Schrödinger's cat

by 1972 in reference to the thought experiment proposed in 1935 by Austrian-born physicist Erwin Schrödinger (1887-1961) in correspondence with Albert Einstein about quantum mechanics. Schrödinger was pointing out a problem in the then-prevailing interpretation of the science. Einstein had written, as an example, about an unstable keg of gunpowder that will in some quantum sense exist in both exploded and unexploded states. To point out the flaw Schrödinger wrote "One can even set up quite ridiculous cases," and described the cat situation, in which the animal is both dead and alive until its state has been observed.