Interpretations of Quantum Mechanics - Comparison of Interpretations

Comparison of Interpretations

The most common interpretations are summarized in the table below. The values shown in the cells of the table are not without controversy, for the precise meanings of some of the concepts involved are unclear and, in fact, are themselves at the center of the controversy surrounding the given interpretation.

No experimental evidence exists that distinguishes among these interpretations. To that extent, the physical theory stands, and is consistent with itself and with reality; difficulties arise only when one attempts to "interpret" the theory. Nevertheless, designing experiments which would test the various interpretations is the subject of active research.

Most of these interpretations have variants. For example, it is difficult to get a precise definition of the Copenhagen interpretation as it was developed and argued about by many people.

Interpretation Author(s) Deterministic? Wavefunction
real?		 Unique
history?		 Hidden
variables?		 Collapsing
wavefunctions?		 Observer
role?		 Local? Counterfactual definiteness?
Ensemble interpretation Max Born, 1926 Agnostic No Yes Agnostic No None No No
Copenhagen interpretation Niels Bohr, Werner Heisenberg, 1927 No No1 Yes No Yes2 Causal No No
de Broglie–Bohm theory Louis de Broglie, 1927, David Bohm, 1952 Yes Yes3 Yes4 Yes No None No Yes
von Neumann interpretation von Neumann, 1932, Wheeler, Wigner No Yes Yes No Yes Causal No No
Quantum logic Garrett Birkhoff, 1936 Agnostic Agnostic Yes5 No No Interpretational6 Agnostic No
Many-worlds interpretation Hugh Everett, 1957 Yes Yes No No No None Yes No
Popper's interpretation Karl Popper, 1957 No Yes Yes Yes No None Yes Yes13
Time-symmetric theories Yakir Aharonov, 1964 Yes Yes Yes Yes No No Yes No
Stochastic interpretation Edward Nelson, 1966 No No Yes No No None No No
Many-minds interpretation H. Dieter Zeh, 1970 Yes Yes No No No Interpretational7 Yes No
Consistent histories Robert B. Griffiths, 1984 Agnostic8 Agnostic8 No No No Interpretational6 Yes No
Objective collapse theories Ghirardi–Rimini–Weber, 1986, Penrose interpretation, 1989 No Yes Yes No Yes None No No
Transactional interpretation John G. Cramer, 1986 No Yes Yes No Yes9 None No Yes14
Relational interpretation Carlo Rovelli, 1994 No No Agnostic10 No Yes11 Intrinsic12 Yes No
  • 1 According to Bohr, the concept of a physical state independent of the conditions of its experimental observation does not have a well-defined meaning. According to Heisenberg the wavefunction represents a probability, but not an objective reality itself in space and time.
  • 2 According to the Copenhagen interpretation, the wavefunction collapses when a measurement is performed.
  • 3 Both particle guiding wavefunction are real.
  • 4 Unique particle history, but multiple wave histories.
  • 5 But quantum logic is more limited in applicability than Coherent Histories.
  • 6 Quantum mechanics is regarded as a way of predicting observations, or a theory of measurement.
  • 7 Observers separate the universal wavefunction into orthogonal sets of experiences.
  • 8 If wavefunction is real then this becomes the many-worlds interpretation. If wavefunction less than real, but more than just information, then Zurek calls this the "existential interpretation".
  • 9 In the TI the collapse of the state vector is interpreted as the completion of the transaction between emitter and absorber.
  • 10 Comparing histories between systems in this interpretation has no well-defined meaning.
  • 11 Any physical interaction is treated as a collapse event relative to the systems involved, not just macroscopic or conscious observers.
  • 12 The state of the system is observer-dependent, i.e., the state is specific to the reference frame of the observer.
  • 13 Caused by the fact that Popper holds both CFD and locality to be true, it is under dispute whether Popper's interpretation can really be considered an interpretation of Quantum Mechanics (which is what Popper claimed) or whether it must be considered a modification of Quantum Mechanics (which is what many Physicists claim), and, in case of the latter, if this modification has been empirically refuted or not. Popper exchanged many long letters with Einstein, Bell etc. about the issue.
  • 14 The transactional interpretation is explicitly non-local.

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