"The wavefunction never collapses"

[javisot]

Regardless of one's objections (e.g. "the measurement problem") to generic Copenhagen-type QM:

The most obvious problem with MWI is that it is falsified by observation. Much like the assertions that the Earth is flat, or angels exist, or so forth. If there are other branches, where are they? I don't see any, no one ever has.

What is the point of saying that MWI is falsified while Copenhagen is not?

These interpretations correspond in the sense that they can explain the same experimental results. In this sense, MWI is like an analytical extension of Copenhagen (I'm speaking in an analogous sense).

 

[PeterDonis]

This is a brutal underestimate

Not necessarily. You are assuming that every single Planck scale spacetime "cell" is decohered from every other. But that's not the case. The MWI does not say that every single quantum degree of freedom is branching at every Planck time. It only says branching occurs when an interaction takes place that results in decoherence, and the only branches are the decohered ones. So, for example, in a Schrodinger's Cat experiment, there would be only two branches, "cat alive" and "cat dead", since those are the two decohered outcomes. There would not be a different branch for every single microscale interaction between the cat's atoms, since those don't decohere separate branches; they just cause the cat to behave classically in the two branches caused by the experiment, "alive" and "dead".

 

[PeterDonis]

What is the point of saying that MWI is falsified while Copenhagen is not?

These interpretations correspond in the sense that they can explain the same experimental results. In this sense, MWI is like an analytical extension of Copenhagen (I'm speaking in an analogous sense).

Please do not pursue this subthread further. What I said in post #27 is all that can be said about it in this forum.