The Five Ages of the Universe : Inside the Physics of Eternity written by
and Greg Laughlin
posits that the Universe
can be divided into five ages
based on the predominant types of stars populating the Universe.
To do this the authors introduce the concept of a cosmological decade
Cosmological decades are logarithmic
in nature, so during cosmological
decade δ=5, the Universe is 10^5 or 100,000 years
old and during δ=30, the Universe is 10^30 or 1,000,000,000,000,000,000,000,000,000,000
The Primordial Era : δ = 0 to δ = 5
During this period from the Big Bang to 100,000 years, the basic
forces of nature separate and the basic building blocks of matter
appear, first baryons through baryosynthesis, then atomic nuclei
through nucleosynthesis and finally the elements hydrogen, helium and lithium
are formed by atomosynthesis.
The Stelliferous Era : δ = 6 to δ = 14
At the very beginning of this age galaxies are formed as quasars and
a large proportion of the first stars are born as hot blue supergiants which
quickly supernova and distribute matter which then becomes a second generation
of the wide variety of main sequence stars we are used to seeing in the night sky today.
We live in the middle of this age. Towards the end of this age, the majority of
stars use up the nuclear material that makes them shine and go nova to produce
stellar remnants such as white dwarfs, neutron stars, iron dwarfs or black holes.
Red dwarfs last the longest of any main sequence stars and slowly fade away.
At the end of this age, very few new stars are formed.
The Degenerate Era : δ = 15 to δ = 39
In this era, dark matter provides the energy that allows white dwarfs to
continue shining for trillions of years while most of the rest of the
Universe becomes darker and colder. Amongst the stellar remnants are Jovians
and brown dwarfs. Towards the end of this era, proton and neutron decay
destroy what is left of ordinary matter. By the end of this age, the only
objects of note in the Universe are black holes.
The Black Hole Era : δ = 40 to δ = 100
The black holes left during this era slowly evaporate due to Hawking radiation.
By the end of this era, the only particles left in the
Universe are leptons and photons.
The Dark Era : δ > 101
During this age, photons' wavelengths shift deep into the infrared to unimaginably
long wavelengths. The Universe is so large and so dark that any fundamental interaction
between any of these particles becomes increasingly rare. The authors believe that in this age,
the Universe could possibly undergo a phase transistion and start a new
Universe with a different set of laws of physics related to this Universe in a kind
of genetic code.