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
Symmetry in quantum mechanics act on any four vector A = ("A", "A", "A", "A") and mix the time-like and the space-like components, according to: In relativistic quantum mechanics, wavefunctions are no longer single-component scalar fields, but now 2(2"s" + 1) component spinor fields, where "s" is the spin of the particle. The transformations of these functions in spacetime are given below. Under a proper orthochronous Lorentz transformation in Minkowski space, all one-particle quantum states locally transform under some representation of the Lorentz group: where is a finite-dimensional representation, in other words a dimensional square matrix, and is thought of as a column vector