Information entropy and thermal entropy: apples and oranges

TL;DR

The paper clarifies that information entropy and thermodynamic entropy are fundamentally different, with no general interrelation, and highlights misconceptions and differences through physical examples and theoretical considerations.

Contribution

It demonstrates that information entropy does not have a general relation to thermodynamic entropy and can violate the Third Law of Thermodynamics.

Findings

No general interrelation between information and thermal entropy

Changes in information entropy depend on measurement resolution

Information entropy can violate the Third Law of Thermodynamics

Abstract

The frequent misunderstanding of information entropy is pointed out. It is shown that, contrary to fortuitous situations and common beliefs, there is no general interrelation between the information entropy and the thermodynamical entropy. We point out that the change of information entropy during measurement is determined by the resolution of the measurement instrument and these changes do not have a general and clear-cut interrelation with the change of thermal entropy. Moreover, these changes can be separated in space and time. We show classical physical considerations and examples to support this conclusion. Finally, we show that information entropy can violate the Third Law of Thermodynamics which is another indication of major differences from thermal entropy.