MWI doesn’t strictly say that the worlds don’t interact. It just says that they are mostly approximately independent if they have decohered (itself a continuous process).
Experiments in controlled conditions show that small sub-branches can, in fact, interfere with each other like waves, hence the double-slit experiment with electrons. But the size of the object merely contributes to the difficulty of the experiment, it seems. So far, large molecules have been used, but in the future it is planned to use viruses and bacteria. See Toward Quantum Superposition of Living Organisms. Also note that a quantum computer is essentially using computation across the multiverse (though no-one has built a particularly large one of those).
Is there any reason to use viruses and bacteria as opposed to, say, bacterium-sized salt crystals? Is it to refute people who say: “But if it’s alive then perhaps it has magical quantum properties. Because life is magical.”
Human consciousness specifically, not just life. Would different interpretations give different predictions for an experiment with a human interfering with himself in other branches?
Are you asking about what this would look like to observers on the side, or about the subjective experience of the person undergoing interference?
Regarding the first question, I don’t think it would be different in principle from any other hypothetical experiment with macroscopic quantum interference; how much different interpretations manage to account for those is a complex question, but I don’t think proponents of either of them would accept the mere fact of experimentally observed macroscopic interference as falsifying their favored interpretation. (Though arguably, collapse-based interpretations run into ever greater difficulties as the largest scales of detected quantum phenomena increase.)
As for the second one, I think answering that question would require more knowledge about the exact nature of human consciousness than we presently have. Scott Aaronson presents some interesting discussion along these lines in one of his lectures: http://www.scottaaronson.com/democritus/lec11.html
Nope. The copenhagen interpretation says that the wavefunction collapses when it interacts with anything.
But the thing it interacts with is still part of a larger wavefunction until that collapses etc.
Schroedingers Cat is about this fact, the fact that a cat (an observer) can be superposed.
I have yet to work out what the difference is between the Copenhagen Interpretation and the Many Worlds Interpretation. The physical reality they describe is identical.
Thanks for the link. I’m still not clear on exactly what it would mean to be able to interfere with myself in other branches in a wave-like way. Also, I thought a non-reversible process forced decoherence: is this not correct, or is there a way to force living organisms to be reversible?
MWI doesn’t strictly say that the worlds don’t interact. It just says that they are mostly approximately independent if they have decohered (itself a continuous process).
Experiments in controlled conditions show that small sub-branches can, in fact, interfere with each other like waves, hence the double-slit experiment with electrons. But the size of the object merely contributes to the difficulty of the experiment, it seems. So far, large molecules have been used, but in the future it is planned to use viruses and bacteria. See Toward Quantum Superposition of Living Organisms. Also note that a quantum computer is essentially using computation across the multiverse (though no-one has built a particularly large one of those).
Is there any reason to use viruses and bacteria as opposed to, say, bacterium-sized salt crystals? Is it to refute people who say: “But if it’s alive then perhaps it has magical quantum properties. Because life is magical.”
Yes. It is way cooler. Kind of like levitating frogs with superconducting magnets.
Well, isn’t the copenhagen interpretation the statement that life has magic effects on physics, by causing the wavefunction to collapse?
Human consciousness specifically, not just life. Would different interpretations give different predictions for an experiment with a human interfering with himself in other branches?
Are you asking about what this would look like to observers on the side, or about the subjective experience of the person undergoing interference?
Regarding the first question, I don’t think it would be different in principle from any other hypothetical experiment with macroscopic quantum interference; how much different interpretations manage to account for those is a complex question, but I don’t think proponents of either of them would accept the mere fact of experimentally observed macroscopic interference as falsifying their favored interpretation. (Though arguably, collapse-based interpretations run into ever greater difficulties as the largest scales of detected quantum phenomena increase.)
As for the second one, I think answering that question would require more knowledge about the exact nature of human consciousness than we presently have. Scott Aaronson presents some interesting discussion along these lines in one of his lectures:
http://www.scottaaronson.com/democritus/lec11.html
Nope. The copenhagen interpretation says that the wavefunction collapses when it interacts with anything.
But the thing it interacts with is still part of a larger wavefunction until that collapses etc.
Schroedingers Cat is about this fact, the fact that a cat (an observer) can be superposed.
I have yet to work out what the difference is between the Copenhagen Interpretation and the Many Worlds Interpretation. The physical reality they describe is identical.
Thanks for the link. I’m still not clear on exactly what it would mean to be able to interfere with myself in other branches in a wave-like way. Also, I thought a non-reversible process forced decoherence: is this not correct, or is there a way to force living organisms to be reversible?