Читать книгу Cyber-physical Systems - Pedro H. J. Nardelli - Страница 31

The Maxwell's demon thought experiment can be analyzed as a hypothetical system. The idea here is to provoke the reader to think about this procedure and be critical about it. Different from the other examples, we are dealing with something that does not and cannot exist in the real world like a car or a wind turbine. On the other hand, possible ways to realize this thought experiment have been presented in the literature, although this will not be our focus now. In the following, we propose the demarcation of the Maxwell's demon experiment as a system, indicating what this particular system, its PF, and its conditions of existence are as such.

1 PS (a) Structural components: a completely isolated box with a door that can open and close in an ideal way, (b) operating components: the demon who controls the door; and (c) flow components: a gas with equal temperature composed of molecules moving at different speeds.

2 PF Decrease the entropy of the system assuming no exchange of energy between it and its outside.

3 C1 It is physically possible to decrease the entropy of an isolated system (i.e. violating the second law of thermodynamics).

4 C2 The demon needs to know the velocity of the particles, their positions, and the sides that are associated with “cold” and “hot” states in order to control the door without using energy aiming at a decrease in the system entropy.

5 C3 The system has no relation to the environment (no flow of energy, matter, or information); therefore, this condition can be excluded.