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

May 24, 2022, 11:36 AM
23m

Speaker

Fei Huang (ITP CAS and UC Irvine)

Description

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, we point out that this lore is not always correct, and that it is possible to obtain a form of “stasis” in which the relative cosmological abundances $\Omega_i$ of the different components remain unchanged over extended cosmological epochs, even as the universe expands. Moreover, we demonstrate that such situations are not fine-tuned, but are actually 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. The existence of this kind of stasis therefore gives rise to a host of new theoretical possibilities across the entire cosmological timeline, ranging from potential implications for primordial density perturbations, dark-matter production, and structure formation all the way to early reheating, early matter-dominated eras, and even the age of the universe.

Primary author

Fei Huang (ITP CAS and UC Irvine)

Co-authors

Brooks Thomas Keith Dienes (University of Arizona) Tim M.P. Tait (University of California, Irvine) Doojin Kim (Texas A & M University (US)) Lucien Heurtier (IPPP, Durham, England)

Presentation materials