After formulating the theory of general relativity, Albert Einstein had shown that photons have momentum and that electrons and other subatomic particles display characteristics of both waves and particles. These discoveries helped form the quantum theories of Werner Heisenberg and Niels Bohr, who proposed that this wave-particle duality exhibited a randomness that is affected by the observer himself. Thereby, the more precisely the particle’s position is determined, the less precisely its momentum is known; the more precisely the momentum of the particle, the less precisely its position is known.
Einstein could never accept the random nature of quantum mechanics and conducted a series of thought experiments to disprove this theory. Bohr would counter and attempt to prove him wrong. Albert Einstein and Niels Bohr held a long-standing verbal jousting match about quantum theory during the 1920s and 30s. Bohr responded to Einstein’s famous quip, “God does not play dice,” by saying “Einstein, stop telling God what to do.”