Unlike the Copenhagen interpretation, it does not privilege measurement over other types of interactions between systems.
Hmm, you could say it instead privileges the subjective experience over other types of interaction. There’s no reason in principle why you couldn’t experience every “world” at the same time, in the same way a measurement could in principle return all possible results at the same time.
But you don’t. Somehow your experience of reality is above unitary time evolution, even though “you” aren’t.
I agree completely that that the Copenhagen interpretation makes an excellent phenomenological model in simple (albeit, very common!) settings. However, the problem is that it breaks down when you consider experiments such as the “quantum eraser” (mentioned in other comments here), which causes people to tie themselves into intellectual knots because they are thinking too hard about exactly what is going on with measurement; once one deprivileges measurement so that it becomes just another kind of interaction, the seeming paradoxes disappear.
Copenhagen interpretation doesn’t break down for quantum erasure. Upon measurement you collapse the total quantum state into a result where the two measurements are consistent, that’s simply what entanglement means.
The timing of experiments, and the choice of what to measure, are elements ultimately irrelevant to the above statement, as the quantum erasure experiment demonstrates.
To clarify my imprecise language, what “breaks down” is not its ability to give the correct answer, but the ability of the conceptual framework to give a clear explanation of what is going on, because it essentially defines measurement as “you know one when you see one”, which can lead to confusion.
(However, separately, I do feel the need to point out that “entanglement” is not at all a term that is related to measurement results per se, but rather to the state of a system before you measure it. In particular, if a system is entangled, you can (in principle) disentangle it by reversing whatever process you used to entangle it so that you no longer get correlations in the measurements.)
I don’t know, Many Worlds always led to more confusion than Copenhagen for me. But I suppose that’s a matter of taste since they’re equivalent.
As per the relationship between measurement and entanglement, from an empiricist viewpoint all quantum mechanical terms are related to measurement. If entanglement didn’t affect the outcome of measurements, it wouldn’t exist.
Indeed, you can disentangle an entangled system, which of course will change the outcome of measurements - that’s how you know it’s been disentangled.
I think to some extent we have been talking past each other. Very roughly speaking, I think that am more worried about what happens in the middle of an experiment, where you are more worried about what happens at the end. I actually completely agree with you that when a conscious being performs a measurement, then, from the perspective of that being, both interpretations of what happened when it performed the observation are equivalent. That is, the being has no way of telling them apart, and asking which interpretation is true at that point is, in my opinion, roughly along the same lines as asking whether the objective world exists.
(Just to be clear, it’s not my intent to get mystical here. I think of consciousness as essentially just being a way of processing information about the world, rather than positing the existence of souls.)
Interesting framing. But without measurements there isn’t really a need for different interpretations, is there? If that’s what you mean by “in the middle of an experiment”.
I will happily agree that before measurement, it’s very useful to think of the system as existing in many states at the same time.
Hmm, you could say it instead privileges the subjective experience over other types of interaction. There’s no reason in principle why you couldn’t experience every “world” at the same time, in the same way a measurement could in principle return all possible results at the same time.
But you don’t. Somehow your experience of reality is above unitary time evolution, even though “you” aren’t.
I agree completely that that the Copenhagen interpretation makes an excellent phenomenological model in simple (albeit, very common!) settings. However, the problem is that it breaks down when you consider experiments such as the “quantum eraser” (mentioned in other comments here), which causes people to tie themselves into intellectual knots because they are thinking too hard about exactly what is going on with measurement; once one deprivileges measurement so that it becomes just another kind of interaction, the seeming paradoxes disappear.
Copenhagen interpretation doesn’t break down for quantum erasure. Upon measurement you collapse the total quantum state into a result where the two measurements are consistent, that’s simply what entanglement means.
The timing of experiments, and the choice of what to measure, are elements ultimately irrelevant to the above statement, as the quantum erasure experiment demonstrates.
To clarify my imprecise language, what “breaks down” is not its ability to give the correct answer, but the ability of the conceptual framework to give a clear explanation of what is going on, because it essentially defines measurement as “you know one when you see one”, which can lead to confusion.
(However, separately, I do feel the need to point out that “entanglement” is not at all a term that is related to measurement results per se, but rather to the state of a system before you measure it. In particular, if a system is entangled, you can (in principle) disentangle it by reversing whatever process you used to entangle it so that you no longer get correlations in the measurements.)
I don’t know, Many Worlds always led to more confusion than Copenhagen for me. But I suppose that’s a matter of taste since they’re equivalent.
As per the relationship between measurement and entanglement, from an empiricist viewpoint all quantum mechanical terms are related to measurement. If entanglement didn’t affect the outcome of measurements, it wouldn’t exist.
Indeed, you can disentangle an entangled system, which of course will change the outcome of measurements - that’s how you know it’s been disentangled.
I think to some extent we have been talking past each other. Very roughly speaking, I think that am more worried about what happens in the middle of an experiment, where you are more worried about what happens at the end. I actually completely agree with you that when a conscious being performs a measurement, then, from the perspective of that being, both interpretations of what happened when it performed the observation are equivalent. That is, the being has no way of telling them apart, and asking which interpretation is true at that point is, in my opinion, roughly along the same lines as asking whether the objective world exists.
(Just to be clear, it’s not my intent to get mystical here. I think of consciousness as essentially just being a way of processing information about the world, rather than positing the existence of souls.)
Interesting framing. But without measurements there isn’t really a need for different interpretations, is there? If that’s what you mean by “in the middle of an experiment”.
I will happily agree that before measurement, it’s very useful to think of the system as existing in many states at the same time.