March 5, 2025: HiPHis Conference – Modeling in physics: a story of scales

Wednesday, March 5, 2025, from 3:30 p.m. to 5:30 p.m., UM Faculty of Science, lecture hall A-5.04, free admission
(building 5 – Triolet campus)

Modeling in physics: a story of scales

  Annick Lesne
Theoretical physicist, CNRS Senior Researcher at LPTMC Paris-Sorbonne and IGMM Montpellier

Abstract
The starting point for this presentation is to show how understanding a real system using models depends fundamentally on the scales at which it is observed, those of the phenomena we wish to predict, and the intrinsic characteristic scales of the system. I will illustrate this point with several examples that are now considered classic: diffusion processes, the DNA molecule, and the coast of Brittany. We will see that this perception of different scales is put to the test for fractal structures and, more generally, for systems exhibiting scale invariance; and conversely, how the detection of scale invariance is limited by the scales of observation. Clearly distinguishing between different scales and levels of organization is also essential for considering the concept of emergence and studying the complex systems in which it manifests itself, such as a crowd or a dune.

Selective bibliography:
□ Lesne A., Laguë M. (2008), L’invariance d’échelle – des changements d’états à la tubulence, Belin, Paris.
□ Stanley H.-E., Stauffer D., Lesne A. (1999), Physics Course – From Newton to Mandelbrot, Springer France.
□ Bourgine P., Lesne A. (2006), Morphogenesis – The Origin of Forms, Belin, Paris.

A theoretical physicist specializing in renormalization and scale invariance, Annick Lesne is a Research Director at the CNRS and is affiliated with both the Laboratory of Theoretical Physics of Condensed Matter in Paris (LPTMC, UMR 7600 CNRS, Sorbonne University Jussieu) and the Institute of Molecular Genetics in Montpellier (IGMM UMR 5535 CNRS). Annick Lesne is also Deputy Scientific Director at the CNRS National Institute of Physics (where she is responsible for the MITI Mission for Transversal and Interdisciplinary Initiatives). She is also involved in the philosophy of science and the connections between science and the arts, and has written several books on teaching and popularizing her field of research.

Conference associated with the Physics Teaching Department of the Faculty of Sciences of Montpellier