The Big Bang and Cosmology
A look at how our universe began
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Objectives
• To explain how our universe was
born
• To explain and cite the 4 pieces
of evidence for the big bang
theory.
What is the Big Bang Theory?
• 13.7 billion years ago, the
universe was a ball of
energy & matter, that was
very, very small
• The early universe was
very hot and densely
packed with matter
• An explosion happened.
Mass and energy were
sent moving away from
that central point.
• During the explosion,
Hydrogen and Helium
were made.
Evidence for the Big Bang Theory
1) Expansion of the
universe and the cosmic
red shift
2) Large amounts of
hydrogen, helium, and
other light elements
3) Age of the oldest known
objects is 13.7 billion
years old
4) Existence and properties
of the cosmic
background radiation or
(EMR)
Edwin Hubble (1889-1953)
Hubble is a famous astronomer who
proved that there were more galaxies
in space than just our own Milky
Way.
He worked with the Doppler Effect.
What is the Doppler Effect?
It is how the wavelengths of EMR are
squished or stretched because the
object and the observer are in motion.
In looking at the light and other EMR from
other galaxies, he noticed that the
spectra always appeared more red.
What does that tell us?
That the other galaxies are moving away
from us.
We call this the Red Shift.
1. The Red-Shift
• Red shift – As waves travel away from the
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observer, the wave seem to stretch. This is also
called lengthening.
lengthening
The light emitted by celestial bodies shift depending
upon whether the bodies are moving toward Earth
or away from it.
A change in the wavelength and frequency of light
is perceived as a change in color.
Animation of Big Bang
Animation of changes to the Spectra due to Red
Shift
2. Large Amounts of Hydrogen &
Helium
• No matter where we travel in
the universe, Hydrogen and
Helium are present
• We believe that the protons,
neutrons, and electrons that
are needed to make Hydrogen
& Helium were created when
the Big Bang occurred.
•Hydrogen & Helium formed
when the protons, neutrons,
& electrons collided into each
other with the hot temperatures
after the explosion
3. Age of the Oldest Known
Objects
• Using the brightness,
mass, color, and
chemical composition
we can estimate the
age of stars
• None have been
observed to be older
than about 13 billion
years
4. Cosmic Background Radiation
(EMR)
• All stars give off the same
types of EMR radiation.
• How could everything give
off the same types of
radiation?
• Only if the original universe
had EMR and when it
exploded, the EMR
traveled with all of the
pieces
A Brief
Look At
Time