Adventures in Friedmann cosmology: A detailed expansion of the cosmological Friedmann equations
Abstract
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, perfectfluid 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 littlediscussed 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.
 Publication:

American Journal of Physics
 Pub Date:
 March 2008
 DOI:
 10.1119/1.2830536
 arXiv:
 arXiv:astroph/0703739
 Bibcode:
 2008AmJPh..76..265N
 Keywords:

 04.00.00;
 General relativity and gravitation;
 Astrophysics
 EPrint:
 35 pages, 4 tables, comments solicited