I have heard of versions of many-worlds that are supposed to be testable, and you’re probably referring to one of them. The one that I’m most familiar with (“classic many-worlds”?) is much more of a pure interpretation, though: in that version, there is no collapse and the apparent collapse is a matter of perspective. A component of the wavefunction that I perceive as me sees the electron in the spin-down state, but in the big superposition, there’s another component like me but seeing the spin-up state. I can’t communicate with the other me (or “mes,” plural) because we’re just components of a big vector—we don’t interact.
On the other hand, classic decoherence posits that the wavefunction really does collapse, just not to 100% pure states. Although there’s technically a superposition of electrons and a superposition of mes, it’s heavily dominated by one component. Thus, the two interpretations, classic many-worlds and classic decoherence, are different interpretations.
If the state of theory and/or experiment developed further and these asymptotic projections were shown to exist in generality, that would bolster decoherence but not eliminate many-worlds: you could still imagine a 0.0001% me being coupled with the spin-up electron. It would, however, undermine the motivation. If, instead, these asymptotic projections were shown to not exist, then that would undermine decoherence to the point of refutation (i.e. only die-hards would keep looking for variants of the theory that aren’t ruled out). So classic decoherence is more falsifiable than classic many-worlds. That’s what I mean by saying that many-worlds is more purely philosophical.
But I was careful to say “classic” everywhere. With this being such an active area of research, I’m sure there are versions of these theories that don’t fit the description above. (They’re all “more than one theory.”) As I said, I’ve heard of variants of many-worlds that are less purely philosophical, and that must be what you’re referring to, @TAG.
I have heard of versions of many-worlds that are supposed to be testable
The’re are versions that are falsified, for all practical purposes, because they fail to.predict broadly classical observations—sharp valued real numbers, without pesky complex numbers or superpositions. I mean mainly the original Everett theory of 1957. There have been various attempts to patch the problems—preferred basis, Decoherence , anthropics, etc, -- so there are various non falsified theories.
The one that I’m most familiar with (“classic many-worlds”?) is much more of a pure interpretation, though: in that version, there is no collapse and the apparent collapse is a matter of perspective. A component of the wavefunction that I perceive as me sees the electron in the spin-down state, but in the big superposition, there’s another component like me but seeing the spin-up state. I can’t communicate with the other me (or “mes,” plural) because we’re just components of a big vector—we don’t interact.
Merely saying that everything is a component of a big vector doesn’t show that observers dont go into superposition with themselves, because the same description applies to anything which is in superposition..it’s a very broad claim.
What you call classic MWI is what I the have-your-cake-and-eat-it … assuming nothing except that collapse doesn’t occur, you conclude that observers make classical observations for not particular reason...you doing even nominate Decoherence or preferred basis as the mechanism that gets rid of the unwanted stuff.
On the other hand, classic decoherence posits that the wavefunction really does collapse, just not to 100% pure states. Although there’s technically a superposition of electrons and a superposition of mes, it’s heavily dominated by one component. Thus, the two interpretations, classic many-worlds and classic decoherence, are different interpretations.
OK. I would call that single world decoherence. Many worlders appeal to Decoherence as well.
So classic decoherence is more falsifiable than classic many-worlds.
If classic MW means Everetts RSI, it’s already false.
I have heard of versions of many-worlds that are supposed to be testable, and you’re probably referring to one of them. The one that I’m most familiar with (“classic many-worlds”?) is much more of a pure interpretation, though: in that version, there is no collapse and the apparent collapse is a matter of perspective. A component of the wavefunction that I perceive as me sees the electron in the spin-down state, but in the big superposition, there’s another component like me but seeing the spin-up state. I can’t communicate with the other me (or “mes,” plural) because we’re just components of a big vector—we don’t interact.
On the other hand, classic decoherence posits that the wavefunction really does collapse, just not to 100% pure states. Although there’s technically a superposition of electrons and a superposition of mes, it’s heavily dominated by one component. Thus, the two interpretations, classic many-worlds and classic decoherence, are different interpretations.
If the state of theory and/or experiment developed further and these asymptotic projections were shown to exist in generality, that would bolster decoherence but not eliminate many-worlds: you could still imagine a 0.0001% me being coupled with the spin-up electron. It would, however, undermine the motivation. If, instead, these asymptotic projections were shown to not exist, then that would undermine decoherence to the point of refutation (i.e. only die-hards would keep looking for variants of the theory that aren’t ruled out). So classic decoherence is more falsifiable than classic many-worlds. That’s what I mean by saying that many-worlds is more purely philosophical.
But I was careful to say “classic” everywhere. With this being such an active area of research, I’m sure there are versions of these theories that don’t fit the description above. (They’re all “more than one theory.”) As I said, I’ve heard of variants of many-worlds that are less purely philosophical, and that must be what you’re referring to, @TAG.
The’re are versions that are falsified, for all practical purposes, because they fail to.predict broadly classical observations—sharp valued real numbers, without pesky complex numbers or superpositions. I mean mainly the original Everett theory of 1957. There have been various attempts to patch the problems—preferred basis, Decoherence , anthropics, etc, -- so there are various non falsified theories.
Merely saying that everything is a component of a big vector doesn’t show that observers dont go into superposition with themselves, because the same description applies to anything which is in superposition..it’s a very broad claim.
What you call classic MWI is what I the have-your-cake-and-eat-it … assuming nothing except that collapse doesn’t occur, you conclude that observers make classical observations for not particular reason...you doing even nominate Decoherence or preferred basis as the mechanism that gets rid of the unwanted stuff.
OK. I would call that single world decoherence. Many worlders appeal to Decoherence as well.
If classic MW means Everetts RSI, it’s already false.