Jul 16 – 26, 2022
US/Pacific timezone

Stasis in an Expanding Universe: A Recipe for Stable Mixed-Component Cosmological Eras

Jul 18, 2022, 7:00 PM
2h 20m
211 South Ballroom (HUB)

211 South Ballroom



Brooks Thomas (Lafayette College)


One signature of an expanding universe is the time-variation of the cosmological abundances of its different components. For example, a radiation-dominated universe inevitably gives way to a matter-dominated universe, and critical moments such as matter-radiation equality are fleeting. In this talk, I shall demonstrate that this lore is not always correct. In particular, I shall show how a form of "stasis" can arise wherein the relative cosmological abundances of the different components remain unchanged over extended cosmological epochs, even as the universe expands. Moreover, I shall also demonstrate that such situations are not fine-tuned, but are in fact global attractors within certain cosmological frameworks, with the universe naturally evolving towards such long-lasting periods of stasis for a wide variety of initial conditions. I shall also discuss some of the implications of a stasis epoch for the evolution of primordial density perturbations and the growth of structure, for dark-matter production, and even for the age of the universe.

In-person or Virtual? Virtual

Primary author

Brooks Thomas (Lafayette College)


Keith Dienes (University of Arizona) Fei Huang ( ITP CAS and UC Irvine) Lucien Heurtier (IPPP, Durham, England) Doojin Kim (Texas A & M University) Tim Tait (UC Irvine)

Presentation materials