Physics. Is quantum mechanics tried, true, wildly successful, and wrong?

Antony Valentini has never been happy with quantum mechanics. Sure, it’s the most powerful and accurate scientific theory ever devised. Yes, its bizarre predictions about the behavior of atoms and all other particles have been confirmed many times over with multi-decimalplace exactitude. True, technologies derived from quantum mechanics may account for 30% of the gross national product of the United States. So what’s not to like? Valentini, a theoretical physicist at Imperial College London (ICL) and the co-author of a forthcoming book on the early history of quantum mechanics, believes that shortly after the theory’s birth some 80 years ago, a cadre of influential scientists led quantum physics down a philosophical blind alley. As a result of that wrong turn, Valentini says, the f ield wound up burdened with paradoxical dualities, inexplicable long-distance connections between particles, and a pragmatic “shut up and calculate” mentality that stifled attempts to probe what it all means. But there is an alternative, Valentini says: a long-abandoned “road not taken” that could get physics back on track. And unlike other proposed remedies to quantum weirdness, he adds, there’s a possible experiment to test whether this one is right. “There isn’t a more insightful or knowledgeable critic in the whole field of quantum theory,” says Lee Smolin, a theoretical physicist at the Perimeter Institute for Theoretical Physics in Waterloo, Canada. Smolin, who researches a subfield known as quantum gravity, has long held that current quantum theory is incomplete at best. In a book to be published later this year by Cambridge University Press, Valentini and coauthor Guido Bacciagaluppi, a philosopher of physics at the University of Aberdeen in the United Kingdom, reassess a pivotal and contentious meeting at which 29 physics luminaries—including Louis de Broglie, Niels Bohr, Werner Heisenberg, Erwin Schrödinger, and Albert Einstein—butted brains over how to make sense of quantum theory. The book, Quantum Theory at the Crossroads, includes the first English translation of the proceedings of the historic 1927 Solvay conference. The gathering was the fifth in an ongoing series of invitation-only conferences in Brussels, Belgium, launched in 1911 by the Belgian industrialist Ernest Solvay. At the meeting, blandly titled “Electrons and Photons,” attendees grappled with issues that