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Hugh Everett III

Hugh Everett III was an American physicist who, as a doctoral student of John Wheeler at Princeton, proposed the relative-state formulation of quantum mechanics…

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Also known as Hugh Everett

1930 – 1982 · Washington, D.C.; Princeton, New Jersey; Virginia

Traditions: American

Hugh Everett III was an American physicist who, as a doctoral student of John Wheeler at Princeton, proposed the relative-state formulation of quantum mechanics in 1957. He dropped the assumption that measurement collapses the wave function and treated observer and system as one quantum whole. Everett left academic physics for defence operations research, and his idea gained wide attention only later, when Bryce DeWitt popularised it as the many-worlds interpretation.

Key ideas

  • The universal wave function always evolves smoothly; there is no separate collapse on measurement.
  • After a measurement, each state of the observer is correlated with a corresponding state of the system: a relative state.
  • The appearance of single definite outcomes is explained by this branching structure of correlations.
  • How probabilities fit a theory in which every outcome occurs remains a central and debated problem for his view.

Major works

  • "'Relative State' Formulation of Quantum Mechanics" (1957, Reviews of Modern Physics)
  • "The Theory of the Universal Wave Function" (long version of his thesis, published 1973 in DeWitt and Graham, eds., The Many-Worlds Interpretation of Quantum Mechanics)

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