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I'm not unaware that formalism alone employs the right concepts to understand what quantum superposition is, and the interference it makes possible. Nevertheless, I'd like to know what images, in the eyes and ears of physicists (not being one myself), to describe as loosely as possible this process that is interference between two eigenstates of a wavefunction. Insofar as this is a dynamic interaction that preserves the conceptual individuality of the superimposed states, would it be legitimate to speak of an "interweaving" or "intertwining" of these states? Let me make it clear that I'm talking here about "partial" interferences, in the sense of those that are neither constructive nor destructive (the constructive ones undoubtedly implying more than an interweaving; a kind of mutual "fusion").

I see several advantages in this;

A) Interweaving suggests that superimposed quantum states are linked in a complex, interconnected way, while retaining their individuality. Indeed, interlacing implies both the unity and the separation of its relata; and indeed, the interfering states are nonetheless distinct from one another (it's one of these, and only one, that I'll be measuring). B)This metaphor emphasizes the fact that superimposed states are not simply randomly mixed, but coherently combined with complex amplitudes. C) Finally, this image of interlacing can quite naturally be associated with notions of correlation and non-separability between quantum states.

What do you think? Is this a relevant image for the quantum interference process?

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For two reasons, interweaving is not a helpful analogy.

Firstly, it implies some degree of mutual twisting around, whereas interference or superposition is no more than an addition.

Secondly, it doesn't convey the idea of proportionality. In a woven structure, you typically have multiple strands of the same thickness. In a superposition of eigenfunctions, each may be represented to a different degree. You might, for example, have a mix which includes 80% of one function, plus 9% of another, plus 5% of another plus 2% of another, and so on, rather than each function contributing the same proportion.

If you want a practical analogy, consider the sound produced by a musical chord. If you strum a chord on a guitar, say, the resulting vibration of the air is the sum of the vibrations caused by the individual strings.

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  • Thanks ! I particularly like the second objection. As for the first, my point was precisely 1) to dissociate superposition and interference and 2) to consider only those interferences that are neither constructive nor destructive. In.the.case.of.the former,.there is addition.(where your analogy works, it seems),and in the case of the latter, there is subtraction. Question: if we're neither in addition nor subtraction, aren't we in an intermediate case, where states are conjoined and disjoined? This ambiguity is perhaps best conveyed by the image of interweaving -- my assomption ! Apr 21 at 0:06
  • marco has a physics PhD @Husserliana !
    – andrós
    Apr 21 at 2:34
  • @Husserliana addition and subtraction are the same operation physically. You are overlaying, if you like, two functions. Where they both are positive, or both are negative, they reinforce each other. Where one is positive and the other negative, they cancel out to some extent. Apr 21 at 6:06
  • Thanks for this clarification! So whether they're in phase or not, we can talk about additionne. With this image of interlacing, I mainly wanted to emphasize that the states add to each other, despite a "gap" between them, but a gap in a metaphorical sense; since they are indeed separated in the definition space (let's say Hilbert's), as vectors distinct from each other. (And the idea of interlacing captures this conjunction/disjunction) Or am I wrong...? Apr 21 at 7:25
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I'm not a physicist, but I've spend more time studying this topic that I would like to admit, and here are my two cents.

First and foremost, there are no perfect analogies to quantum mechanics. There are some better than others, and some of them helps you to take a grasp on understanding the principles, but all are relatively bad in representing reality. This happens because you are trying to understand QM by thinking classically, and this will never work.

Instead, it is best to go for another route. First, just accept that the universe is quantum and accept that classical physics is a emergent phenomena. Accept that the laws of quantum mechanics are the true nature of the universe, and that we experience a narrow slice of the quantum reality (what we call a real and local universe). Also, accept that quantum mechanics is a complete theory (in the sense that the problems it has with gravity and stuff are a problem in relativity, not QM).

If you go down this route, you will be inclined to choose "Many Worlds" (the original version aka Universe Wavefunction), "Consistent Histories" or some other non-collapsing theory as your favorite interpretation. Every interpretation in this flavor will get you multiple (infinite?) timelines, and you can just think about spacetime having 3 dimensions of space and 2 (maybe more?) of time.

This maybe confusing at first, but the more you think about it, the more it makes sense (assuming you believe in multiple histories). This plays really nice with the wave function and the Schrödinger equation, and it is not that hard to visualize it. This also plays nice with Quantum Darwinism, which is related to your question. This is an excellent video on the topic. You will be close to make intuitive sense of QM. You will naturally come to conclusion that a non deterministic classical world is a deterministic world with more time dimensions.

Also remember that every model is wrong, but some of them are useful.

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