Along with Podolsky and Rosen he formulated one of the original quantum thought experiments to challenge the accepted conventions: https://en.m.wikipedia.org/wi

Along with Podolsky and Rosen he formulated one of the original quantum thought experiments to challenge the accepted conventions: https://en.m.wikipedia.org/wiki/Einstein%E2%80%93Podolsky%E2%80%93Rosen_paradox https://en.m.wikipedia.org/wiki/Einstein%E2%80%93Podolsky%E2... This in turn inspired Bell's theorem, and eventually quantum information theory.