Universal wavefunction

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The Universal Wavefunction is a term introduced by Hugh Everett in his Princeton PhD Thesis[1], entitled The Theory of the Universal Wavefunction and forms a core concept in the relative state interpretation[2][3] or many-worlds interpretation[4][5] of quantum mechanics.

The thesis introduction reads:

Since the universal validity of the state function description is asserted, one can regard the state functions themselves as the fundamental entities, and one can even consider the state function of the entire universe. In this sense this theory can be called the theory of the "universal wavefunction," since all of physics is presumed to follow from this function alone.

The universal wavefunction is the wavefunction or quantum state of the totality of existence, regarded as the "basic physical entity"[6] or "the fundamental entity, obeying at all times a determinstic wave equation"[7].

[edit] Criticism

Ray Streater writes on his "lost causes" web page:

The idea of the wave-function of the universe is meaningless; we do not even know what variables it is supposed to be a function of. [...] We find the laws of Nature by reproducible experiments. The theory needs a cut, between the observer and the system, and the details of the apparatus should not appear in the theory of the system.

Hugh Everett's 'response'[8].

If we try to limit the applicability so as to exclude the measuring apparatus, or in general systems of macroscopic size, we are faced with the difficulty of sharply defining the region of validity. For what n might a group of n particles be construed as forming a measuring device so that the quantum description fails? And to draw the line human or animal observers [...] does violence to the so-called principle of psycho-physical parallelism.

[edit] References

  1. ^ Bryce Seligman DeWitt, R. Neill Graham, eds, The Many-Worlds Interpretation of Quantum Mechanics, Princeton Series in Physics, Princeton University Press (1973), ISBN 0-691-08131-X Contains Everett's thesis: The Theory of the Universal Wavefunction, pp 3-140.
  2. ^ 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 Wavefunction
  3. ^ John Archibald Wheeler, Assessment of Everett's "Relative State Formulation of Quantum Theory", Reviews of Modern Physics, vol 29, (1957) pp 463-465
  4. ^ Bryce Seligman DeWitt, Quantum Mechanics and Reality, Physics Today,23(9) pp 30-40 (1970) also April 1971 letters followup
  5. ^ Bryce Seligman DeWitt, The Many-Universes Interpretation of Quantum Mechanics, Proceedings of the International School of Physics "Enrico Fermi" Course IL: Foundations of Quantum Mechanics, Academic Press (1972)
  6. ^ Everett 1957, section 3, 2nd paragraph, 1st sentence
  7. ^ Everett [1956]1973, "Theory of the Universal Wavefunction", chapter 6 (e)
  8. ^ Everett [1956]1973, "Theory of the Universal Wavefunction", introduction

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