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The Big Bang Theory (Part II)
The Evidence that Supports It
Mike StuckeyWarren East High School
Evidence of the Big Bang
No human was present at the beginning of the
universe, so how do we know this is what happened
?
What evidence is there ?
Evidence of the Big Bang
We can’t test our ideas by creating little universes (although this would be
really cool.)
What evidence is there ?
Evidence of the Big Bang
To answer this question we must first recall how
science is done.Scientists first create a model
based on observations.
Then scientists make predictions based on these models.
Scientists then try and verify these predictions experimentally or
observationally.
Evidence of the Big Bang
Prediction
The most abundant element in the universe should be Hydrogen.
Observation
Although we clearly can’t test the entire universe, all celestial
objects we can see tell us that the most abundant element in each is
hydrogen.
Evidence of the Big Bang
Prediction
The concentration of Helium should be greater than 25%.
ObservationDirectly observing evidence of helium is difficult, but when we can measure its
concentration in stars we find that it ranges from 27 to 30 % Helium.
Evidence of the Big Bang
Prediction
The universe should be expanding
Edwin Hubble Vesto M. Slipher
Observation
In 1928, Edwin Hubble and Vesto M. Slipher, confirmed separately that the universe is expanding. They
used the Doppler Red Shift of stars and galaxies to prove this.
Doppler Effect for Light
When a light source moves away from you, the light it emits shifts toward the red spectrum. This is called Red
Shift.
When a light source moves away from you, the light it emits shifts toward the red spectrum. This is called Red Shift.
When a light source moves away from
you, the light it emits shifts toward the red spectrum. This is called Red
Shift.
When a light source moves away from you, the light it emits shifts
toward the red spectrum. This is called Red
Shift.
When a light source moves away from you, the light it emits
shifts toward the red spectrum. This is called Red Shift.
RED SHIFT
RED SHIFT
The galaxies that we observe exhibit the red shift showing that they are moving away from
us.
This observation shows that the universe is expanding!
This evidence supports the Big Bang Theory!
Doppler Effect for Light
Evidence of the Big Bang
Prediction
When the universe began, the four fundamental forces were actually one
force.
The Fundamental Forces
Gravitational Force
Electromagnetic Force
Nuclear Strong Force
Weak Force
Evidence of the Big Bang
Prediction
When the universe began, the four fundamental forces were actually one
force.
Observation
This hasn’t been completely proven, but there is an incredible amount of symmetry between the forces, look at Coulomb’s Law and Newton’s Law of
Gravitation.
In 1983, at Cern Labs, particles were slammed together in their accelerator at extremely high
temperatures and the Electromagnetic Force and the Weak Force were shown to be one force called the Electroweak force.
Evidence of the Big BangDirect Observation of the Visible
Universe
It takes a finite amount of time for light to travel a distance. In one second light travel
about 300,000,000 meters.
The distance light travels in a year is called a light-year (ly).
When we look at distant stars or galaxies, we actually are seeing how they looked at some time
in the past.
Direct Observation of the Visible Universe
• It takes light from the Sun approximately 8.3 minutes to reach the Earth
• This means that if we are looking at the Sun we see how it was 8.3 minutes ago. We are looking into the past.
Direct Observation of the Visible Universe
• Alpha Centauri is 4.3 ly away.
• This means it takes light from this star 4.3 years to reach us.
• We are looking 4.3 years into the past.
Direct Observation of the Visible Universe
• Betelgeuse is 1400 ly away.
• This means it takes light from this star 1400 years to reach us.
• We are looking 1400 years into the past.
Direct Observation of the Visible Universe
• The galactic center is 20,000 to 30,000 ly away.
• This means it takes light from the galactic center 20,000 to 30,000 years to reach us.
• We are looking 20,000 to 30,000 years into the past.
Direct Observation of the Visible Universe
• The Andromeda galaxy is 2 million ly away.
• This means it takes light from this galaxy 2 million years to reach us.
• We are looking 2 million years into the past.
Direct Observation of the Visible Universe
• The Hydra Cluster is 3.6 billion ly away.
• This means it takes light from this cluster of galaxies 3.6 billion years to reach us.
• We are looking 3.6 billion years into the past.
Direct Observation of the Visible Universe
• This galaxy is 13.2 billion ly away.
• This means it takes light from this galaxy 13.2 billion years to reach us.
• We are looking 13.2 billion years into the past. Not real long after the Big Bang
Evidence of the Big Bang
Background Radiation
A crucial moment in the creation of the universe was when the atoms that were
present became neutral and the radiation was able to flow through it and expand
with the universe.
This allowed matter to begin clumping to form the structures we observe in the
universe.
Evidence of the Big Bang
Prediction
The temperature of the background radiation should be 2.7 K
Robert Wilson
Arno Penzias
Observation
In 1964, Robert Wilson & Arno Penzias, detected this background
radiation and determined its temperature to be 3.5 K. For this they received the Nobel Prize in Physics. Further experiments have
found that temperature to be 2.7 K.
Map of the Background Radiation
In 2003 the WMAP satellite mapped
the cosmic background
radiation, further confirming its
temperature to be 2.7 K.
This map also gave us great
detail about the early universe and it allowed us to refine the
age of the universe to 13.7 billion years.
Map of the Background Radiation
This picture shows us how the universe looked 379,000 years
after the Big Bang.
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