All matter is in black holes, neutron stars, white dwarfs, brown dwarfs, and planets. 10 16-20 years . Collisions strip planets from stars, and eject stars from galaxies. Central black holes in galaxies grow. 10 14-20 years .
Binary stars spiral together and merge.
Collisions between white dwarfs produce supernovae. Collisions between brown dwarfs produce low mass stars. Typical galaxies shine with one solar luminosity. The only luminosity in the universe comes from white dwarfs absorbing dark matter. White dwarfs glow at a temperature of 64K. 10 33-37 years.