An IAS teatime conversation in 1935 introduces an ongoing debate over quantum physics.

"Einstein Attacks Quantum Theory” read the New York Times headline of May 4, 1935. The article continued:

Professor Albert Einstein will attack science’s important theory of quantum mechanics, a theory of which he was a sort of grandfather. He concludes that while it is “correct” it is not “complete.” With two colleagues at the Institute for Advanced Study here, the noted scientist is about to report to the American Physical Society what is wrong with the theory of quantum mechanics. The quantum theory with which science predicts with some success inter-atomic happenings does not meet the requirements for a satisfactory physical theory, Professor Einstein will report in a joint paper with Dr. Boris Podolsky and Dr. N. Rosen.

Two years after he joined the Institute’s Faculty, Einstein coauthored the referenced paper “Can Quantum-Mechanical Description of Physical Reality be Considered Complete?” with Podolsky and Rosen, generally referred to as EPR. Einstein had recruited Podolsky and Rosen as Members of the Institute in 1934. In a letter dated November 10, 1933, to Abraham Flexner, the Institute’s founding Director, Einstein described Podolsky as “one of the most brilliant of the younger men who has worked and published with [Paul] Dirac.”

Can the weird quantum mechanical property of entanglement give rise to wormholes connecting far away regions in space?

In 1935, Albert Einstein and collaborators wrote two papers at the Institute for Advanced Study. One was on quantum mechanics [1] and the other was on black holes [2]. The paper on quantum mechanics is very famous and influential. It pointed out a feature of quantum mechanics that deeply troubled Einstein. The paper on black holes pointed out an interesting aspect of a black hole solution with no matter, where the solution looks like a wormhole connecting regions of spacetime that are far away. Though these papers seemed to be on two completely disconnected subjects, recent research has suggested that they are closely connected.

Einstein’s theory of general relativity tells us that spacetime is dynamical. Spacetime is similar to a rubber sheet that can be deformed by the presence of matter. A very drastic deformation of spacetime is the formation of a black hole. When there is a large amount of matter concentrated in a small enough region of space, this can collapse in an irreversible fashion. For example, if we filled a sphere the size of the solar system with air, it would collapse into a black hole. When a black hole forms, we can define an imaginary surface called “the horizon”; it separates the region of spacetime that can send signals to the exterior from the region that cannot. If an astronaut crosses the horizon, she can never come back out. She does not feel anything special as she crosses the horizon. However, once she crosses, she will be inevitably crushed by the force of gravity into a region called “the singularity” (Figure 1a).