PES 106        Spring 2003
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General Astronomy II

Lecture Notes:

History of the Universe

text: Chapter 17 Sections 4 - 5

some references:

Anti-matter:

To understand the early stages of the Universe need to know about matter and anti-matter

anti-matter is just like matter - but has the opposite electrical charge

  • electron - negative charge
  • anti-electron = "positron" - positive charge

we can create matter from energy (E = mc2)

  • create a matter / anti-matter pair

we can create energy from matter (E = mc2)

  • annihilation = matter and anti-matter recombine to form radiation

protons and neutrons are all made up of smaller particles called "quarks" (anti-protons made up of anti-quarks)

History of the Universe

Radiation dominated Universe
  • up to about 1/2 million years old
  • universe dominated by high energy electromagnetic radiation
  • "light" collides frequently with matter
    • does not travel far so can not see through the universe (opaque)

Matter dominated Universe

  • after about 1/2 million years old
  • universe dominated by matter
  • radiation is now low energy
    • universe is "transparent"

History of the Universe

TIME
TEMPERATURE
COMMENTS

0 - 10-44 sec

.

Laws of Physics do not apply

10-44 - 10-35 sec

HOT !!! ... 1032 K

Forces Unified (more on this later)

10-35 - 10-32 sec

1027 K
  • Inflationary Model
  • rapid expansion of space (more on this later)

10-32 - 10-6 sec

1013 K
  • Universe dominated by radiation
  • quarks and anti-quarks form and annihilate one another
  • small excess of matter (1 part per billion)

10-6 - 1 sec

1010 K (10 billion degrees)

protons, anti-protons and neutrons form

1 - 5 sec

5 x 109 K (5 billion degrees)

electrons and anti-electrons form

3 -4 minutes

109 K (1 billion degrees)

nuclei of hydrogen, helium and lithium form

(about 76% Hydrogen, 24% Helium)

1/2 million years

5,000 K
  • Matter dominated Universe
  • neutral atoms form
  • gravity begins to cause clumping of matter

1 billion years ??

15 K

dark matter clumps - attracting ordinary matter into huge clouds

stars and galaxies begin to form

3 billion years

.

quasars dominate

10 - 20 billion years

3 K

NOW

100 billion years

.

galaxies break apart from collisions

1 trillion years

.
  • hydrogen is all consumed
  • stars die
  • Universe is white dwarfs, neutron stars, black holes and rocks

billion-billion-billion years ??

.

galaxies are giant black holes surrounded by dead stars

1031 years

.

galactic black holes merge

10100 years

.

black holes evaporate into particles and radiation

Here is a link to another timeline: http://www.pbs.org/wgbh/nova/universe/historywave.html

This interactive time-line looks at the history up to the Earth forming: http://origins.jpl.nasa.gov/poster/poster.html

Another timeline: http://www.cosmicvoyage.org/museum/h1c_cosmicclock.htm

Here is the history of the Universe and Earth compressed into a one year time period to give a sense of relative times: http://janus.astro.umd.edu/cgi-bin/astro/times.pl

Early Stages of the Universe: Inflation

Big Bang starts with hot matter and energy in a region the size of our solar system

What happened before that ?

Inflationary Period 

  • lasted about 10-32 of a second
  • space expands by a factor of about 1025 times
    • from a size much smaller than a proton
    • to the size of a softball

What causes the expansion?

Need to consider two ideas:
  • "negative" gravity
  • Unification of Forces

Negative gravity: - repulsive gravity (pushes matter apart)

would be possible under the conditions expected in the early universe

Four Forces of Nature:

  • gravity
    • long range
    • interaction of mass (and energy)
  • electromagnetic
    • long range
    • interaction of electrical charge
  • strong nuclear force
    • short range
    • hold nucleus together
  • weak nuclear force
    • short range
    • observed in radioactive decay

    At very high energies - these four all behave like ONE force (unification)

    VERY early universe may have had this unification

  • 10-43 seconds - gravity breaks away (other three still unified)
  • 10-35 seconds - strong nuclear force breaks away
  • 10-11 seconds - weak nuclear and electromagnetic forces separate

As forces separate: energy is released

Energy can be converted to mass

Mass is pushed apart by negative gravity

What else does the inflation model explain?

  • predicts slight imbalance between amount of matter and anti-matter
  • uniformity (smoothness) of cosmic microwave background radiation
    • extremely small size of universe means it was all the same
  • apparent "flatness" of universe
    • rapid expansion makes Universe appear flat
    • if you are on the surface of an inflated balloon - the area right around you "looks" flat

Other Universes??

Imagine our universe as starting as a tiny bubble that inflates inside of an expanding space

If other bubbles formed inside of expanding space, they could form other universes

Since everything is expanding - it is not possible to detect the other universes from our universe

MAYBE there are other universes independent of ours ?????

See Box Figure 17.2 [Link to Box Figure 17.2]

Changing views of the Universe:

from a Lecture delivered at the National Conference of the American Association for the Advancement of Science (AAAS) February, 2003 by Raymond Orbach, Director, Office of Science, Department of Energy.

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