The Big Bang Theory
How the Universe Formed.
Cosmology
The study of the nature and
evolution of the universe.
Not
and
Notthe
thestudy
studyofofcosmetics
Bill Cosby
beauty supplies.
Assumptions
Made
FG = G
M1M2
2
d
Assumption 1 :
The universality of physical laws
->
The laws of physics
are the same everywhere
and
MM
F =G 2
G
d
1
2
Assumptions
Made
Assumption 1 :
The universality of physical laws
Homogeneous
Universe
Assumption 2 :
The cosmos is homogeneous
->
Matter and radiation are
spread out uniformly w/ no
large gaps or bunches.
Non-Homogeneous
Universe
Assumptions
Made
Assumption 1 :
The universality of physical laws
US
Isotropic
Universe
Assumption 2 :
US
The cosmos is homogeneous
Assumption 3:
The universe is isotropic
->
same properties in all
directions
->
no center and no direction
Anisotropic
Universe
Assumptions Made
Assumption 1 :
The universality of physical laws
Assumption 2 :
The cosmos is homogeneous
Assumption 3:
The universe is isotropic
Now
Let’s Create
The Universe !!
Imagine
Imagine
NOTHING
Imagine
NOTHING
Nothing to see !
Imagine
NOTHING
Nothing to see !
Nothing to hear !
Imagine
NOTHING
Nothing to see !
Nothing to hear !
Nothing to feel !
Imagine
NOTHING
Nothing to see !
Nothing to hear !
Nothing to feel !
Nothing to think !
No Matter !
No Matter !
No Energy !
No Matter !
No Energy !
No Time !
No Pizza !!!!!!!!!
NOTHING
Then, about 13.7
billion years ago,
something happened
…..
An infinitely small point of energy is
formed.
It disrupts the “nothingness” and
begins to expand.
This is where and when the universe
began.
Energy and time are created, but no
matter !!!
Primeval Fireball
The universe is in an extremely high state of
energy, with temperatures estimated to be
greater than 1032 K.
It is just #$?! hot !!!!
But this ball of energy quickly expands and
cools.
Heavy Particle Era
The temperature is greater than 1012 K
Less than 0.000001 seconds after the Big Bang
At these temperatures photons collide to
produce massive particles and antiparticles, such
as protons and antiprotons.
Heavy Particle Era
The temperature is greater than 1012 K
Less than 0.000001 seconds after the Big Bang
These massive particles and antiparticles also
collide and annihilate each other producing
more photons.
Heavy Particle Era
The temperature is greater than 1012 K
Less than 0.000001 seconds after the Big Bang
At the end of this era, the universe is a thick
soup of heavy particles, antiparticles and energy.
The most important particles present are the
protons.
Light Particle Era
The temperature is greater than 6x109 K
Less than 6 seconds after the Big Bang
Because of the lower temperatures during this
era, the photons present can’t produce anymore
heavy particles. These photons can collide to
produce light particles and antiparticles, like
electrons and positrons.
Light Particle Era
The temperature is greater than 6x109 K
Less than 6 seconds after the Big Bang
During this era protons and electrons interact to
form neutrons. Antiprotons and positrons
interact in the same way.
Proton (+)
Neutron
Electron
(-)
Light Particle Era
The temperature is greater than 6x109 K
Less than 6 seconds after the Big Bang
Some of the neutrons decay back into protons
and electrons. The neutrons which survive are
very important for the next era.
Proton (+)
Neutron
Electron
(-)
Light Particle Era
The temperature is greater than 6x109 K
Less than 6 seconds after the Big Bang
At the end of this era the universe consists of
heavy and light particles (protons & electrons).
The universe also has neutrons.
Light Particle Era
The temperature is greater than 6x109 K
Less than 6 seconds after the Big Bang
At the end of this era the universe consists of
heavy and light particles (protons & electrons).
The universe also has neutrons.
The low temperatures don’t allow any more
matter/antimatter pairs to form from colliding
photons and no more neutrons can be formed.
Nucleosynthesis Era (Part I)
The temperature is around 109 K
Less than 300 seconds after the Big Bang
The neutrons which remain react with the
protons to form an isotope of Hydrogen called
Deuterium. (1 proton and 1 neutron)
Nucleosynthesis Era (Part I)
The temperature is around 109 K
Less than 300 seconds after the Big Bang
The neutrons which remain react with the
protons to form an isotope of Hydrogen called
Deuterium. (1 proton and 1 neutron)
All neutrons either become part of the
Deuterium or decay.
Nucleosynthesis Era (Part I)
The temperature is around 109 K
Less than 300 seconds after the Big Bang
Deuterium fuses to form Helium. At this point
the total mass of the Helium formed is about
25% the total mass of the universe.
Nucleosynthesis Era (Part I)
The temperature is around 109 K
Less than 300 seconds after the Big Bang
Deuterium fuses to form Helium. At this point
the total mass of the Helium formed is about
25% the total mass of the universe.
Some Tritium (Hydrogen with 2 neutrons),
Lithium and Berylium also form.
Nucleosynthesis Era (Part I)
The temperature is around 109 K
Less than 300 seconds after the Big Bang
In the first 5 minutes after the Big Bang, heavy
and light particles and antiparticles are formed.
Nucleosynthesis Era (Part I)
The temperature is around 109 K
Less than 300 seconds after the Big Bang
In the first 5 minutes after the Big Bang, heavy
and light particles and antiparticles are formed.
Neutrons are formed from protons and electrons,
these neutrons combine with the protons to form
the first stable nuclei of atoms. (Note: These
atoms still have not captured the electrons, too
much energy)
Nucleosynthesis Era
The temperature is around 3000 K
About 1 million years after the Big Bang
At these low temperatures the nuclei which have
formed can now capture electrons and become
neutral.
Nucleosynthesis Era (Part II)
The temperature is around 3000 K
About 1 million years after the Big Bang
At these low temperatures the nuclei which have
formed can now capture electrons and become
neutral.
This allows light and radiation to pass through
the neutral atoms and expand throughout the
universe cooling to around 2.7 K
Matter Era
The temperature is less than 3000 K
Over 1 million years after the Big Bang
With the radiation and matter freed from each
other, the pressures which kept the matter from
clumping together is now greatly reduced.
Matter Era
The temperature is less than 3000 K
Over 1 million years after the Big Bang
With the radiation and matter freed from each
other, the pressures which kept the matter from
clumping together is now greatly reduced.
Matter is able to clump together forming
galaxies, stars, and the Earth.
Matter Era
The temperature is less than 3000 K
Over 1 million years after the Big Bang
With the radiation and matter freed from each
other, the pressures which kept the matter from
clumping together is now greatly reduced.
Matter is able to clump together forming
galaxies, stars, and the Earth.
We are still in this era.
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.
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.
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.
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.
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%.
Evidence of the Big Bang
Prediction
The concentration of Helium should be greater than
25%.
Observation
Directly 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
Evidence of the Big Bang
Prediction
The universe should be expanding
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.
Evidence of the Big Bang
Prediction
When the universe began, the four fundamental forces
were actually one 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 (Electrical Force) and
Newton’s Law of Gravitation (Gravitational Force).
Evidence of the Big Bang
Prediction
When the universe began, the four fundamental forces
were actually one force.
Observation
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 Bang
Direct 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.
Evidence of the Big Bang
Direct 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).
Evidence of the Big Bang
Direct 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 objects, like stars and galaxies we are
actually looking into their 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
• 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 is 2.7 K
Robert
Wilson
Arno
Penzias
Evidence of the Big Bang
Prediction
The temperature of the background radiation is 2.7 K
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.
Now
Let’s Destroy
The Universe !!
The End of the Universe
There are three possible futures for our
universe.
Which one will be our fate depends on the
total mass of the universe or more
accurately, its density.
The End of the Universe
It was Albert Einstein who
calculated a critical density
for the universe.
The End of the Universe
It was Albert Einstein who
calculated a critical density
for the universe.
This value is about
5 x 10-27 kg/m3 .
The End of the Universe
It was Albert Einstein who
calculated a critical density
for the universe.
This value is about
5 x 10-27 kg/m3 .
The fate of the universe
depends on whether or not
the density is above or below
this value.
The End of the Universe
The density of the universe is less than the
critical value of 5 x 10-27 kg/m3
The gravitational pull of the universe will not be
enough to stop the expansion of the universe.
The End of the Universe
The density of the universe is less than the
critical value of 5 x 10-27 kg/m3
The gravitational pull of the universe will not be
enough to stop the expansion of the universe.
The universe will expand forever.
The End of the Universe
The density of the universe is less than the
critical value of 5 x 10-27 kg/m3
The gravitational pull of the universe will not be
enough to stop the expansion of the universe.
The universe will expand forever.
The overall temperature of the universe will decrease
The End of the Universe
The density of the universe is less than the
critical value of 5 x 10-27 kg/m3
The stars will all eventually burn out and no new stars
will form.
The End of the Universe
The density of the universe is less than the
critical value of 5 x 10-27 kg/m3
The stars will all eventually burn out and no new stars
will form.
Protons will eventually begin to decay. This is when
the matter era will end and the universe will become
just a soup of quarks and other subatomic particles.
The End of the Universe
The density of the universe is equal to the
critical value of 5 x 10-27 kg/m3
The gravitational pull of the universe will ultimately
stop the expansion of the universe.
The End of the Universe
The density of the universe is equal to the
critical value of 5 x 10-27 kg/m3
The gravitational pull of the universe will ultimately
stop the expansion of the universe.
An equilibrium will be reached and the universe will
last forever in this state (it may or may not be the
matter era).
The End of the Universe
The density of the universe is greater than the
critical value of 5 x 10-27 kg/m3
The gravitational pull of the universe will ultimately
stop the expansion and cause the universe to collapse.
The End of the Universe
The density of the universe is greater than the
critical value of 5 x 10-27 kg/m3
The gravitational pull of the universe will ultimately
stop the expansion and cause the universe to collapse.
The universe will return to one point and time.
The End of the Universe
The density of the universe is greater than the
critical value of 5 x 10-27 kg/m3
The gravitational pull of the universe will ultimately
stop the expansion and cause the universe to collapse.
The universe will return to one point and time.
Will the universe begin again ????
The End of the Universe
The density of the universe is greater than the
critical value of 5 x 10-27 kg/m3
The gravitational pull of the universe will ultimately
stop the expansion and cause the universe to collapse.
The universe will return to one point and time.
Will the universe begin again ????
The End of the Universe
Currently scientists have determined the density
of the universe to be less than 5 x 10-27 kg/m3.
The End of the Universe
Currently scientists have determined the density
of the universe to be less than 5 x 10-27 kg/m3.
If this is true the universe will expand forever.
The End of the Universe
Currently scientists have determined the density
of the universe to be less than 5 x 10-27 kg/m3.
If this is true the universe will expand forever.
BRRRRRRRRR !!!!!!!!
The End of the Universe
Currently scientists have determined the density
of the universe to be less than 5 x 10-27 kg/m3.
If this is true the universe will expand forever.
BRRRRRRRRR !!!!!!!!
However the discovery of dark matter could
change the ultimate fate of the universe.