Title: quantum mechanics - Observer effect, do this mean literally someone or just any interaction with other matter? - Physics Stack Exchange
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Observer effect, do this mean literally someone or just any interaction with other matter?
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Content: The converse is true too, that if you measure it's position you have an inherent uncertainty in the momentum. I suggest looking up the double slit experiment if you would like a visual example of this. Many videos of this exist. Share
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answered Apr 11 '13 at 2:18
Steven Walton
Steven Walton
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You have touched on something of an unsolved problem in physics or philosophy of physics (depending on who you ask). It is not at all clear what counts as a 'measurement' of a quantum state. When quantum mechanics was first formulated, the authors started with the mathematical definition of a 'measurement', namely projecting the wavefunction of the system on to a certain eigenvector. Since then, there have been attempts to understand what (if any) physical acts correspond to this mathematical definition. We have come up with some cases where what we are doing, physically, clearly does fit the mathematical definition, but still have not found a rule for classifying all actions as either 'measurements' or 'not measurements'. I would say that the basic problem is that quantum mechanics is, at its core, a mathematical formalism. Trying to understand that formalism through intuition has always been a challenge and this includes understanding it through the concepts of language (like 'measurement' and 'observer').