On burning a lump of coal

TL;DR

Burning a lump of coal in a blackbody furnace produces an emission spectrum with an entropy transfer of about 3.9 bits per photon, revealing an underappreciated informational aspect of standard quantum thermodynamics.

Contribution

This paper quantifies the entropy and information transfer during burning, linking unitarity and blackbody radiation in a novel way.

Findings

Emission spectrum approximates Planck distribution

Average entropy transfer is approximately 3.9 bits per photon

Entropy/information budget of burning is quantitatively characterized

Abstract

Burning something, (e.g. the proverbial lump of coal, or an encyclopaedia for that matter), in a blackbody furnace leads to an approximately Planck emission spectrum with an average entropy/information transfer of approximately $3.9 \pm 2.5$ bits per emitted photon. This quantitative and qualitative result depends only on the underlying unitarity of the quantum physics of burning, combined with the statistical mechanics of blackbody radiation. The fact that the utterly standard and unitarity preserving process of burning something (in fact, burning anything) nevertheless *has* an associated entropy/information budget, and the quantitative *size* of that entropy/information budget, is a severely under-appreciated feature of standard quantum statistical physics.