Matter is one of the contributors to the density of the universe. The main property of matter is that it is localised and pointlike, keeping a constant energy, so as a realmverse expands the energy density of matter will drop off as a-3.
More generally, in an n-dimensional universe, the energy density of matter will drop off as a-n.
If matter does not interact electromagnetically, then it is called dark matter.
|Density Species Types|
|Phantom energy · Cosmological constant |
Matter · Radiation · Ultralight