  Although nondemolition, reliable, and instantaneous quantum measurements of
some nonlocal variables are impossible, demolition reliable instantaneous
measurements are possible for all variables. It is shown that this is correct
also in the framework of the time-symmetric quantum formalism, i.e. nonlocal
variables of composite quantum systems with quantum states evolving both
forward and backward in time are measurable in a demolition way. The result
follows from the possibility to reverse with certainty the time direction of a
backward evolving quantum state. Demolition measurements of nonlocal backward
evolving quantum states require remarkably small resources. This is so because
the combined operation of time reversal and teleportation of a local backward
evolving quantum state requires only a single quantum channel and no
transmission of classical information.
