Laboratory rivers extremize friction and are cosmological analogues
Geophysics
2026-05-15 v1 General Relativity and Quantum Cosmology
Abstract
In the shallow water approximation, the cross-sectional profiles of laboratory rivers satisfy a differential equation here shown to be formally the Friedmann equation of cosmology ruling the evolution of Anti-de Sitter universe. The ensuing cosmic analogy provides a counterintuitive Lagrangian for the transverse river profile. Extremizing the corresponding action corresponds to extremizing the friction force on the river bottom and the energy dissipation rate. Analysis of the second variation establishes that this extremum is a maximum.
Keywords
Cite
@article{arxiv.2605.14670,
title = {Laboratory rivers extremize friction and are cosmological analogues},
author = {Valerio Faraoni and Nikki Veilleux},
journal= {arXiv preprint arXiv:2605.14670},
year = {2026}
}
Comments
8 pages, LaTeX