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 Sciences, Lecture Hall A-5.04, free admission
(Building 5 – Triolet Campus)

Modeling in Physics: A Story of Scales

  Annick Lesne
Theoretical physicist, CNRS Research Director at the LPTMC Paris-Sorbonne and the IGMM Montpellier

Abstract
The starting point of this presentation is to show how our understanding of a real system using models depends fundamentally on the scales at which we observe it, on the scales of the phenomena we wish to predict, and on the system’s intrinsic characteristic scales. I will illustrate this point using several now-classic examples: diffusion processes, the DNA molecule, and the Brittany coastline. 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 understanding the concept of emergence and studying the complex systems where it manifests, such as a crowd or a dune.

Selected Bibliography:
□ Lesne A., Laguë M. (2008), Scale Invariance: From Phase Transitions to Turbulence, 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.

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

Adjunct Professor in the Department of Physics Education, Faculty of Sciences, Montpellier