Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

# A Photon Force and Flow for Dissipative Structuring: Application to Pigments, Plants and Ecosystems

Version 1 : Received: 25 December 2021 / Approved: 27 December 2021 / Online: 27 December 2021 (15:59:20 CET)

How to cite: Michaelian, K.; Cano Mateo, R.E. A Photon Force and Flow for Dissipative Structuring: Application to Pigments, Plants and Ecosystems. Preprints 2021, 2021120440 (doi: 10.20944/preprints202112.0440.v1). Michaelian, K.; Cano Mateo, R.E. A Photon Force and Flow for Dissipative Structuring: Application to Pigments, Plants and Ecosystems. Preprints 2021, 2021120440 (doi: 10.20944/preprints202112.0440.v1).

## Abstract

Through a modern derivation of Planck's formula for the entropy of an arbitrary beam of photons we derive a general expression for the entropy production due to the irreversible process of the absorption of an arbitrary incident photon spectrum in material and its dissipation into an infrared-shifted grey-body emitted spectrum, the rest being reflected or transmitted. Employing the framework of Classical Irreversible Thermodynamic theory, we define the generalized thermodynamic flow as the flow of photons from the incident beam into the material and the generalized thermodynamic force is then just the entropy production divided by the photon flow which is the entropy production per unit photon at a given wavelength. We compare the entropy production under sunlight of different inorganic and organic materials (water, desert, leaves and forests) and show that organic materials are the greater entropy producing materials. Intriguingly, plant and phytoplankton pigments (including chlorophyll) have peak absorption exactly where entropy production through photon dissipation is maximal for our solar spectrum $430<\lambda<550$ nm, while photosynthetic efficiency is maximal between 600 and 700 nm. These results suggest that the evolution of pigments, plants and ecosystems has been towards optimizing entropy production rather than photosynthesis. We propose using the wavelength dependence of global entropy production as a biosignature for discovering life on planets of other stars.

## Keywords

disspative structuring; non-equilibrium thermodynamics; entropy production; origin of life; organic pigments; plants; ecosystems; evolution; chlorophyll; biosignatures

## Subject

PHYSICAL SCIENCES, Other

We encourage comments and feedback from a broad range of readers. See criteria for comments and our Diversity statement.

Views 0