Nobel Prize in Physics in 2021 2026-10-18
Syukuro Manabe and Klaus Hasselmann each received one quarter for physical climate models quantifying variability and predicting global warming. Giorgio Parisi received one half for discovering how disorder and fluctuations interact in physical systems from atomic to planetary scales.[ref]
https://www.nobelprize.org/prizes/physics/2021/summary/. Individual laureate entries, quarter/quarter/half shares and two distinct award contributions
Replica symmetry breaking 2026-10-18
Giorgio Parisi's 1979 work replaced a single replica order parameter by an infinite hierarchy in the mean-field theory of spin glasses. The claim concerns a thermodynamic model, rather than inequivalence of the labels attached to two finite laboratory copies.[ref]
Infinite Number of Order Parameters for Spin-Glasses by Giorgio Parisi. Abstract, 3 December 1979: an infinite number of order parameters in mean-field replica theory
For equilibrium states with weights and local means , define . The distribution records their similarities. This state-based overlap distribution is distinct from the finite instantaneous spin overlap used in the triangle example.[ref]
Nobel Lecture: Multiple equilibria by Giorgio Parisi. §V, equations (12)–(14), overlaps between equilibrium states and their sample-dependent distribution