Einstein, however, persistently argued that the Copenhagen interpretation was incomplete. Sifting through the history, Becker shows how Bohr, as an anti-realist, brought to his side many rising physicists, including Heisenberg, Wolfgang Pauli and Max Born. In the classical world of billiard balls, projectiles and apples falling from trees, they were never problems. (Einstein called this “spooky action at a distance”.)īecker explains how these observations challenge locality, causality and determinism. For example, two particles might have opposite spins, no matter how far apart they are: if you measure one to be spin up, you instantly know that the other is spin down. Third, Bohr argued that we could have only probabilistic knowledge of a system: in Schrödinger’s thought experiment, a cat in a box is both dead and alive until it is seen. Second, Heisenberg showed that uncertainty, for instance about a particle’s position and momentum, is hard-wired into physics. According to Bohr, a system behaves as a wave or a particle depending on context, but you cannot predict which it will do. First was wave–particle duality, in which light can act as particles and particles such as electrons interfere like light waves. Quantum phenomena were phenomenally baffling to many. Years later, he added a gloss: “What we call science has the sole purpose of determining what is.” Suddenly, scientific realism - the idea that confirmed scientific theories roughly reflect reality - was at stake. Whereas Bohr proposed that entities (such as electrons) had only probabilities if they weren’t observed, Einstein argued that they had independent reality, prompting his famous claim that “God does not play dice”.

Here, the disagreements between Bohr, Einstein and others, including Erwin Schrödinger and Louis de Broglie, came to a head. Had events played out differently in the 1920s, he asserts, our view of physics might be very different.īecker lingers on the 1927 Solvay Conference in Brussels, where 29 brilliant scientists gathered to discuss the fledgling quantum theory. Showing that the evolution of science is affected by historical events - including sociological, cultural, political and economic factors - he explores alternative explanations. Becker argues that trying to parse how this interpretation reflects the world we live in is an exercise in opacity. Propounded by Bohr and Werner Heisenberg in the 1920s, this theory holds that physical systems have only probabilities, rather than specific properties, until they’re measured. Adam Becker, a science writer and astrophysicist, explores this tangled tale in What Is Real?.īecker questions the hegemony of the Copenhagen interpretation of quantum mechanics. It posed a challenge to the very nature of science, and arguably continues to do so, by severely straining the relationship between theory and the nature of reality. Quantum theory emerged - partly in heated clashes between Albert Einstein and Niels Bohr. What Is Real?: The Unfinished Quest for the Meaning of Quantum Physics Adam Becker Basic: 2018.Īll hell broke loose in physics some 90 years ago.

Credit: Emilio Segre Visual Archives/AIP/SPL Niels Bohr (left) with Albert Einstein in the late 1920s, when quantum mechanics was in its infancy.

Albert einstein atomic theory