Schrödinger's cat regard the "alive and dead" cat superposition as quite real. Intended as a critique of the Copenhagen interpretation (the prevailing orthodoxy in 1935), the Schrödinger's cat thought experiment remains a defining touchstone for modern interpretations of quantum mechanics. Physicists often use the way each interpretation deals with Schrödinger's cat as a way of illustrating and comparing the particular features, strengths, and weaknesses of each interpretation. Schrödinger wrote: Schrödinger's famous thought experiment poses the question, ""when" does a quantum system stop existing as a superposition of states and become one or the other?" (More technically, when does the actual quantum state
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