The universal wave function or the wave function of the universe is the wavefunction or quantum state of the entire universe.Everett 1973, "Theory of the Universal Wavefunction", introduction, pg 8–9 It is regarded as the basic physical entityEverett 1957, section 3, 2nd paragraph, 1st sentence. in the many-worlds interpretation of quantum mechanics,Hugh Everett, Relative State Formulation of Quantum Mechanics, Reviews of Modern Physics vol 29, (1957) pp 454–462. An abridged summary of The Theory of the Universal WavefunctionJohn Archibald Wheeler, Assessment of Everett's "Relative State Formulation of Quantum Theory", Reviews of Modern Physics, vol 29, (1957) pp 463–465Bryce Seligman DeWitt, Quantum Mechanics and Reality, Physics Today,23(9) pp 30–40 (1970) also April 1971 letters followupBryce Seligman DeWitt, The Many-Universes Interpretation of Quantum Mechanics, Proceedings of the International School of Physics "Enrico Fermi" Coursu IL: Foundations of Quantum Mechanics, Academic Press (1972) and finds applications in quantum cosmology. It evolves deterministically according to a wave equation.Everett 1973, "Theory of the Universal Wavefunction", chapter 6 (e)
The concept of universal wave function was introduced by Hugh Everett III in his 1956 PhD thesis draft The Theory of the Universal Wave Function.Bryce Seligman DeWitt, R. Neill Graham, eds, The Many-Worlds Interpretation of Quantum Mechanics, Princeton Series in Physics, Princeton University Press (1973), Contains the reprint of Everett's thesis: The Theory of the Universal Wave Function, pp 3–140. It later received investigation from James Hartle and Stephen Hawking,Stephen W Hawking, James B Hartle "The Wave Function of the Universe," Physical Review D, vol 28, (1983) pp 2960–2975 who derived the Hartle–Hawking solution to the Wheeler–DeWitt equation to explain the initial conditions of the Big Bang cosmology.
Role of observers Hugh Everett's universal wavefunction supports the idea that observed and observer are all mixed together:
Eugene Wigner and John Archibald Wheeler take issue with this stance. Wigner wrote:
Wheeler wrote:
See also Heisenberg cut Wave function collapse
References