In 1935 Austrian physicist Erwin Schrodinger (1887-1961) published a three-part essay on The Present Situation in Quantum Mechanics in which his famous Schrodinger's cat paradox appears. This was a thought experiment where a cat in a closed box either lived or died according to whether a quantum event occurred. The paradox was that both universes, one with a dead cat and one with a live one, seemed to exist in parallel until an observer opened the box.