EPR paradox, 11.1

Black hole information paradox, 2.2.1



~ lack of the existence of measuring device in the definition of the experimental setup to define the difference between microscopic events in terms of the difference between observable physical events

— Me@2022-01-31 08:33:01 AM


Note that superposition is mathematical, not physical. A wave function is not probabilities, nor a physical wave. Superposition applies only to wave functions, not to probabilities, nor to physical realities.

If superposition had been of probabilities or of physical realities, there would have been no interference patterns in the double-slit experiment.

— Me@2022-02-11 03:32:47 PM


For example, in the double-slit experiment, if no detector is installed, the system is in a quantum superposition state.

It is not that each individual photon is in a superposition, because an individual particle has no 100% objective identity, due to the indistinguishability of identical particles. Instead, it is that the system of the whole experimental setup is in a superposition.

This applies also to other more complicated experimental setups, such the EPR experiment, the delayed-choice experiment, the delayed-choice quantum eraser, etc.

— Me@2021-01-23 12:57 AM

— Me@2022-02-11 03:29 PM


physical definition

~ define the microscopic events in terms of observable physical phenomena such as the change of readings of the measuring device

~ define unobservable events in terms of observable events

— Me@2022-01-31 08:33:01 AM


a definite state

~ an eigenstate

~ a state that has given a physical definition

— Me@2022-02-11 01:19:57 PM


What we do in the present does not change the past, but changes we can see/say about the past. — Wheeler on Delayed choice quantum eraser, paraphrased, Me@2018-02-04 03:40:27 PM

Physics is not about reality, but about what one can say about reality. — Bohr, paraphrased

Physics should deduce what an observer would observe, not what it really is, for that would be impossible. — Me@2018-02-02 12:15:38 AM

It is because, tautologically, any state that cannot be physically defined is logically and physically meaningless.

In other words, any state that has no distinguishing observable effects does not make sense. For example, if in a double-slit experiment, no detector is allowed, then it is no point to label the state either as “go-left” or as “go-right”. Instead, we have to label the state as a superposition state.

Some unobservable (aka microscopic) variables are meaningless. It is not because of any philosophical points of view, but because we have not defined those variables in terms of observables or observable events, aka physical phenomena. In other words, those variables have no physical definitions yet.

— Me@2022-02-11 03:50:59 PM


Quantum mechanics, and physics in general, gives the rules of storytelling about reality. A story is a post hoc description of a physical event. In other words, quantum mechanics, and physics in general, is about phenomena, not noumena.

phenomenon (plural phenomena)

~ thing appearing to view

~ reality with respect to an observer

noumenon (plural noumena)

~ thing-in-itself

~ reality independent of any observers

— Me@2022-02-11 3:00 PM



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