I have a rough time with this distinction. Something not real can still be used to describe a real thing. It just isn't the actual thing. I think more on the lines of what is more fundamental. So I exist, but I'm made of more fundamental matter. Matter exists, but the mathematics underneath seem more fundamental. Below that is what, law of form? None of this stuff 'is real' under RQM, but one part really does relate to others.The issue here is how to interpret the wave-function. If you interpret it as 'real' (or 'representational'), then you are right, there is no selection and the 'other branches' are still 'real' after the measurement.
If, instead, the wave-function is not treated as real/representational (as I think Rovelli does), it does not give a description of reality. — boundless
That doesn't follow from either interpretation of the wave function. It seems to require an additional postulate. A unreal wave function can still describe a multi-state system, and in fact must in order to describe superposition.There is a single outcome given by a probabilistic law.
Reign... Brain fart. :yikes:Everett was forced to reign in his views in order to gain acceptance. — noAxioms
He was shunned by the physics community after his PHD and went into the defense industry instead, but was asked to present his work 5 years after the paper was published. Somewhere around that time DeWitt coined the MWI term from Everett's original "relative state formulation" which sounds an awful lot like RQM.I see. [Everett's] proposal was certainly revolutionary (regardless whether one agrees with him or not).
That works given a postulate of such selection going on. My statement was an opinion, not an assertion.I say it isn't selected at all.
— noAxioms
If one sees the wave-function as real then there is no selection, I agree. Otherwise, there is a 'selection'.
RQM indeed does not claim anything about what path is taken. Any statement about the path taken (such as it taking one or the other) would be a counterfactual one, and RQM is not a counterfactual interpretation. — noAxioms
Right, that's the point, there are epistemic issues with "observations" no matter how you define the term. Sometimes the "observer" might be focused so as to miss many possibly relevant factors. In a human observer, this is one's attention. The person might observe with eyes and not ears, or vise versa, and miss some relevant information. In the case of an observing machine, its capabilities are limited by the intent of the design. — Metaphysician Undercover
Just a curiosity: has anyone ever suggested an interpretation where the 'universal wavefunction' is real (like in MWI) and a single branch is 'selected' by a probabilistic rule (as in Consistent Histories as I understand it)?
This would be similar to the 'unreal' interpretation of MWI referenced in the Wikipedia article about MWI where only one branch is 'real' and the others are not. The only difference is that here there is an explicit axiom of a probabilistic selection. — boundless
On the other hand, it is shown that dynamical collapse models, of the type originally proposed by Ghirardi-Rimini-Weber, can be re-interpreted as set selection criteria within a quantum histories framework, in which context they appear as candidate solutions to the set selection problem. — Quantum Histories - Adrian Kent
Agreed. A human observer and an artifact will interact differently with their environment based on their physical characteristics. And no observer will pick up all the information available during an interaction. However since whether or not there is a hole in the dish is a physical characteristic then a subsequent observation could detect it (either because the human observer directs their attention to it or because the machine is modified to detect it). — Andrew M
The quarry - atomic particles in this case - were found not to have an independent reality, and they were supposed to be the fundamental building blocks of nature. — Wayfarer
Just because something has an indeterminate state from an epistomological point, up to when it's observed, does not mean it does not exist "independently". ( — Benkei
What do you mean "from an epistomological point up to when it's observed"? — frank
Are you saying the particles have location and momentum and so forth prior to observation, it's just that the information is unavailable to us? — frank
If so, does that quantum theory have a name? What is it? — frank
I'm saying that wave function collapse is a matter of knowledge. — Benkei
Is a particle really there when there's no one to observe it? Yes, otherwise experimental physicists would be out of a job or wouldn't bother to share the results with us. — Benkei
.Heisenberg wrote in his well-known 1958 book Physics and Philosophy. “It [quantum physics] introduced something standing in the middle between the idea of an event and the actual event, a strange kind of physical reality just in the middle between possibility and reality.”
In their paper, titled “Taking Heisenberg’s Potentia Seriously,” Ruth Kastner and colleagues elaborate on this idea, drawing a parallel to the philosophy of René Descartes. Descartes, in the 17th century, proposed a strict division between material and mental “substance.” Material stuff (res extensa, or extended things) existed entirely independently of mental reality (res cogitans, things that think) except in the brain’s pineal gland. There res cogitans could influence the body. Modern science has, of course, rejected res cogitans: The material world is all that reality requires. Mental activity is the outcome of material processes, such as electrical impulses and biochemical interactions.
Kastner and colleagues also reject Descartes’ res cogitans. But they think reality should not be restricted to res extensa; rather it should be complemented by “res potentia” — in particular, quantum res potentia, not just any old list of possibilities. Quantum potentia can be quantitatively defined; a quantum measurement will, with certainty, always produce one of the possibilities it describes. In the large-scale world, all sorts of possibilities can be imagined (Browns win Super Bowl, Indians win 22 straight games) which may or may not ever come to pass.
If quantum potentia are in some sense real, Kastner and colleagues say, then the mysterious weirdness of quantum mechanics becomes instantly explicable. You just have to realize that changes in actual things reset the list of potential things. 1
The ones that do usually say that it's not appropriate to talk about location prior to the collapse. Waves don't have specific locations the way particles do. — frank
You're not seeing the problem, again. You're simply asserting that it isn't real. — Wayfarer
They do not really exist, but they're not non-existent. — Wayfarer
I asked a question previously so that seems an odd start is your reply. — Benkei
They do not really exist, but they're not non-existent.
— Wayfarer
This just violates the law of non-contradiction. — Benkei
This difficulty relates to the question whether the smallest units are ordinary physical objects, whether they exist in the same way as stones or flowers. Here, the development of quantum theory some forty years ago has created a complete change in the situation. The mathematically formulated laws of quantum theory show clearly that our ordinary intuitive concepts cannot be unambiguously applied to the smallest particles. All the words or concepts we use to describe ordinary physical objects, such as position, velocity, color, size, and so on, become indefinite and problematic if we try to use then of elementary particles. I cannot enter here into the details of this problem, which has been discussed so frequently in recent years. But it is important to realize that, while the behavior of the smallest particles cannot be unambiguously described in ordinary language, the language of mathematics is still adequate for a clear-cut account of what is going on.
The particle is somewhere within the range of possibilities provided by the probability field. — Benkei
Why measure for position to begin with if the theory does not predict it will be there? They all, even the Copenhagen interpretation, assume when measuring position it will return a result. — Benkei
Heisenberg agreed with me by the way, which is why he uses the term reduction and not collapse. — Benkei
We may be having a translation problem, but it sounds like you're saying that superposition can be understood as a classical physical state, the particulars of which are only known to us by probability. — frank
Not what I meant. The probability describes the possible outcomes of measurement not that at any given moment before measurement it is accurate to say it has a singular position that we just don't know and will discover through measurement. The measurement just brings out a specific property of the object at the expense of all other possible properties "disappearing". — Benkei
But they all do. The particle is somewhere within the range of possibilities provided by the probability field. It is true that by measuring position the thing measured behaves as a particle and not a wave for that measurement but this is a result of it really being neither a wave nor a particle and a limit of language. — Benkei
Which object would that be? — Wayfarer
You're just saying it creates the type of thing we usually think of as a physical object in the same way an artist creates a statue out of clay. — frank
It all hinges on the fact that, for scientific realism, ‘real’ means ‘mind-independent’. That is what has been called into question, and it’s clear from this thread that it’s a very controversial issue. — Wayfarer
What is necessary is to either release the confines of special relativity, allowing light to have physical properties, and describe those properties, or devise a way of observing non-physical properties. — Metaphysician Undercover
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