Energy Requirement of Control: Comments on Szilard's Engine and Maxwell's Demon

TL;DR

This paper challenges common assumptions in the analysis of Szilard's engine and Maxwell's demon, showing that the energy required for control operations significantly exceeds the engine’s energy output, impacting interpretations of the Second Law.

Contribution

It provides a fundamental analysis of the energy costs of control mechanisms in Szilard's engine and Maxwell's demon, revealing higher dissipation than previously assumed.

Findings

Control-related entropy production exceeds the engine’s energy output.

Neglecting control energy costs leads to incorrect conclusions about thermodynamic laws.

Control operations generate more energy dissipation than the engine can compensate for.

Abstract

In mathematical physical analyses of Szilard's engine and Maxwell's demon, a general assumption (explicit or implicit) is that one can neglect the energy needed for relocating the piston in Szilard's engine and for driving the trap door in Maxwell's demon. If this basic assumption is wrong, then the conclusions of a vast literature on the implications of the Second Law of Thermodynamics and of Landauer's erasure theorem are incorrect too. Our analyses of the fundamental information physical aspects of various type of control within Szilard's engine and Maxwell's demon indicate that the entropy production due to the necessary generation of information yield much greater energy dissipation than the energy Szilard's engine is able to produce even if all sources of dissipation in the rest of these demons (due to measurement, decision, memory, etc) are neglected.