Thermalization of nearly integrable lattices (FPUT)
This text mentions work from 2024 on. Those parts were partly written without a live literature search and have not been checked by an editor yet.
In 1955 Fermi, Pasta, Ulam and Tsingou simulated a chain of weakly nonlinear springs expecting energy to spread evenly among all vibration modes, and found it kept returning to where it started. How long such nearly solvable systems take to reach thermal equilibrium, and whether they always do, is still being settled.
Why it matters
It tests the basic assumption of statistical mechanics that weak interactions are enough to bring a large system to thermal equilibrium.
Review
W. Fu, Z. Wang, W. Lin, D. He, J. Wang, Y. Zhang, H. Zhao, The Fermi-Pasta-Ulam-Tsingou problem after 70 years: toward universal laws of thermalization in lattice systems in the thermodynamic limit, arXiv, 2026. https://arxiv.org/abs/2603.23347 reference checked
See also
Timestamp record
- Signed record
- b026e7f128af…
- Public log
- Entry 352, in checkpoint 2,123
- In the log by
- Block 969,698, 2026-10-03
This text was in the PubPhys log by that date. The date says nothing about when the problem was first posed.