Schrödinger's cat Schrödinger's cat Schrödinger's cat is a thought experiment, sometimes described as a paradox, devised by Austrian physicist Erwin Schrödinger in 1935. It illustrates what he saw as the problem of the Copenhagen interpretation of quantum mechanics applied to everyday objects. The scenario presents a cat that may be simultaneously both alive and dead, a state known as a quantum superposition, as a result of being linked to a random subatomic event that may or may not occur. The thought experiment is also often featured in theoretical discussions of the interpretations of quantum mechanics. Schrödinger coined the term "Verschränkung" (entanglement) in
Introduction to quantum mechanics an atom that was spun up to spin down: measuring its spin about the horizontal axis collapses its wave function into one of the eigenstates of this measurement, which means it is no longer in an eigenstate of spin about the vertical axis, so can take either value. [[File:Wolfgang Pauli young.jpg|right|thumb|upright|[[Wolfgang Pauli]]]] In 1924, [[Wolfgang Pauli]] proposed a new quantum degree of freedom (or [[quantum number]]), with two possible values, to resolve inconsistencies between observed molecular spectra and the predictions of quantum mechanics. In particular, the [[hydrogen spectrum|spectrum of atomic hydrogen]] had a [[Doublet (physics)|doublet]], or pair of lines differing