, and the enormous implications that this carries for our understanding of physical reality.

This book is probably the best synthesis of that long-standing project. Its merit not only lies in taking a few isolated ideas about QM's probability algorithms and integrate them into an overall consistent view, which would be a huge achievement in itself, but first and foremost, to explain classical mechanics and classical conservation laws as part of (in the limit of) that same fuzzy state of affairs.

In this way, he very cleverly differentiates between what an equation of continuity says and what a local conservation law is, basically "a feature of our calculational tools". Key concepts like energy and momentum are introduced as underpinning the homogeneity of time and space respectively, instead of being just symbols in an abstract equation. On the other hand, the deceptive idea of force, deeply entrenched in our perception of a physical world, is redefined in a way that permits us to make sense of the Lorentz force law and the gravitational force as not being a mediating agent between causes and effects.

This is a profound, exhaustive and very well organized textbook, which should be of interest to anyone with a previous background in physics or, even better, to anyone who has not yet been contaminated by the mainstream habits and tricks of philosophy of science and crash undergraduate courses in QM. You won't find here any of the fancy stuff that philosophers like to talk about (backwards causation, many minds, many worlds and many papers), but it will give you enough substance and plenty of material to think about for the next ten or twenty years. At the very least, it will give you the basic tools to approach any other interpretational strategy with the necessary dose of scepticism and awareness. As the author correctly stresses, there is "no need to make the world stranger than it is".

The style is not as incisive and confrontational as most of Mohrhoff's shorter works, which is a bit of a disappointment, but understandable giving that this book is aimed at the general public. In years to come, "The World According to Quantum Mechanics" will be taken for what it is: a serious and courageous challenge to our fundamental ideas about the fabric of space and matter.