THE IMPOSSIBILITY OF ACCURATE STATE SELF-MEASUREMENTS

It is shown that it is impossible for an observer to distinguish all p resent states of a system in which he or she is contained, irrespectiv e of whether this system is a classical or a quantum mechanical one an d irrespective of whether the time evolution is deterministic or stoch astic. As a corollary, this implies that it is impossible for an obser ver to measure the EPR-correlations between himself or herself and an outside system. Implications of the main result are discussed for how we have to conceive of universally valid theories.