User:TheLastWordSword/Sandbox

This is my Sandbox. There are many sandboxes like it, but this one is mine.

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.

Locality and Temporal Causation are both the rules, with perhaps some notable exceptions. Counter-factual definiteness is only applicable to focused human efforts to measure microscopic systems, and would seem to me to be unreliable under high-locality conditions. Under low-locality conditions, however, CFD may not only be reliable, but rather handy for some applications. P;D

Interpretation	Author(s)	Deterministic?	Wavefunction real?	Unique history?	Hidden variables?	Collapsing wavefunctions?	Observer role?	Local?	Counterfactual definiteness?
Quantum logic	Garrett Birkhoff, 1936	Agnostic	Agnostic	Yes⁵	No	No	Interpretational⁶
Consistent histories	Robert B. Griffiths, 1984	Agnostic⁸	Agnostic⁸	No	No	No	Interpretational⁶	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 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 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.

EPR Paradox[edit]

Albert Einstein felt that there was something fundamentally incorrect with quantum mechanics since it predicted violations of the principle of locality. Seeking to undermine quantum mechanics, in a famous paper he and his co-authors articulated the Einstein-Podolsky-Rosen Paradox. Thirty years later John Stewart Bell responded with a paper which posited (paraphrased) that no physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics (known as Bell's theorem).

Philosophical view

Einstein assumed that the principle of locality was necessary, and that there could be no violations of it. He said[1]: “ The following idea characterizes the relative independence of objects far apart in space, A and B: external influence on A has no direct influence on B; this is known as the Principle of Local Action, which is used consistently only in field theory. If this axiom were to be completely abolished, the idea of the existence of quasi-enclosed systems, and thereby the postulation of laws which can be checked empirically in the accepted sense, would become impossible. ”

COMMENTS: The reproducibility of an experiment would become statistical rather than absolute; and as anyone who has had an experiment ruined by some nincompoop bumping into their elbow can attest, that is already the case, even in "empirical" research and experimentation.

Realism

Realism in the sense used by physicists does not equate to realism in metaphysics.[2] The latter is the claim that the world is in some sense mind-independent: that even if the results of a possible measurement do not pre-exist the act of measurement, that does not require that they are the creation of the observer (contrary to the "consciousness causes collapse" interpretation of quantum mechanics). Furthermore, a mind-independent property does not have to be the value of some physical variable such as position or momentum. A property can be dispositional (or potential), i.e. it can be a tendency: in the way that glass objects tend to break, or are disposed to break, even if they do not actually break. Likewise, the mind-independent properties of quantum systems could consist of a tendency to respond to particular measurements with particular values with ascertainable probability.[3] Such an ontology would be metaphysically realistic, without being realistic in the physicist's sense of "local realism" (which would require that a single value be produced with certainty).

COMMENTS: This type of distinction seems to be the heart of the argument; whether the scientific process itself can have its own philosophy separate from the body of philosophy already had through an independent process. I'd like to clear this up here: my answer is "No, it cannot." and I have the inside track on this subject; whether you believe so or not, it is a fact independent of your beliefs. And you don't have to like it, either; you can lump it.

Local realism is a significant feature of classical mechanics, of general relativity, and of electrodynamics; but quantum mechanics largely rejects this principle due to the theory of distant quantum entanglements, an interpretation rejected by Einstein in the EPR paradox but subsequently apparently quantified by Bell's inequalities.[4] Any theory, such as quantum mechanics, that violates Bell's inequalities must abandon either local realism or counterfactual definiteness; but some physicists dispute that experiments have demonstrated Bell's violations, on the grounds that the sub-class of inhomogeneous Bell inequalities has not been tested or due to experimental limitations in the tests. Different interpretations of quantum mechanics violate different parts of local realism and/or counterfactual definiteness.

COMMENTS: In electrostatic friction, the momentum and the position of the particles (electrons) are "measured" in tandem, and neither value is measured to any high level of precision (see Wojciech H. Zurek and external links). If Bell's Theorem is anything like Heisenberg's Uncertainty principle, then we can have a partial value for both variables, locality and counter-factual definiteness. Mistaking the abstract and extreme cases of such philosophical concepts for their only conditions is a mark of those who aren't familiar with the territory and methodology of Philosophy. Such an approach is helpful for testing the limits of a philosophical idea, but doesn't help to establish its "normative" conditions and uses.