CONSISTENT USE OF PARADOXES IN DERIVING CONSTRAINTS ON THE DYNAMICS OF PHYSICAL SYSTEMS AND OF NO-GO THEOREMS

The classical methods used by recursion theory and formal logic to blo ck paradoxes do not work in quantum information theory. Since quantum information can exist as a coherent superposition of the classical ''y es'' and ''no'' states, certain tasks which are not conceivable in the classical setting can be performed in the quantum setting. Classical logical inconsistencies do not arise, since there exist fixed point st ates of the diagonalization operator. In particular, closed timelike c urves need not be eliminated in the quantum setting, since they need n ot lead to the classical antinomies. Quantum information theory can al so be subjected to the treatment of inconsistent information in databa ses and expert systems. It is suggested that any two pieces of contrad icting information are stored and processed as coherent superposition. In order to be tractable, this strategy requires quantum computation.