About the Copenhagen interpretation

Here is my reply to the article by Luboš Motl, Von Neumann-Wigner interpretation was just "verbally spiced" original Copenhagen.

First an unserious remark: "Heisenberg, Bohr, Dirac, Jordan, Born, as well as Wigner and von Neumann would agree. They may have used different words about other aspects but the differences were unphysical". Is the adjective "unphysical" used as synonymous with something like "unreal", and if yes, why (considering the fact of rejecting physical realism, a circumstance which might have led to regard any qualification of "physicality" as pejorative)? Maybe by looking at physics not as a field of reality but as a field of science - so that the adjective "unscientific" would have been more appropriate.

As mentioned in my classification of interpretations, I regard (define) the Copenhagen "interpretation" not as a genuine interpretation, but rather as a refusal to interpret : that is
and focus on technical aspects instead (predicting and experimenting).
I still technically include it in the list of interpretations because many people adopt it, and because, as an attitude instead of an interpretation, it also has its legitimacy, that is, as an expression of the scientific method.
We can metaphorically qualify the situation in quantum terms themselves, that is: the Copenhagen interpretation would consist in a state of superposition between different particular other interpretations, waiting for a measuring instrument that would be good enough to distinguish them.
Thus one may speculate either that such an instrument will someday be found to validate one interpretation (other than Copenhagen) against all others, or that it will/can never be found, so that this indetermination would stay forever; which would make Copenhagen "true" in this sense of a persisting indetermination.

In particular, one might identify the Copenhagen interpretation as describing the limit case of Spontaneous Collapse theories, assuming this collapse to happen well after decoherence, in a range of observations and approximations where the effects of this spontaneous collapse would be below detection level. In these terms, a Mars rover can be admitted as a legitimate observer, since it is just as macroscopic and able of decoherence as human observers; while both Mind makes collapse and Many-worlds would regard the rover as unable of wavefunction collapse.

Now, I will propose 2 kinds of demarcation criteria between the Mind makes collapse interpretation and the rest of interpretations (including Copenhagen) : the first ones will be "purely philosophical" criteria, and the last ones will address verifiable predictions.

One crucial philosophical distinction, is how it relates to solipsism, i.e. how it interprets the Wigner's friend experiment. And  it is the only issue for which we can conceive the Copenhagen interpretation as able to effectively depart from all the rest of interpretations (though we shall later ignore this distinct option, to focus on its view as "indetermination between other interpretations"):

In fact we have 3 options:
Absolute solipsism Relative solipsism
Copenhagen Many-worlds
Bohm, Spontaneous collapse,
Mind makes collapse
Collapse is defined as purely that of one's own observations The diverse definitions of the collapse relatively to different observers are equally valid in parallel
Measurement result is "absolutely real" no later than when perceived by the first conscious observer (maybe different from oneself)

So, when Luboš writes in the comments of his article that
"the moment when the wave function collapses generally depends on the observer.(...) when the correlation exists - e.g. when we only trust the people who do not lie and who are capable of finding the right result - all the correlations that are needed to reconstruct the "objective reality of the history" retroactively will be perfectly satisfied."
he is actually adopting a Relative Solipsism approach, i.e. the Many-Worlds interpretation (at least in case he would mean to seriously regard his approach as ontologically valid, rather than as a mere calculation technique). Anyway, relative solipsism remains correct as a mere calculation technique regardless of the interpretation, when ignoring ontological questions, but now we shall trying to address ontological questions, so that we are going to put aside the computational motivations for the concepts of relative states as off-topic.

For more comments on the meaning and consequences of Relative Solipsism, see my page on Many-worlds.
Now, as the case of the above example was not discussed in that other page, let us comment it further here.
If taken ontologically, his reply seems to deny any difference between
Such a way of moving the Heisenberg cut to let it separate the past (on the observed side) from the present of the same person (on the observer side), would be plagued with the same trouble as the case of slow spontaneous collapse.
And this Heisenberg cut also comes with an ontological division between a past real conscious perception and one's later conscious memory of it. Namely : can our memory of the past be a reliable witness of the past reality of our perceptions ? But how could a "fact that I am really experiencing something now", finally turn out to be a fact that was not yet real at the present time but will only be made real later ; and moreover, it will be made real later by something else (a physical process of spontaneous collapse), or by someone else (receiving my testimony) and only as their later option of a possible present (then in their past) among other possible alternatives ?
But things get even worse if this future reconstruction of reality, that is expected to retrospectively give full reality to a not-yet-fully-real present conscious observation, is not yet sure to happen.
For example, what if Wigner's friend in a room opens the box to see if the cat is alive or dead, but after he sees it, the whole room is destroyed by an atomic bomb (or falls into a black hole - or maybe he already passed the horizon of a black hole before opening the box) so that he dies anyway and no trace remains of what he could see of the cat : was his observation real or not ?
In his comments, in answer to the hypothesis of living in a computer simulation, Luboš claims being pretty sure of having personally verified a lot of things, including the laws of physics in pretty much details. But he only remembers having verified these things. So, his testimony is only valid insofar as he would have a proof that his memory doesn't fool him. But if his memory only consisted in material configurations of his neurons, then... where is the personally verified physical evidence that these configurations in his brain are faithful ? while it is not even scientifically understood how conscious memory works !
To this my solution, as part of the mind makes collapse interpretation as I see it, and as I further commented, is that memory can be valid direct evidence of past experiences because the fundamental nature of memory is NOT that of material configurations in the brain, but it consists in the immaterial, indestructible reality of this past experience itself ; and this memory is even indestructible by death (there is a life after death) even if it can be obscured (temporarily forgotten). Thus, this interpretation rejects the idea of putting someone's past conscious observation events on the object side of the Heisenberg cut (to be only "observed" like any physical system in the form of available physical memory in the brain), as just plain wrong.

Now let us come to differences in verifiable predictions. There is a fundamental difference of verifiable predictions that distinguishes the Mind makes collapse from all other interpretations (including Copenhagen): that probabilities can be modified by free will.
In another article, he (unless I mistake with someone else ? I could not get back the link, even by google) referred to a classification of views about free will ; and that this classification has put his view in the category "libertarian" but he didn't see the sense of it. Of course it did not make sense in this precise way : the intended idea of libertarian free will is not just to believe (as 2 different claims coming by coincidence) in both indeterminism and just some concept that can be named "free will" regardless of details.
The concept of free will he refers to, is the logically necessary one, expression of time order : an inability to predict one's own future behavior, which I consider to similarly but independently happen in 3 realms : finite mathematics (algorithmic), infinite mathematics, and consciousness.
However, what was meant instead by libertarian free will, consists in making sense of the claim of conscious free will in its physically measurable behavior, as explained by the fundamental indeterminism of physical laws, based on the difference of roles between both realms : letting the immaterial consciousness make use of indeterministic laws of physics as a tool to exert its free will (with non-physical source) onto physical systems - thus choosing the behavior of these physical objects away from any strict (unconscious) obedience of physical probability laws.

Thus we get verifiable (falsifiable) predictions, that can scientifically distinguish the Mind makes collapse from Copenhagen predictions, that may be roughly split into 3 kinds (2 of them being traditional experimental fields of parapsychology):
  1. Psychokinesis : an observer's free will is exerted on the outcome of a quantum randomness device, whose probability law is well-known, so that deviations from these probabilities can be precisely measured. The usual problem is that these deviations are tiny, hard to distinguish from pure chance. Eventually, psychokinesis may be operated by ghosts as well (haunted houses). But it has been experimented with a cat, with positive results.
  2. Analyze the human brain processes and logically deduce what quantum physics actually predicts of its behavior; notice that philosophical zombies physically identical to normal people and obeying physical probabilities would actually behave very differently than normally conscious humans : they may be in a sort of coma, and would anyway fail at the Turing test. The difficulty here is not in having an effect away from physical laws, but in figuring out what would come from an absence of effect for comparison.
  3. Circumvent the direct difficulties of 2 by exploring special states or operations of consciousness (OBE, hypnosis, telepathy...) for which the logical impossibility of explanation by purely physical processes becomes more obvious than for ordinary conscious behaviors.

Now in reply to (about the animals ability to collapse the wave function) "the point of positivism is that none of these "precise" choices of the demarcation line can be measured, so they are *unphysical* questions".
No. The point of positivism is to focus one's study on the issues of what we can measure, and to only call scientific what can be measurable, whatever it might be, no matter whether something specific is already known or expected (by whom ?) to be measurable or not. Thus, the question of the ability of animals to collapse the wave function, becomes a scientific question as soon as we consider their ability to practice free will so as to differ in probable behavior from their physically identical zombie. And as linked above, it has been shown that a cat suffices to collapse a wave function, as it has been observed to influence the result.

And such an ability is well conceivable to occur for animals with intelligence way below any ability to be good experimental physicists making experiments to verify the correctness of quantum probabilities, a confusion between the role of a conscious observer to collapse the wave function (making a measurement consciously real), and the guidelines of logical positivism to do good science, which I see completely displaced here.
The possible presence of passive conscious observers, which only see events following their physical probabilities rather than directly putting bias on them, should not be excluded either ; and nothing says that passive observations would remain unobservable and thus unscientific. Their reality might still be indirectly verified, such as when reporting of out-of-body observations that were passive at the moment but become active to witness these observations from (immaterial) memory once back in the brain.
"the true internal feelings of others can't be measured"
Well this is very hard to measure indeed, maybe as hard as the Higgs boson, but in the mind makes collapse interpretation it is not an absolute impossibility : things like telepathy remain possible. And some NDEs report some transfers of feelings between different individuals, such as during the life review.

Conclusion : no, in the precise way I conceive it, the Mind makes collapse interpretation is not just "verbally spiced" original Copenhagen. It is much more specific in its ontology, and it brings its own different predictions.

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Set Theory and foundations of mathematics
Foundations of physics
Interpretations of quantum physics