2007/03/28 by Robert J. Nemiroff, Bijunath Patla, Bijunath R. Patla · 1 voice · 1 citation
Physics and Astronomy · #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1119/1.2830536
arxiv published 2007/03/28 · arxiv updated 2007/12/14 · openalex publication_date 2008/02/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
The general relativistic cosmological Friedmann equations, which describe how the scale factor of the universe evolves, are expanded explicitly to include energy forms not usually seen. The evolution of the universe as predicted by the Friedmann equations when dominated by a single, isotropic, stable, static, perfect-fluid energy form is discussed for different values of the gravitational pressure to density ratio w. These energy forms include phantom energy (w<−1), cosmological constant (w=−1), domain walls (w=−2∕3), cosmic strings (w=−1∕3), normal matter (w=0), radiation and relativistic matter (w=1∕3), and a previously little-discussed form of energy called “ultralight” (w>1∕3). A brief history and possible futures of Friedmann universes dominated by a single energy form are discussed.