[lmm]

> The collapse (from our point of view, at least) of the wave function is pretty necessary in the math of QM.

The measurement results are mathematically necessary. The Copenhagen interpretation, that this means there is a physical collapse in the wavefunction, is not.

> To me, it seems that other theories are just disputing what the "collapse" fundamentally means.

If you substitute "collapse" for "measurement" this is pretty much true. What else could "different interpretations of a theory" mean?

[scotty79]

I think that QM is actually covering two very distinct things.

One is about what actually happens. This contains Shrodinger equation and similar things.

The other is about what results will we get if we poke the particles with macroscopic objects disturbing them beyond recognition. That's the all math where the word "measurement" is used.

Somehow we think the science of what happens to a frog when you poke it with a knife is a part of zoology. It's important, it might be even more important than zoology, but that's a different domain of science.

[ravi-delia]

That's all well and good in zoology, but since both the experiment and experimenter are quantum systems, QM has to explain any and all interactions between the two. Measurement can't be some extraneous thing to what's happening, since it too is happening. I think decoherence gets some points on that mark, I'd be shocked if anyone really thought collapse wasn't the product of some yet undiscovered (or at least unconsidered) aspect of quantum physics.