AT ITS deepest level, nature is random and unpredictable. That, most physicists would say, is the unavoidable lesson of quantum theory. Try to track the location of an electron and you’ll find only a probability that it is here or there. Measure the spin of an atom and all you get is a 50:50 chance that it is up or down. Watch a photon hit a glass plate and it will either pass through or be reflected, but it’s impossible to know which without measuring it.

Where does this randomness come from? Before quantum theory, physicists could believe in determinism, the idea of a world unfolding with precise mathematical certainty. Since then, however, the weird probabilistic behaviour of the quantum world has rudely intruded, and the mainstream view is that this uncertainty is a fundamental feature of everything from alpha particles to Z bosons. Indeed, most quantum researchers celebrate the notion that pure chance lies at the foundations of the universe.

However, a sizeable minority of physicists have long been pushing entirely the opposite view. They remain unconvinced that quantum theory depends on pure chance, and they shun the philosophical contortions of quantum weirdness. The world is not inherently random, they say, it only appears that way. Their response has been to develop quantum models that are deterministic, and that describe a world that has “objective” properties, whether or not we measure them. The problem is that such models have had flaws that many physicists consider fatal, such as inconsistencies with established theories.

Until now, that is. A series of recent papers show that the idea of a deterministic and …