Book review: Beyond Weird: Why Everything You Thought You Knew About Quantum Mechanics is Different by Philip Ball


(My review of the above book just appeared in the March 2019 issue of the American Journal of Physics (vol. 87, issue 4, p.319). You can access it here but I give the review below.)

A major problem with quantum mechanics is that the dominant Copenhagen interpretation is not conducive to providing visual images of what is going on. With special and general relativity, the initially unsettling ideas that time and distance are not invariants but depend upon the state of motion of the observer and that space can be warped by the presence of mass and energy have gone mainstream. Not so with quantum mechanics. Although of the same vintage as relativity, quantum mechanics has continued to greatly perplex people because it undermines the realist position that other theories, including relativity, take for granted, of a world existing independent of the observer, whose features we can discover by making observations. The denial of this made even Einstein uneasy.

This has resulted in two approaches to the subject. One is a hard-nosed attitude that argues that scientific theories are not obliged to provide us with visualizations of processes that take place beyond the reach of our sensory capabilities. Instead, we should simply use the mathematical machinery of quantum mechanics to calculate quantities of interest that can be measured, something that it has been remarkably successful in doing. P. A. M. Dirac’s words that “the main object of physical science is not the provision of pictures, but is the formulation of laws governing phenomena and the application of these laws to the discovery of new phenomena” are often quoted to support this view. However, such a level of operational expertise and understanding is only available to those willing to spend many years studying the subject.

We also have a proliferation of books and articles that take the alternative approach that strives to provide the general public with some kind of understanding of what is “really” going on using metaphors and analogies and no mathematics. Unfortunately, some authors who write in this vein have exaggerated the strange aspects in order to make all manner of metaphysical claims that have little basis in the actual theory.

Ball’s book belongs in the second category but seeks to correct popular misconceptions that have emerged from such efforts. His argument is that quantum mechanics is strange but not always in the way that people think and that recent experiments have provided insight into what had earlier been purely intellectual speculations about what it all means.

His book consists of two parts. He starts with familiar quotations from Niels Bohr (“Anyone who is not shocked by quantum theory has not understood it”) and Richard Feynman (“I think I can safely say that nobody understands quantum mechanics”) which emphasize the strangeness of quantum mechanics. He tries to demystify what we might call “quantum mechanics greatest hits”: Heisenberg’s Uncertainty Principle, Schrödinger’s cat and the superposition of states, wave-particle duality, measurement and wave function collapse, the double-slit experiment, non-locality, the EPR paradox, and Bell’s theorem. I would venture that most physicists would not find much that is new in this largely historical overview.

In the second part, Ball goes into more recent areas of research which are less familiar and would be of interest even to professional physicists. Ball argues that ultimately quantum mechanics is not a theory about how tiny particles behave but instead comprises a set of rules for representing and manipulating information (a notoriously slippery concept) and the causative influences involved in a system and about what is and is not knowable about it. He uses that framework to discuss recent advances in entanglement, quantum cryptography, quantum teleportation, quantum computing, and the Many Worlds interpretation and other alternatives to the Copenhagen interpretation.

For example, he presents the view that the measurement process (in which a superposition of quantum states interacts with a classical macroscopic detector) does not mean that the coherent entangled wave function has instantaneously collapsed but that the initial state rapidly spread its entanglement to the detector elements and the rest of the environment, a process known as decoherence. This imprints information about the initial quantum state onto its environment, but since detectors are able to reflect only part of that information, it appears as if the wave function collapsed.

There are some minor annoyances. The subtitle uses a familiar internet clickbait trope of making a provocative but unjustifiable sweeping claim. The initial reaction of this reviewer was “Really? Everything? How do you know what I know?” If readers are willing to get past that initial negative reaction, they will find that Ball writes well and treats his subject seriously and not sensationally. Another problem is the lack of in-text citations to the bibliography. Their absence hinders attempts to read more deeply on the topics, and the skimpy notes section is of no help. A third irritant that could have been easily avoided is that although the book is split up into chapters, there are no chapter numbers and no table of contents. If one wants to refer to material elsewhere in the book, one has to flip through the pages to find the relevant section. It makes even this review less helpful because I cannot point readers to the chapters where specific topics are discussed.

As with all such books that seek to explain this essentially mathematical theory without mathematics, the result is a series of assertions that readers have to simply accept at face value and can result in some of them rapidly feeling out of their depth. But all in all, this is a worthwhile addition to the many books that seek to make quantum mechanics understandable.

Comments

  1. raym says

    Mano… for the past year or three I have been trying to wrap my head around quantum computing, with at least a little success. However, one thing that eludes me is the concept of polarisation. In the more practical world I understand it well enough in relation to, say, electromagnetic radiation, but at the quantum level I am forced to ask “polarisation with respect to what, exactly?” Can you help? Does my question even have meaning?

  2. Pierce R. Butler says

    Dunno ’bout the quanto-mecho stuff, but will happily vouch for Ball’s talents as a wide-ranging history-of-science writer (The Devil’s Doctor: Paracelsus and the World of Renaissance Magic and Science; Serving the Reich: the Struggle for the Soul of Physics Under Hitler; etc.).

  3. Rob Grigjanis says

    raym @1: Fundamental particles have a property called spin, which is intrinsic angular momentum. They can have (in units of the reduced Planck constant) the values 0 (e.g. Higgs boson), 1/2 (e.g. electron), or 1 (e.g. W vector boson). And if the graviton exists, it has spin 2.

    If you measure the spin of an electron along any axis, it can only have two possible values (or polarizations, if you like): +1/2, or -1/2. Further, the electron can be prepared in a coherent superposition of the +1/2 and -1/2 states, so its quantum state can be written

    α|+1/2> + β|-1/2>

    where α and β are complex numbers satisfying |α|² + |β|² = 1

    These properties are exactly what you need for a qubit.

  4. consciousness razor says

    Have you read Adam Becker’s What is Real, and if so what did you think? I watched this google talk from last year. Nothing that others haven’t covered before, but it was good. He definitely covered an impressive amount of ground in such a short time. And people seem to like his writing, but these are random internet people and I can never tell what to make of that.

  5. Mano Singham says

    consciousness razor @#4,

    I have not read Becker’s book but coincidentally a review of it appeared in the same issue of the same journal as my review, right next to mine in fact. You can read the review here. It was a little harsh, suggesting that Becker writes well but that the content was not sound.

    My forthcoming book addresses some of the issues of interpretations of quantum mechanics that Becker seems to do. but not as its main theme. It is used as an example of how much of scientific history does not correspond all that well with what actually happened.

  6. consciousness razor says

    Thanks.
    First thought as I was reading that review: “Quantum has no king. Quantum needs no king.”
    And then a bit later it was: “One does not simply walk into Niels Bohr.”
    (Apologies to Boromir.)

  7. Jenora Feuer says

    I’ll admit my first real exposure to some of this was Nick Herbert’s Quantum Reality, which was definitely written for an ‘educated layman’ sort of audience, and which (in my educated layman’s opinion) I thought did a decent job. Amongst other things, it went ‘here are eight different interpretations of what is really going on that are all consistent with what we actually witness, and good luck figuring out any way to make any sort of experiment to distinguish them’ and then went into Bell’s Theorem and how that affected various interpretations.

    That said, the book is from 1985, and at least some things have changed since then.

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