On burning a lump of coal

Understand

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.