What is Real? The Unfinished Quest for the Meaning of Quantum Physics: Book Review

Adam Becker, What is Real? The Unfinished Quest for the Meaning of Quantum Physics, London: John Murray, 2018.

This book is, at heart, a history of one literally earth-shaking event in the history of physics and its ongoing implications. It traces transformation from one way of thinking about matter — the “stuff” of the physical world  — to quite another. “Newtonian” physics (mass, speed, gravity, acceleration, momentum, etc.) established a set of principles that did seem to explain the physical world — in a word, matter — pretty well to just about everyone.  From roughly the turn of the twentieth century, though, more and more questions arose about “what is real?” culminating in a set of mathematical principles that apparently don’t explain anything much to anybody, but rather describe some deeply strange things, while seeming themselves to demand explanation. Gradually a new vocabulary arose for speaking about matter, with particles — dozens of them — entanglements, spin, inconceivable distances and time measured in light years.  There is something deeply troubling about it all. Perhaps it’s simply the idea that the title could be a question. We’re OK with fuzziness in psychology and sociology, even perhaps in politics and business.  But science is supposed to know.

The book is carefully-researched and scrupulously fair to a very large number of very committed scientists with real lives, beliefs, strengths, failings, and very human emotions. Many names are familiar — Einstein, Bohr, Heisenberg, Schrödinger and more. A great deal of the story consists of meetings, correspondence, publications, conversations — with only a few actual experiments, among them the one that culminated in the development of the atom bomb.  To me, at least, this may have been the single most sobering thought — namely that such a vast transformation in the most widely accepted (and, on the whole, respected) model of matter, of reality, would occur in language — and I don’t mean mathematical language, I mean first German, then English and French and Italian, then hundreds of them — human languages, “natural” languages.

I can’t quite shake the idea that this is what Niels Bohr meant by his insistence — which remains unexplained today — that the findings of quantum research “must be expressed in the language of classical physics”.  Bohr is a principle figure in this story: the Danish physicist widely credited with having first established the fundamental principles governing the way “quanta” — discreet, regular quantities of energy — affect the behaviour of particles. Becker has ample evidence of Bohr’s struggles with language.  He was, by all accounts, including his own, painfully inarticulate, to the point where colleagues and even students simply did not understand what he was trying to say — and to a large extent still don’t.  In this respect he was a stunning contrast to Einstein, who peppered both German and English with resonant, pithy, memorable phrases that express thoughts any one of us might share, i.e. “God does not play dice with the universe” (a conviction about ultimate order, meaning) or  “spooky action at a distance,” (a reluctance to embrace the idea of particles becoming entangled with one another). The phrases condense things, also acknowledge completely human responses, responses any one of us might have. Ultimately, though they mainly express wonder; they do not resolve things.

Despite the literally incredible findings in contemporary physics, things being in two places at once, things whose behaviour can only be called vague, I’ve always assumed that there was some at least general agreement, at least among physicists, about the nature of material reality, that is, about matter.  Becker’s book more than suggests that there is no such agreement. Many people refer to The Copenhagen Agreement, or Convention, after the city where the famous Solvay conference (1923) took place. There, a glittering array of accomplished physicists spoke — in general sessions and private conversations.  Correspondence preceded and followed the event. But the idea that they arrived at an agreement about the many open issues — just seems to be something like a myth, a story that “explains” a state of affairs without necessarily providing a consistent or satisfying account of the details.  Writers — and Becker is by no means the only one — invariably insist that there never was any such agreement.  There was a kind of unspoken agreement not to quarrel about the reality of matter:  research continues without any such agreement because reality can be described mathematically with great precision. The arguments, it seems, were and still are verbal.  It is writers and speakers and readers who still worry about it, who want matter to be comprehensible in terms they can grasp — which may be, simply, in language.  I wonder whether Bohr was among us, if that was what he meant by “the language of classical physics,” words like “momentum” and “speed” and “acceleration”, words that may refer to difficult concepts, but remain comprehensible — to humans. Becker is a rare physicist and writer who continues to be deeply concerned about the question “What is Real?”