User:TheLastWordSword/Interpretations of quantum mechanics

Tabular comparison

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?	Universal wavefunction exists?
Ensemble interpretation	Max Born, 1926	Agnostic	No	Yes	Agnostic	No	No	Agnostic	No	No
Hydrodynamic Interpretation	Erwin Madelung, 1926	Yes	Yes	Yes	Yes	No	No	No	Yes	Yes
Copenhagen interpretation	Niels Bohr, Werner Heisenberg, 1927	No	No1	Yes	No	Yes2	Causal	Agnostic	No	No
de Broglie–Bohm theory	Louis de Broglie, 1927, David Bohm, 1952	Yes	Yes3	Yes4	Yes	No	No	No17	Yes	Yes
von Neumann interpretation	John von Neumann, 1932, John Archibald Wheeler, Eugene Wigner	No	Yes	Yes	No	Yes	Causal	No	No	Yes
Quantum logic	Garrett Birkhoff, 1936	Agnostic	Agnostic	Yes5	No	No	Interpretational6	Agnostic	No	No
Time-symmetric theories	Olivier Costa de Beauregard, 1947, Satosi Watanabe, 1955	Yes	Yes	Yes	Yes	No	No	Yes	No	Yes
Many-worlds interpretation	Hugh Everett, 1957	Yes	Yes	No	No	No	No	Yes	No	Yes
Popper's interpretation	Karl Popper, 1957	No	Yes	Yes	Yes	No	No	(Yes)13	Yes	No
Stochastic mechanics	Edward Nelson, 1966	No	No	Yes	Yes16	No	No	No	Only for position 16	No
Many-minds interpretation	H. Dieter Zeh, 1970	Yes	Yes	No	No	No	Interpretational7	Yes	No	Yes
Consistent histories	Robert B. Griffiths, 1984	Agnostic8	Agnostic8	No	No	No	Interpretational6	Yes	No	No
Objective collapse theories	Ghirardi–Rimini–Weber, 1986, Penrose interpretation, 1989	No	Yes	Yes	No	Yes	No	No	No	No
Transactional interpretation	John G. Cramer, 1986	No	Yes	Yes	No	Yes9	No	No14	Yes	No
Relational interpretation	Carlo Rovelli, 1994	Agnostic	No	Agnostic10	No	Yes11	Intrinsic12	Yes	No	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 AND 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 is 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 Since Popper holds both CFD and locality to be true, it is under dispute whether his view is an interpretation (which is what he claimed) or a modification of Quantum Mechanics (which is what many Physicists claim), and, in case of the latter, if it has been empirically refuted or not by Bell test experiments.
• ¹⁴ The transactional interpretation is explicitly non-local.
• ¹⁵ The assumption of intrinsic periodicity is an element of non-locality consistent with relativity as the periodicity varies in a causal way.
• ¹⁶ In the stochastic interpretation is not possible to define velocities for particles, i.e. the paths are not smooth. Moreover, to know the motion of the particles at any moment, you have to know what the Markov process is. However, once we know the exactly initial conditions and the Markov process, the theory is in fact a realistic interpretation of quantum mechanics; trajectories are continuous.
• ¹⁷ The kind of locality violated by the theory is weaker than that assumed in deriving Bell inequalities. In particular, this kind non-locality is compatible with no signaling theorem and so with relativity.
• ¹⁸ The interpretation is compatible with the view of a deterministic world as a whole, but does not exclude indeterminism.
• ¹⁹ There are no hidden variables associated with the state of the quantum entity, but there are hidden variables associated with the measurement-interactions.

My own interpretive approach holds that each particle can be said to contain a string of information, and that this string of information is isomorphic to the particle's normalized relationship to all other particles with which it is interacting, and that these interactions occur in discrete rather than continuous intervals of time. Thus, block-style error correction codes reflect the robustness and endurance of particles in energetic relationships which do not exceed a critical threshold. (Robust baryonic particles such as protons react to powerful forces with energetic responses, rather than being torn asunder. The energy of particle colliders must exceed this threshold value to perform their functions.) The total information of a Feynman diagram is proportional to the total information of the particle, and "local" relationships would tend to predominate in both number of interactions and representation in the information.

First, current theory holds that the wave-function is not real, but reflects a Bayesian uncertainty as to the position of the particle. This Bayesian uncertainty would increase in "free" particles, and decrease in larger particles, or particles locally bound in a larger framework (say, an atom or molecule). Thus, it is easier to be certain as to the location of a molecule as compared to a single atom, and similarly with a comparison of an atom to a subatomic particle, in agreement with experimental evidence. P;D
So let's make that the first item.
Second, real physical phenomena can range from (local and seemingly deterministic) to (non-local and seemingly non-deterministic)

Tabular comparison

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?	Universal wavefunction exists?
Ensemble interpretation	Max Born, 1926	Agnostic	No	Yes	Agnostic	No	No	Agnostic	No	No
Hydrodynamic Interpretation	Erwin Madelung, 1926	Yes	Yes	Yes	Yes	No	No	No	Yes	Yes
Copenhagen interpretation	Niels Bohr, Werner Heisenberg, 1927	No	No1	Yes	No	Yes2	Causal	Agnostic	No	No
de Broglie–Bohm theory	Louis de Broglie, 1927, David Bohm, 1952	Yes	Yes3	Yes4	Yes	No	No	No17	Yes	Yes
von Neumann interpretation	John von Neumann, 1932, John Archibald Wheeler, Eugene Wigner	No	Yes	Yes	No	Yes	Causal	No	No	Yes
Quantum logic	Garrett Birkhoff, 1936	Agnostic	Agnostic	Yes5	No	No	Interpretational6	Agnostic	No	No
Time-symmetric theories	Olivier Costa de Beauregard, 1947, Satosi Watanabe, 1955	Yes	Yes	Yes	Yes	No	No	Yes	No	Yes
Many-worlds interpretation	Hugh Everett, 1957	Yes	Yes	No	No	No	No	Yes	No	Yes
Popper's interpretation	Karl Popper, 1957	No	Yes	Yes	Yes	No	No	(Yes)13	Yes	No
Stochastic mechanics	Edward Nelson, 1966	No	No	Yes	Yes16	No	No	No	Only for position 16	No
Many-minds interpretation	H. Dieter Zeh, 1970	Yes	Yes	No	No	No	Interpretational7	Yes	No	Yes
Consistent histories	Robert B. Griffiths, 1984	Agnostic8	Agnostic8	No	No	No	Interpretational6	Yes	No	No
Objective collapse theories	Ghirardi–Rimini–Weber, 1986, Penrose interpretation, 1989	No	Yes	Yes	No	Yes	No	No	No	No
Transactional interpretation	John G. Cramer, 1986	No	Yes	Yes	No	Yes9	No	No14	Yes	No
Relational interpretation	Carlo Rovelli, 1994	Agnostic	No	Agnostic10	No	Yes11	Intrinsic12	Yes	No	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 AND 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 is 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 Since Popper holds both CFD and locality to be true, it is under dispute whether his view is an interpretation (which is what he claimed) or a modification of Quantum Mechanics (which is what many Physicists claim), and, in case of the latter, if it has been empirically refuted or not by Bell test experiments.
• ¹⁴ The transactional interpretation is explicitly non-local.
• ¹⁵ The assumption of intrinsic periodicity is an element of non-locality consistent with relativity as the periodicity varies in a causal way.
• ¹⁶ In the stochastic interpretation is not possible to define velocities for particles, i.e. the paths are not smooth. Moreover, to know the motion of the particles at any moment, you have to know what the Markov process is. However, once we know the exactly initial conditions and the Markov process, the theory is in fact a realistic interpretation of quantum mechanics; trajectories are continuous.
• ¹⁷ The kind of locality violated by the theory is weaker than that assumed in deriving Bell inequalities. In particular, this kind non-locality is compatible with no signaling theorem and so with relativity.
• ¹⁸ The interpretation is compatible with the view of a deterministic world as a whole, but does not exclude indeterminism.
• ¹⁹ There are no hidden variables associated with the state of the quantum entity, but there are hidden variables associated with the measurement-interactions.