The Disordered Universe 2025: An Intro and a Vision

Abstract

The Disordered Universe is a novel research direction that exploits ideas and techniques coming from apparently unrelated research areas, ranging from cosmology to scattering amplitudes in particle physics and disordered complex systems, with the aim of addressing open questions in cosmology at all scales, from the very infra-red (or very late time) to the early universe. This paper acts as a general introduction and vision for a set of lectures delivered at the first La Ricotta Summer School "The Disordered Universe 2025", held from 21 July to 10 August 2025. These lectures involved open quantum systems, analytic properties of scattering amplitudes and correlation functions, foundations and quantum aspects of the de Sitter universe, as well as statistical physics out of equilibrium and spin glasses. While the lecture notes related to each course taught at the school will be published separately and are inevitably devoted to both conceptual and technical aspects of each of these topics, the school was not meant to be a collage of independent topics: the present paper has the purpose of outlining the global vision, how cosmology ends up being a unifier and benefits from both their viewpoint and techniques, how all the concepts and techniques originally coming from these four different areas are part of the same cosmological narrative, why this point of view deserves to be explored, and drawing perspectives for the future. We consider it crucial to build a microscopic theory for the early universe and maybe one that embraces all scales.