Einstein’s dislike of quantum indeterminism is well-known. Less well-known are the thought experiments he used to try disprove quantum mechanics. Max Rogers outlines the story of Einstein’s Light Box, arguing that while it ultimately fails, thought experiments are an essential weapon in the scientific toolbox. But, we must be careful when we set them up. Armchair physicists be warned.

Einstein is known to be synonymous with ‘genius’. He had an almost unnerving ability to penetrate reality through intuition, with thought experiments being his preferred weapon of choice. In his youth, Einstein imagined what it was like to chase a light beam, which eventually led him - with more thought experiments along the way - to some of the greatest achievements in scientific history: Special and then General Relativity. His thought experiments were like a scientific magic trick.

Yet Einstein's thought experiments were not confined to classical physics; they also probed quantum mechanics. While he pioneered quantum theory with the photon and introduced the monster of probability with the mathematics predicting electron jumps, Einstein could not accept indeterminacy in physics: he had a palatable distaste for unknowability. Consequently, Einstein used thought experiments to take aim at quantum theory, most famously with the EPR paradox.