# Tag Info

## New answers tagged measurement-problem

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A measurement is a form of interaction. A's interaction with the state is information that B is not unaware of. Which is equivalent to say that A's interaction is information that B cannot use. Thus, your two statements are equivalent in that the best B can do is use the information about the state that he does have to make a prediction. A practical ...

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It shouldn't make a difference because in both cases the particle is measured. This kind of question can be rather muddy - physicists try to stay away from using the words 'observer' and 'measurement' in quantum mechanics because they raise more questions than they answer. At any rate, most physicists prefer 'interaction with a macroscopic system'.

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To summarize, assume hypothetically we managed to find a way in the future where we can have a look at an electron without disturbing it by measurement or causing its wave function to collapse, would the uncertainty principle still hold in such a case?? Why/Why not? To start with any measurement when looked at the quantum mechanical level involves ...

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But in practice, is there any measurement that will NOT disturb the system at all? To prove that uncertainty is beyond measurement, we must design a measurement process that does not disturb the system. If such a process cannot be designed then the statement that "uncertainty is beyond measurement" cannot be experimentally tested. Isn't it? I don't know ...

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No, it doesn't collapse to an eigenstate. Collapse to an eigenstate is a picture of an ideal measurement. In general the final state will not be describable by a wave function, because it's not a pure state, it is instead a mixed state. See this question, which is about inexact measurements. Position eigenstate in position representation is $\langle ... 0 No. Position operator does not have normalizable eigen-functions ($\delta(x-x_0)\$ is not normalizable). The closest thing one can do in this formalism is to contract the wave function to some sharp peak with non-zero width and finite height, based on the accuracy of the measurement. With continuous space, particle cannot be in an "eigenstate of position", ...

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It is due to the nature of quantum mechanics. In classical regime, the lowest possible energy is zero. But in QM, the lowest state(ground state) still has energy. Quantum nature is wave-nature. In CM, you can pinpoint a location of an object but in QM, it is a distribution (probability density). What you can only do is find the smallest distribution not a ...

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