Define
time by “cosmic decade”: time=10 t years
(t is decade)
t = -50: Planck epoch
t = -35: symmetry breaking, inflation
t = -12: formation of “normal” particles
t = -6 : production of helium
t = 4 : end of radiation domination
t = 5.5: atoms form, cosmic microwave background
t = 6 : first stars form
t = 9 : Milky Way, galaxies form
t = 9.5: formation of solar system
t =10.2: Sun dies
t = 14 : end of star formation, smallest stars die
t = 16 : colliding brown dwarfs
t = 19 : most brown dwarfs, planets kicked out of galaxies
t = 30 : remaining dwarfs fall into central black hole
t = 37 : free protons decay, neutron stars decay
t = 39 : protons in dwarfs and planets decay
t = 42 : dark matter particles decay into photons
t = 66 : stellar black holes evaporate
t = 84 : galactic black holes evaporate
t = 98 : largest black holes evaporate
t = 141 : last positronium decays
(see
“The Five Ages of the Universe” by Adams and Laughlin)