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
Two-body Dirac equations The four-vectors formula_120 and formula_121 have only three independent components since The similarity to the three-dimensional structure of the nonrelativistic Schrödinger equation can be made more explicit by writing the equation in the c.m. frame in which Comparison of the resultant form with the time independent Schr\"{o}dinger equation makes this similarity explicit. A plausible structure for the quasipotential formula_83 can be found by observing that the one-body Klein-Gordon equation formula_127 takes the form formula_128 when one introduces a scalar interaction and timelike vector interaction via formula_129and formula_130. In the two-body case, separate classical and quantum field theory arguments show that