All of Bob5's Comments + Replies

Caledonian: There is no difference at the level of predictions, because I'm not calling for any new laws of physics beyond QM. It's a matter of what makes sense as interpretation.

Don Geddis: I don't agree that "multiple worlds are observed, in subatomic phenomena. That's what superposition is." That is your preferred interpretation. I prefer to think that the wavefunction is real, but it is a function over potential configurations, only one of which is real. Superposition reflects the influence of other physically equivalent configurations. I would not call my interpretation a "collapse" interpretation. The wavefunction is always there, in the sense that nature "knows" the probability amplitude ... (read more)

4Rob Lucas
If "the wavefunction is real, but it is a function over potential configurations, only one of which is real." then you have the real configuration interacting with potential configurations.  I don't see how you can say something isn't real (if only one of them is real then the others aren't) is interacting with something that is.  If that "potential" part of the wave function can interact with the other parts of the wave function, then it's clearly real in every sense that the word "real" means anything at all.

So to preserve the illusion of determinism, which is not observed, you concoct the illusion of multiple worlds, which are also not observed. (feel free to imagine the preceding in all caps, to reflect my righteous indignation).

Eliezer: No doubt I am missing a lot. I have the idea of the wavefunction as a real thing, and I am not advocating a collapse interpretation. I am also uncomfortable with any kind of preferred basis. My idea is that the configuration space of the universe is the classical configuration space, but that its evolution is determined by the wavefunction over the quantum mechanical configuration space (in whatever basis you choose). So a point-particle has a real momentum and a real position, which are not simultaneously measureable. For electromagnetism, t... (read more)

0punctumm
Actually, they are the same thing, so if you know one, you know the other... they are definitely NOT conjugate variables (variables that cannot be measured at the same time).

Bob: We may still believe that the universe comprises a single point in configuration space, >>corresponding to a single value of the wavefunction

How is this not immediately ruled out by Bell's Theorem?

Bell's Theorem rules out local realism. I'm going with "non-local".

Does the reality of the wavefunction imply MWI? The wavefunction is a function over every possible configuration of the universe. We may still believe that the universe comprises a single point in configuration space, corresponding to a single value of the wavefunction, along with the value of the wavefunction for every other (counterfactual) point in the configuration space. The reality is the particular configuration space point along with the shape of the wavefunction. This does not imply that the wavefunction is a delta-function in configuration space. Other counterfactual configurations may have similar probability amplitudes depending on their "degree of possibility" compared to the existing configuration.

OK, so now it's pretty clear you're committed to a many-worlds interpretation. When I'm done with your experiment, I don't see two blobs, just one. Because there is a separate Bob-blob corresponding to each outcome.

This has been a fascinating series of posts. You are suggesting a realistic interpretation of QM. Do you take the real universe to be the (single) point in the universal QM configuration space, along with the single complex value of the universal wavefunction? Or, since the wavefunction is a function of all possible configurations, are those other configurations somehow real as well (which would be some sort of multiverse theory)? Quantum mechanics certainly allows wavefunctions comprising superpositions of different configurations. Are these superposition states not fundamental?

0Ramana Kumar
No, the universe is an (evolving) amplitude distribution over configuration space. I'm not what "superposition state" means, but my guess is that the answer to "Are these superposition states not fundamental?" is "Yes they are".