2015/09/22 by Timothy Clifton, Clifton, Timothy
Physics and Astronomy · #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Relativity and Gravitational Theory #astro-ph.CO #gr-qc
paper · pdf · doi:10.48550/arxiv.1509.06682
6 pages. Contribution to the proceedings of MG14
arxiv created 2015/09/22 · openalex publication_date 2015/09/22 · arxiv updated 2015/09/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Almost all models of the universe start by assuming that matter fields can be modelled as dust. In the real universe, however, matter is clumped into dense objects that are separated by regions of space that are almost empty. If we are to treat such a distribution of matter as being modelled as a fluid, in some average or coarse-grained sense, then there a number of questions that must be answered. One of the most fundamental of these is whether or not the interaction energy between masses should gravitate. If it does, then a dust-like description may not be sufficient. We would then need to ask how interaction energies should be calculated in cosmology, and how they should appear in the Friedmann-like equations that govern the large-scale behaviour of the universe. I will discuss some recent results that may shed light on these questions.