🚀 go-pugleaf

mcirvin@husc8.harvard.edu (Mcirvin) writes:

>The commuting of observables at spacelike separation prevents
>spacelike communication via quantum entanglement precisely
>*because* the measurements act like eigenstate projectors.  An
>eigenstate of one such observable is always in an eigenspace of
>the other, so the order in which the projections occur doesn't
>matter, and there's no way one measurement can affect the result 
>of the other.

I have been a little imprecise; what I meant to say was that there's
no way that a measurement of one of the observables can indicate that
a measurement of the other has occurred.  Of course, the actual
eigenvalues measured can exhibit EPR correlations.  Sarfatti seems
to be saying that two observables can possess an uncertainty
relation even if the corresponding operators commute, which is
not something that happens if measurements correspond to projections
into eigenstates of the observables.
-- 
Matt McIrvin, professional gradgrind, amateur Usenet drifter