- #1
cdog1350
- 4
- 0
One of the postulates of QM is that the physical state of any system (with any number of constituent particles) corresponds to a Hilbert state vector ψ. So an isolated system that includes an object to be observed, the observing apparatus, and also the human observer himself is also represented by some state vector ψ.
This state evolves in time according to the Schrodinger equation, no matter what the internal interactions of the objects in the system are. An observer performing a measurement on an object is just such an internal interaction (between the particles making up the object+apparatus+observer), and does not mark or signify anything special happening to the state vector - certainly not a 'collapse' of any kind.
But according to the orthodox interpretation of QM, after the measurement the state of the system collapses to an eigenvector A[itex]_{n}[/itex] of the observable operator.
Both the uncollapsed state ψ' and the collapsed A[itex]_{n}[/itex] are then valid states of the system according to this interpretation. Since ψ' and A[itex]_{n}[/itex] give different predictions for measurements, we must conclude that they are subjective states - i.e. states relative to some observer. For an observer outside the system, the state is ψ', but for the observer inside the system, the state is A[itex]_{n}[/itex].
But this means that the orthodox statement of QM theory explicitly postulates a special status for the human observer! In other words, the state describing the system depends on who will be doing the measurement (someone inside or someone on the outside), and so can not be talked about without reference to a specific observer. Not only that, but because the state is subjective, then reality (by "reality" I mean the description predicting results of measurements made in the future) will also be subjective. If we say that only one reality actually exists (multiple realities would be the MWI interpretation), then the conclusion is that only one observer actually exists. In other words, orthodox QM implies solipsism.
Is this the necessary conclusion, or is an objective reality somehow possible under that interpretation?
This state evolves in time according to the Schrodinger equation, no matter what the internal interactions of the objects in the system are. An observer performing a measurement on an object is just such an internal interaction (between the particles making up the object+apparatus+observer), and does not mark or signify anything special happening to the state vector - certainly not a 'collapse' of any kind.
But according to the orthodox interpretation of QM, after the measurement the state of the system collapses to an eigenvector A[itex]_{n}[/itex] of the observable operator.
Both the uncollapsed state ψ' and the collapsed A[itex]_{n}[/itex] are then valid states of the system according to this interpretation. Since ψ' and A[itex]_{n}[/itex] give different predictions for measurements, we must conclude that they are subjective states - i.e. states relative to some observer. For an observer outside the system, the state is ψ', but for the observer inside the system, the state is A[itex]_{n}[/itex].
But this means that the orthodox statement of QM theory explicitly postulates a special status for the human observer! In other words, the state describing the system depends on who will be doing the measurement (someone inside or someone on the outside), and so can not be talked about without reference to a specific observer. Not only that, but because the state is subjective, then reality (by "reality" I mean the description predicting results of measurements made in the future) will also be subjective. If we say that only one reality actually exists (multiple realities would be the MWI interpretation), then the conclusion is that only one observer actually exists. In other words, orthodox QM implies solipsism.
Is this the necessary conclusion, or is an objective reality somehow possible under that interpretation?