The universal wavefunction or the wavefunction of the universe is the
wavefunction
In quantum physics, a wave function (or wavefunction) is a mathematical description of the quantum state of an isolated quantum system. The most common symbols for a wave function are the Greek letters and (lower-case and capital psi (letter) ...
or
quantum state
In quantum physics, a quantum state is a mathematical entity that embodies the knowledge of a quantum system. Quantum mechanics specifies the construction, evolution, and measurement of a quantum state. The result is a prediction for the system ...
of the entire
universe
The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...
. It is regarded as the basic physical entity in the
many-worlds interpretation
The many-worlds interpretation (MWI) is an interpretation of quantum mechanics that asserts that the universal wavefunction is Philosophical realism, objectively real, and that there is no wave function collapse. This implies that all Possible ...
of
quantum mechanics
Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is ...
,
Hugh Everett
Hugh Everett III (; November 11, 1930 – July 19, 1982) was an American physicist who proposed the relative state interpretation of quantum mechanics. This influential approach later became the basis of the many-worlds interpretation (MWI). Ev ...
, 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 Wavefunction'' and finds applications in
quantum cosmology. It evolves deterministically according to a wave equation.
The concept of universal wavefunction was introduced by
Hugh Everett
Hugh Everett III (; November 11, 1930 – July 19, 1982) was an American physicist who proposed the relative state interpretation of quantum mechanics. This influential approach later became the basis of the many-worlds interpretation (MWI). Ev ...
in his 1956 PhD thesis draft ''The Theory of the Universal Wave Function''. It later received investigation from
James Hartle
James Burkett Hartle (August 17, 1939 – May 17, 2023) was an American theoretical physicist. He joined the faculty of the University of California, Santa Barbara in 1966, and was a member of the external faculty of the Santa Fe Institute. Hart ...
and
Stephen Hawking
Stephen William Hawking (8January 194214March 2018) was an English theoretical physics, theoretical physicist, cosmologist, and author who was director of research at the Centre for Theoretical Cosmology at the University of Cambridge. Between ...
[ 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
The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models based on the Big Bang concept explain a broad range of phenomena, including th ...
cosmology.
Role of observers
Hugh Everett
Hugh Everett III (; November 11, 1930 – July 19, 1982) was an American physicist who proposed the relative state interpretation of quantum mechanics. This influential approach later became the basis of the many-worlds interpretation (MWI). Ev ...
's universal wavefunction supports the idea that observed and observer are all mixed together:
Eugene Wigner
Eugene Paul Wigner (, ; November 17, 1902 – January 1, 1995) was a Hungarian-American theoretical physicist who also contributed to mathematical physics. He received the Nobel Prize in Physics in 1963 "for his contributions to the theory of th ...
and
John Archibald Wheeler
John Archibald Wheeler (July 9, 1911April 13, 2008) was an American theoretical physicist. He was largely responsible for reviving interest in general relativity in the United States after World War II. Wheeler also worked with Niels Bohr to e ...
take issue with this stance. Wigner wrote:
Wheeler wrote:
See also
*
Heisenberg cut
References
{{Reflist
Quantum measurement