a number of people seem to think that MWI means that any world you can verbally describe exists somewhere, rather than just worlds that have split off from quantum events. No, there is not necessarily a world out there in which the Nazis won WWII.
But all but the most fundamental (e.g. particle masses) asymmetry/”randomness” in the world comes from quantum events, no? Which would imply that every physically possible world (up to the size of the universe, if it’s finite) exists in the wavefunction under a pretty broad definition of “physically possible”, including Nazi victories and simulations of all physically impossible but logically possible worlds.
But all but the most fundamental (e.g. particle masses) asymmetry/”randomness” in the world comes from quantum events, no?
Correct. There is branch of the wavefunction where a large sperm whale and a bowl of petunias were spontaneously created 500 miles above the city of Copenhagen exactly 10 minutes ago.
Even if Robin is not right about mangled worlds, I don’t think this is right. Why would there necessarily be a quantum event that produced a sperm whale and a bowl of petunias? (“Oh no, not again.”)
But tunneling, and atoms even, are classical concepts, not QM concepts. I’m confused here, but I suspect that others are as well. My impression is that the best pseudo-classical perspective is that anything can appear anywhere at any time with low probability (!!) but that it’s confusion to think in terms of classical objects doing anything but following classical physics as the classical particles, indeed the classical objects, simply ARE the math of classical physics which is approximated by QM. This is a nit to pick perhaps, but it seems to me that the proper understanding of Boltzman Brains involves this line of attack as well as a Turing Machine refoundation.
I’ve yet to see a clear answer on this. My understanding was that quantum events occur when a particle interacts with another particle in such a way as to yield different outcomes depending on its spin (essentially “measuring” the spin). There are exactly two possibilities and the world only splits into two.
It’s not at all clear that you can arrange the possibilities into a world where a sperm whale spontaneously appears. I would love to see a correction or further explanation.
But all but the most fundamental (e.g. particle masses) asymmetry/”randomness” in the world comes from quantum events, no? Which would imply that every physically possible world (up to the size of the universe, if it’s finite) exists in the wavefunction under a pretty broad definition of “physically possible”, including Nazi victories and simulations of all physically impossible but logically possible worlds.
Correct. There is branch of the wavefunction where a large sperm whale and a bowl of petunias were spontaneously created 500 miles above the city of Copenhagen exactly 10 minutes ago.
Not if Robin’s right about mangled worlds.
Even if Robin is not right about mangled worlds, I don’t think this is right. Why would there necessarily be a quantum event that produced a sperm whale and a bowl of petunias? (“Oh no, not again.”)
Nearby atoms tunneling into the appropriate places.
But tunneling, and atoms even, are classical concepts, not QM concepts. I’m confused here, but I suspect that others are as well. My impression is that the best pseudo-classical perspective is that anything can appear anywhere at any time with low probability (!!) but that it’s confusion to think in terms of classical objects doing anything but following classical physics as the classical particles, indeed the classical objects, simply ARE the math of classical physics which is approximated by QM.
This is a nit to pick perhaps, but it seems to me that the proper understanding of Boltzman Brains involves this line of attack as well as a Turing Machine refoundation.
I’ve yet to see a clear answer on this. My understanding was that quantum events occur when a particle interacts with another particle in such a way as to yield different outcomes depending on its spin (essentially “measuring” the spin). There are exactly two possibilities and the world only splits into two.
It’s not at all clear that you can arrange the possibilities into a world where a sperm whale spontaneously appears. I would love to see a correction or further explanation.
Spin is popular for examples and experiments, but it’s not fundamentally special; all physical properties are subject to QM in the same way.
Have you read the Quantum Physics Sequence?
I don’t think that this is certain at all. Also, our intuitions of what counts as logically possible are terribly terribly unreliable.