“Stasis, Stasis, Stasis”

Many theories of physics beyond the Standard Model give rise to a surprising early-universe cosmology during which the abundances of different energy components such as matter, radiation, and vacuum energy remain constant across extended cosmological eras, even though the universe is expanding.  Even more surprisingly, such “stasis” epochs are actually universal attractors, with the universe necessarily entering (and later exiting) such epochs for a wide variety of initial conditions.  In this talk, I will provide a theoretical overview of the stasis phenomenon and discuss some of its implications and applications.   These stretch 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.  My focus in this talk will be on the theoretical underpinnings of the stasis phenomenon.  A related talk by Prof. Brooks Thomas (Lafayette College) on Thursday, Sept. 19 will focus on particular model realizations of stasis, the observational signatures to which stasis can lead, and a possible connection between stasis and cosmic inflation.   As we shall see, the stasis phenomenon greatly expands the range of theoretical and phenomenological possibilities for the physics of the early universe.