Post on 30-Aug-2018
Origin of the Universe
Universe = the totality of all the things that exist
There are 2 main theories for the origin
of the universe:
1. Big Bang Theory- the universe
began as a point and has been
expanding ever since.
2. Steady-state Theory- the universe
has always existed and does not
change with time.
When you look out into space, you are looking back in time.
The farther out you look the farther back in time you see.
Some of the stars you see may no longer exist!
The light from these stars left them long ago and is only now
reaching Earth.
Light that you see from the sun left the surface of
the sun about 8 minutes ago!
Big Bang Theory
Big Bang Theory Timeline
Time Event
0 - 0.01 Universe grew from size of a pin head to
second 2000 times size of the sun
Temperature = billions of degrees
1 second First elementary particles form (electrons, protons,
neutrons)
3 - 4 First atoms form (Hydrogen and Helium)
seconds Temperature = 900 million degrees
300,000 Matter condensed into clumps and formed
years first galaxies
Temperature = 4,000 degrees
1 billion years First stars formed
~10 billion Milky Way Galaxy formed
years
Milky Way Galaxy
Evidence to support the Big Bang:
1. Light coming from distant galaxies
indicates that the universe is expanding uniformly-
all points are moving away from all other points.
Uniform Expansion
2. Cosmic background radiation was detected in
1965 by a radio antenna at Bell Labs, Holmdel, NJ.
The background “noise” comes from all directions
and can be explained to be the result of
leftover radiation from an early, very hot universe.
Evidence to support the Big Bang:
Cosmic Background Radiation Discovered
Cosmic Background Radiation
Age of the universe:
The age of the universe can be found if you
know the rate of expansion of the universe
(H = Hubble constant).
• If the expansion rate is relatively slow, the
universe is relatively ___?___
• If the expansion rate is relatively fast,
the universe is relatively ___?___
The universe is thought to be 13 to 15 billion
years old.
What is the universe made of?
Lithium Atom
Astronomers think the universe is made up of only
three things:
1. Atoms (4%)- “normal matter.”
The stars and planets account for only 0.4%
of the universe.
Eagle Nebula
Intergalactic gas, or nebula, makes up 3.6%
Orion Nebula
Black Hole
2. Dark Matter (22%)- matter that does not give off
light but has gravity. Black holes are a type of dark
matter. They are so dense and massive that their
gravity pulls everything in, including light.
Nothing escapes!
Milky Way Galaxy
3. Dark Energy (74%)- a force that opposes gravity.
Scientists know almost nothing about dark energy.
It appears to be pushing galaxies apart, causing the
rate of expansion of the universe to accelerate-
speed up!