The History of the Universe:
Time after Big Bang: Event:
< 1 s, T = 1 x 10 K2 - All types of elementary particles in existence.
1000 Particle transmutations occur.
4 s. -Matter and anti-matter begin annihilation to
produce energetic photons.
*NOTE: NO SPACE MEANS NO TIME! REPORT TOPICS: BIG MASSIVE
BLACKHOLES AND HAWKING RADITATION.
3 Minutes. -Neutrons and protons fuse to form Helium
30 Minutes. -Elementary particle transmutations cease.
380,000 years, T = 3000 K -Recombination Era = photon energies have
declined enough such that Hydrogen and Helium
ATOMS can survive.
1 x 10 years. -Galaxies form.
2 x 10 years. -Stars form.
[?] Years. -Present time = Age of the Universe.
The Age of the Universe: Hubble Time:
Recall the Hubble Law:
V r H dowhere we use a Hubble parameter of 75 km/s
Recall that d = Vt and replace d in above equation:
V = H ot
1 = H o
t = 1/Ho= Hubble time = Age of Universe.
t = 1 = t = Mpc
75 km/s 75 km/s
= t = 3.09 x 10 km = t = 4.12 x 10 s = t =13.1 x 10 years.
*NOTE: TODAY IT IS = t = 13.8 x 10 years. Open Universe: Density of matter is low = gravity is weak = universe expands forever.
Closed Universe: Density of matter is high = gravity will halt the expansion and re-
contract the universe. If this happens repeatedly, we have an oscillating universe.
Flat Universe: Universe contains the so-called Critical density of matter = galaxies
barely manage to AVOID re-collapse.
Future of an Open or Flat Universe:
Time after Big Bang: Situation:
1) 1 x 10 years. -Hydrogen and Helium are depleted so that no new
stars can form.
2) 1 x 10 years. -Existing stars run out of fuel.
3) 1 x 10 years. -All stars will have experienced ~100 disruptive
encounters, flinging their planets into space.
4) 1 x 10 years. -Evaporations of stars and collapse of galaxies into
black holes at their centers.
30 + +
5) 1 x 10 years. -Protons decay (???). p = e + v (a positron and
6) 1 x 10 100years. –Hawking = Black Holes decay.
7) Far Future. -The Big Frizzle = an ever-expanding gas of
electrons, protons, neutrons, photons.
Future of a Closed or Oscillating Universe:
1) The expansion phase is the same as statements.
a) Though 5. Above.
2) At some unknown future time, re-contraction begins. Faraway groups of galaxies become
blue-shifted, the density of the universe increases, black holes increase in