The universe is big. Mindbogglingly big. Our minds have trouble conceiving of the vastness of the universe, on either scales of time and space, or their unified presentation as spacetime. And the moment we think we might possibly be able to get used to this idea, it becomes apparent that the very foundations of our universe are small. So small, so tiny, that the energy required to probe these depths is nearly as impressively vast as the scale of the universe they conspire to create. This is The Quantum Universe that Brian Cox and Jeff Forshaw want to explore with us.
Quantum mechanics is notorious among physicists and laypeople alike for appearing to be nonsensical and unintuitive (or at least counter-intuitive). The chapter titles of this book illustrate this line of thought: “Being in Two Places at Once,” “Everything That Can Happen Does Happen,” “Movement as an Illusion,” etc. But such ideas are fundamentally biased by our perspective as macro-sized beings. If we experienced the world at the quantum level, then quantum mechanics would seem quite normal. Since our larger world is based on the confluence of so many quantum-level events, the picture this builds up is so far removed from those quantum effects that we get a false sense of reality.
So Cox and Forshaw follow Heisenberg in establishing that
the job of quantum theory should be to predict directly observable things…. It should not be expected to provide some kind of satisfying mental picture for the internal workings of the atom, because this is not necessary and it may not even be possible.
This is really difficult to accept. I know because I read a lot about physics and science, and I still picture a really tiny, featureless sphere when I picture an electron. But, of course, the whole idea of “picturing” an electron is the part that doesn’t make sense. Particles are not solid lumps of matter that happen to be really small. Particles are waves and waves are particles because both are descriptions of specific phenomena, often at a particular space and time in the universe.
Cox and Forshaw do a pretty good job, then, of deconstructing this false notion of particles. I also appreciate how they ground this deconstruction in the historical development of quantum mechanics. I knew the names, and had a vague idea of what the heavyweights behind quantum mechanics were known for—Heisenberg’s uncertainty principle, Rutherford and the structure of the atom, Dirac and antimatter, Schrödinger and the wave equation, etc. But Cox and Forshaw provide a more detailed context and chronology. They would describe, for instance, how Rutherford quickly realized the solar system model of the atom was wrong, or how Born or Dirac or Feynman would feed off each other’s discoveries very quickly. The 1920s was a really interesting time in the rapid development of quantum theory!
Starting around chapter 3, the book tries to explain these basic ideas in quantum theory to a reader who is assumed to have little scientific or mathematical background. Cox and Forshaw try to be reassuring, claiming that if someone is intimidated by the math, they can safely skip it. To their credit, although they refer to calculus and other higher math, the actual math they show is comprehensible to someone who took high school physics. Nevertheless, if you do skip the math … well, you’ll end up reading very little of what’s already a short book.
I fear The Quantum Universe suffers from trying to have its cake and eat it as well. Cox and Forshaw are so invested in not having to explain complex-based trigonometry to a lay audience that they manage to invent an analogy even more complicated than this math! I pulled down my copy of The Illustrated A Brief History of Time and The Universe in a Nutshell, really the best, to see how Stephen Hawking deals with this. He dodges it by just not discussing the math behind it (famously, of course, declaiming in his original introduction that each equation would apparently halve book sales). Yet somehow he manages to discuss the double-slit experiment, quantized electron orbits, and sum-over-histories just fine.
Buried deep in later chapters, Cox and Forshaw explain the difference between the Copenhagen and many-worlds interpretations (though they don’t identify the former as such). And then they take a half-hearted stab and describing the Standard Model but acknowledge it’s going beyond the remit of the book. (Knocking on Heaven’s Door, although laden with a lot of other information and tangents, provides one of the most cogent explanations of the Standard Model I’ve read.)
It’s a shame, because in between the confusing analogies and inexorable unravelling, The Quantum Universe treats the subject of quantum mechanics with wit and a graceful touch. Cox and Forshaw write well together. There is a sense of humour to the descriptions, particularly when they take a stab at the intelligence of drum players (since Cox used to be in a rock band). Despite making assurances about being able to skip the math, they never patronize the reader. This could have been a brilliant introduction to quantum mechanics for the layperson. As it is, while it’s not a total trainwreck, I wouldn’t recommend starting here either.