In this second part of our two-part paper we review and analyse attempts since 1950 to use information theoretic notions to exorcise Maxwell’s Demon. We argue through a simple dilemma that these attempted exorcisms are ineffective, whether they follow Szilard in seeking a compensating entropy cost in information acquisition or Landauer in seeking that cost in memory erasure. In so far as the Demon is a thermodynamic system already governed by the Second Law, no further supposition about information and entropy (...) is needed to save the Second Law. In so far as the Demon fails to be such a system, no supposition about the entropy cost of information acquisition and processing can save the Second Law from the Demon. (shrink)

Irreversibility, it is claimed, is a much broader concept than is entropy increase, as is shown by the occurrence of certain processes which are irreversible without seeming to involve any intrinsic entropy change. These processes include the spreading outwards into space of particles, or of radiation, and they also include certain biological and mental phenomena. For instance, the irreversible and treelike branching which is characteristic of natural evolution is not entropic when it is considered in itself—i.e. in abstraction from accompanying (...) biochemical and physiological activity. What appears to be the common feature of all forms of irreversibility is the fanning out of trajectories, new entities or new states, in the temporal direction towards the future. (shrink)