If, as Richard Feyman insisted, nobody understands quantum mechanics

[Anonym]

Where is it written that QM must explain the Measurement Problem?

This is the content of A.Einstein erroneous requirement to the completeness of the Quantum Theory (5-th Solvay Congress). It is Classical Physics must explain the Measurement Problem. It is exactly as in case of Maxwell ED vs Newtonian Mechanics. The less general theory must be reformulated to fit the more general theory and not vice versa. The measurement apparatus obey laws of classical physics. The proper generalization of classical physics (wave mechanics) is required to include the existent formulation and to provide the natural explanation of the collapse of wave function.

Regards, Dany.

P.S. Please give me reference to mentioned paper by R.Peierls.

 

[JesseM]

But I know several things: the brain, on an atomic scale is huge, and very complex. The brain is a classical system -- networks of non-linear electrical devices (neurons). The generation of neural pulses and neural transmission are well understood, described as they are by the Hodgkin-Huxley Eq. There's really no more practically important quantum superposition in the brain than there is in a door bell.

I agree, but what's the theoretical explanation for this? The goal of reductionist physics is to find the most basic laws of the universe, and then understand higher-level laws as emerging from the more basic ones...a reductionist would say that all the laws of chemistry should in principle be derivable from quantum physics (quantum electrodynamics might be sufficient), even though in practice it would be very difficult and only some fairly simple situations like hydrogen atoms have been "reduced" in this way. But there doesn't seem to be any fundamental problem with the idea of such a derivation, whereas the whole issue of collapse and the need for external classical measuring-devices seems to pose a fundamental problem for deriving the classical world from quantum laws. Even if you reject reductionism and imagine that the universe operates according to a sort of patchwork of different laws in different situations, surely nature must have some well-defined rules for the precise conditions where one set of laws is overridden by another set, we don't expect nature to rely on the sort of fuzzy verbal distinctions that we do, that would seem to be a kind of anthropomorphism.

Note that the human mind can effectively be in what might be called a superposition of ideas. That is, "Will I make the next light?" and "What's the probability that an electron can traverse a a slab of crystal, many angstroms thick, without any collisions. That is, I can imagine both making the light and not making the light. When I get there, and say we are talking green, then our "neural pattern " collapses to " made it"-- and that's generically true for any probability situation. In other words, collapse is connected with a change of knowledge.

But in the classical world there is no "interference" between possibilities, you are free to imagine that each object was definitely in one state or another before you observed it. This is like a "mixed state" in QM, which is quite different from a "pure state".

Where is it written that QM must explain the Measurement Problem?

Well, if you want a coherent picture of the universe as a whole, something needs to explain it. I had thought that when you said "my take is that wave function collapse is purely the result of neural learning", you were suggesting some sort of explanation.

 

[Hurkyl]

Perhaps we are deceived in thinking that our mathematical models describe actual reality, when they are really a description of our understanding (perception) of it. Our equations are inventions of our minds just as much as our observations. So collapse of the wave function may be just a feature of the math, not reality itself.

If we had a theory that perfectly described everything we could possibly perceive, then what more could we possibly want? Things that have no perceptible effects are scientifically irrelevant.

 

[Anonym]

Well, if you want a coherent picture of the universe as a whole, something needs to explain it. I had thought that when you said "my take is that wave function collapse is purely the result of neural learning", you were suggesting some sort of explanation.

Bravo! Reilly, you see now where you arrived “after spending time moving lead bricks around for shielding for electron scattering experiments, and working extensively with data from such experiments”. Congratulations!

In addition, go into the street and find “the living and dead cat (pardon the expression) mixed or smeared out in equal parts.”

Regards, Dany.