Einstein’s Unfinished Revolution: The Search for What Lies Beyond the Quantum

A book that goes beyond the mere reporting of the allegedly stale situation, if not complacency, in discussions of quantum mechanics and its interpretation, at least in the divulgative realm, and breaks through with (mostly personal) hints and examples at what could lie beyond. All of this from an authority that has been musing on these topics for all his career, and has not stopped going at it.

Lee Smolin’s latest book describes the troubles with quantum mechanics (but he used a similar title for his previous books on the problems with string theory) using a structure that anticipates that of Rovelli’s more recent “Helgoland”. In a way, it actually covers a lot of ground that Rovelli covers in that and in “The order of time” (minus his autobiographical and lyrical verbosity). Smolin’s book is much clearer and consistently smooth. It uses a respectful and at the same time bold narrative style, unfortunately without equations and a technical appendix (that would have made it a top book, at the level of Ghirardi’s), to lead the reader from the origin of quantum mechanics to the need to go beyond it. In the “pars destruens”, it covers the fundamentals (uncertainty principle, superposition, entanglement), the Copenhagen interpretation and what he labels anti-realist interpretations, as well as the current main alternatives in the realist camp (pilot wave theory and spontaneous collapse models) and the many-worlds interpretation. This is by now the standard menu of quantum mechanics books, and here Smolin does a pretty good job at highlighting strengths and particularly weaknesses. He is clearly biased towards realism, nonetheless he spends quite some effort looking at Everett’s proposal and its incarnations at Oxford in particular. Smolin mentions many other proposals (including Rovelli’s relational quantum mechanics), and argues that none really holds the ring of truth. Here in fact he diverges from Rovelli, who claims that time does not exist. Smolin starts the “pars construens” by reaching the core of the friction between general relativity and quantum mechanics: wave function collapse is instantaneous and thus requires an inherent frame to define simultaneity, which is forbidden in Einsteinian spacetime. So one has to choose among space and time as to what is fundamental. He vouches for time. And goes over his own work on creating models, inspired by Leibnitz’s monadology, where a set of requirements (“sufficient reason”) articulate a relational view where causality, energy and momentum flow, and entanglement are basic and let space and quantum mechanics emerge as granular levels and as maximization of variety within order, respectively. Smolin knows these creations may turn out to be wrong, but he is excited nonetheless because these models (and others he mentions) are testable, and so could be falsified. That’s refreshing, and one is left with a real sense of ongoing quest, after decades of dismissal in academic circles, in foundations of physics and particularly the quantum (for which he actually thanks also quantum information theory and its application to quantum computing).
The book concludes with a chapter of “notes to self” with reflections of personal and general interest, ultimately optimistic towards a renewed scientific dialogue towards a new theory.