The Disordered Universe

This book offers the first comprehensive introduction to a new research direction in fundamental physics that seeks to understand the origin and evolution of the universe. It brings together perspectives and tools from four distinct areas: quantum open systems, scattering amplitudes in particle physics, de Sitter physics, and disordered systems in statistical mechanics. In particular, it explores the open system approach to simple effective field theories, inflation, gauge theory and gravity, and the construction of quantum field theories in expanding universes. Topics include the Landau analysis of Feynman integrals in both particle physics and cosmology, the structure of Hilbert spaces in curved spacetimes, and the interplay between Lorentzian and Euclidean formulations of computables. The book also delves into the physics of the glass transition, with a detailed treatment of spin glass models and their relevance to understanding the state space in cosmology, highlighting how disorder and complexity inform our grasp of the universe’s large-scale behavior. Based on lectures delivered by leading experts at the summer school The Disordered Universe 2025 , held in As Barreiras (Castro Caldelas, Spain) from 21 July to 01 August 2025, the book is designed for graduate students and early-career researchers. Each chapter includes both the lecture content and accompanying tutorial sessions, providing a pedagogical and hands-on approach to the material. Readers are expected to have a foundational understanding of quantum field theory, general relativity, cosmology, complex analysis, and statistical physics. By integrating diverse theoretical frameworks, this book opens new pathways for exploring cosmological phenomena and offers a valuable resource for those interested in the frontiers of theoretical physics.