- #1
clacker
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Question about measuring observables. If have 2 particle system the particle seperation
Q=x1-x2 and total momentum P=p1+p2 are observables of the system as a whole and are
commuting. How do you measure these observables. It would seem the only way to
measure the separation is to measure the individual particle positions x1,x2 and subtract
them. With the total momentum you measure the particle momentum's seperately and add.
However, since Q,P commute you should be able to measure Q,P simultaneously. But if do
it by measuring individual particle properties you have violated uncertainty principle since
you have both position and momentum for each particle. So is there some way to measure
Q or P without determining x1 and x2 or p1 and p2 or are Q and P nonmeasurable and only really mathematical fictions.
Q=x1-x2 and total momentum P=p1+p2 are observables of the system as a whole and are
commuting. How do you measure these observables. It would seem the only way to
measure the separation is to measure the individual particle positions x1,x2 and subtract
them. With the total momentum you measure the particle momentum's seperately and add.
However, since Q,P commute you should be able to measure Q,P simultaneously. But if do
it by measuring individual particle properties you have violated uncertainty principle since
you have both position and momentum for each particle. So is there some way to measure
Q or P without determining x1 and x2 or p1 and p2 or are Q and P nonmeasurable and only really mathematical fictions.