On Sun, Nov 17, 2024 at 6:06 PM Bruce Kellett <[email protected]> wrote
> *> One of the frequently stated arguments for many worlds is that it > avoids the problem of the wave function collapse. The collapse of the wave > function is only a problem if the wave function is a physical object,* > *Even if you assume, as Copenhagen does, that the quantum wave function is just a prediction device and not a "real physical object" you still have a grave problem; at exactly what point are you supposed to stop trusting what that prediction device is telling you? Copenhagen would answer that you should stop trusting it at the exact point you make a measurement. Physics is the most precise of all the sciences so it would be reasonable to then ask for the exact meaning of this word "measurement", but when you do Niels Bohr and his friends will respond with bafflegab, which I can only interpret as "shut up and calculate". * *By the way, the integers are not physical objects and neither is the concept of "fast", does that mean that both are unreal? If so, how would things be different if both of those things WERE real? I believe that if the wave function didn't lead to conclusions that make some people, perhaps most people, uncomfortable, like there being many other versions of themselves in a multiverse, nobody would be insisting that the wave function is not real. Physicists whose primary focus is physics at its most fundamental level sure seem to behave as if they thought it's real because they spend about 95% of their time studying quantum field theory. * > *> because then you run into problems with instantaneous action at a > distance or FTL physical action.* > *That's no problem in Many Worlds because you can say the split happens instantaneously or you can say the split propagates at the speed of light, it makes no difference because they both produce identical observable results. * * > If the wave function is purely epistemic, namely, nothing more than a > summary of our knowledge about the physical system, there is no problem > with collapse, because the result of an experiment merely updates our > knowledge, and the wave function is updated to reflect this change in > knowledge. * > *That's the Bayesian interpretation and if you use that you will always get the correct answer in your experiments. The exact same thing is true with Shut Up And Calculate. I**f you don't care what's going on and you're only interested in predicting if the needle on your voltmeter will point to 3 or to 4 then I have absolutely no problem with you using either, in fact I think the two ideas are identical, they just have different names. * *> This is exactly what happens in classical probability.* *Not quite. Nobody needed an interpretation of classical physics, nobody needed a definition of "measurement" or "observer" because regardless of the old cliché about a watched pot never boiling, the time it takes to boil a pot of water really doesn't change depending on if you are watching it or not, but in the weird quantum world you really CAN delay the decay of a radioactive atom if you watch it closely enough, and Many Worlds has no problem explaining how this "Quantum Zeno Effect" works. * *Suppose an atom has a half-life of one second and I'm watching it, the universe splits and so do I after one second. In one universe the atom decays and I observed that the atom has decayed, in the other universe the atom has not decayed and I observed that it has not decayed. * *In the universe where the atom didn't decay after another second the universe splits again, and again in one universe it decays but in the other it has not, it survived for 2 full seconds. So there will be a version of me that observes this atom, which has a one second half-life, surviving for 3 seconds, and 4 seconds, and 5 years, and 6 centuries, and you name it. By utilizing a series of increasingly complex and difficult procedures it is possible for the lab (and you) to be in the universe that contains labs and versions of you that see the atom surviving for an arbitrarily long length of time. But the longer the time past its half-life the more splits are involved, and the more difficult the experiment becomes. **Soon it becomes ridiculously impractical to go further, but it's not impossible. * *Quantum Zeno effect* <https://en.wikipedia.org/wiki/Quantum_Zeno_effect> > *> If the wave function is purely epistemic, there is no problem with > collapse, and the additional worlds that MWI introduces play no useful role > and can readily be discarded.* *The useful role that Many Worlds provides is that it doesn't need to explain what a "measurement" or an "observer" is, nor does it need to explain exactly, or even approximately, where the Heisenberg cut is. And it doesn't need to explain what consciousness is because it has nothing to do with it. * *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* zeq -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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