2007/03/28 by Robert J. Nemiroff, Nemiroff, Robert J. · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics (astro-ph) #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Earth Systems and Cosmic Evolution #FOS: Physical sciences #Relativity and Gravitational Theory #Space Science and Extraterrestrial Life
paper · pdf · doi:10.48550/arxiv.astro-ph/0703737
openalex publication_date 2007/03/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Might stable energy species "lighter" than radiation, with w > 1/3, exist?\nA dimensional expansion of the cosmological Friedmann Equation of energy has a\nclear place for them. Such energies would affect the universe much differently\nthan dark energies, and so are here dubbed "ultralight." As the universe\nexpands, ultralight dilutes even faster than light. Although any specie of\nenergy can be mimicked by a properly evolving scalar field, ultralight energy\nspecies are hypothesized here to be stable and not related to dynamics of a\nscalar field. Ultralight is not considered a candidate to make a significant\ncontribution to the energy budget of the universe today, although ultralight\nmight have affected the universe in the distant past. In particular, the\nw=2/3 ultralight energy specie appears to have relatively mundane physical\nattributes. A discussion of properties and falsifiable attributes of ultralight\nis given. The duration of primordial nucleosynthesis is extrapolated to limit\nthe present density of w=2/3 ultralight to below one part in 100 billion of\nthe critical density.\n