On the Supposed Mass of Entropy and That of Information

Abstract

In the theory of special relativity, energy can be found in two forms: kinetic energy and rest mass. The potential energy of a body is actually stored in the form of rest mass, the interaction energy too, but temperature is not. Information acquired about a dynamical system can be potentially used to extract useful work from it. Hence, the “mass–energy–information equivalence principle” that has been recently proposed. In this paper, it is first recalled that for a thermodynamic system made of non-interacting entities at constant temperature, the internal energy is also constant. So, the energy involved in a variation in entropy (TΔS) differs from a change in the potential energy stored or released and cannot be associated to a corresponding variation in mass of the system, even if it is expressed in terms of the quantity of information. This debate gives us the opportunity to deepen the notion of entropy seen as a quantity of information, to highlight the difference between logical irreversibility (a state-dependent property) and thermodynamical irreversibility (a path-dependent property), and to return to the nature of the link between energy and information that is dynamical.

Thermostatistics, Information, Subjectivity: Why Is This Association So Disturbing?

“…In this sense, entropy and information remain even more elusive concepts than that of potential energy. But developing this point deserves another article [99].…”

Landauer Bound in the Context of Minimal Physical Principles: Meaning, Experimental Verification, Controversies and Perspectives

“…Objections and criticism of the Landauer principle are discussed [103,104,109]. The massenergy-information equivalence principle was criticized recently [116]. Therefore, a lot of questions related to the Landauer principle and its extensions remain debatable.…”

“…The mass-energy-information equivalence principle, summarized by Equations ( 19) and (20), was criticized recently [116]. In particular, Lairez argued that (i) isothermal variation in the entropy-rooted part of the free energy of a body (namely, T∆S) is not accompanied by any variation in its mass, (ii) the Landauer-Bennet idea is not a general principle and is only true in a particular case, and (iii) the link between information and energy is valid only for fresh information about a dynamic system.…”

“…In particular, Lairez argued that (i) isothermal variation in the entropy-rooted part of the free energy of a body (namely, T∆S) is not accompanied by any variation in its mass, (ii) the Landauer-Bennet idea is not a general principle and is only true in a particular case, and (iii) the link between information and energy is valid only for fresh information about a dynamic system. Old information, or information detached from its subject matter, is no longer information and has no value [116]. Thus, the physical groundings of the link between the mass, energy, and information remain debatable and should be clarified.…”