1. THE UNIVERSE
Part 2:Cosmology

2. Cosmology
The universe is the name given to everything that exists. This includes moons, planets, stars, galaxies. There is an awful lot of “stuff” that makes up the universe. Where did it all come from and where is it all going? The short answer is that no one really knows for sure!

3. Cosmology
The Steady State Theory (1948)
The Steady State Theory suggested that the universe, although
expanding, had no origin and it has always existed. As the
universe expands, an incredibly large amount of matter is
created every second, to keep the universe looking exactly the
same all of the time.
The universe has always looked as it looks now and will forever
appear the same. The density of matter is constant over time.

4. Cosmology
The Big Bang Theory (1927)
The Big Bang Theory is currently the most widely accepted theory of the origin of the universe. The fact that the Steady State theory was based on the continuous creation of matter made some scientists doubtful.

5. Cosmology
The theory suggests that a long time ago (about 14 billion years ago) the universe started as a big explosion. All the energy and matter which exists today came from this original explosion. Time started from this event

6. Steady State vs. the Big Bang Theory
Cosmology
Steady State vs. the Big Bang Theory

7. Cosmology The evidence for this theory comes from two observations.
Evidence for the Big Bang Theory
The evidence for this theory comes from two observations.
1. Light from stars in other galaxies is red shifted.
2. There is cosmic microwave background radiation (CMBR) everywhere in space.

8. Cosmology
Scientists did some mathematical calculations on what would have happened in the Big Bang. Their calculations showed that there should be a low level of microwave radiation as a result of the original explosion. When they looked out into space, they found this background microwave radiation everywhere. The Big Bang Theory is the only theory which explains the CMBR.

9. Cosmology
The Doppler Effect
In the same way that sound waves are compressed (or squashed) by an object coming towards you, light waves from stars coming towards us are also compressed. In other words a star coming towards us has its light wavelengths squashed. This is referred to as a blue shift.
The Doppler effect car picture

10. Cosmology
On the other hand, a star moving away from us has its light wavelengths get longer. This is referred to as red shift. So if the universe is constantly expanding, which colour do you think would be detected?

11. Cosmology
When light wavelengths get longer, they shift towards the red end of the spectrum. This shows itself in an effect called the red shift discovered by Christian Doppler in
Example of a Red Shift
Normal Spectrum
Shifted Spectrum
Violet Indigo Blue Green Yellow Orange Red

12. Cosmology
Astronomers can tell whether stars and galaxies are moving away from the Earth or towards the Earth depending on their red shift or blue shift. This phenomenon has led to the ability to calculate the distance of stars and galaxies from the Earth. Edwin Hubble was an American astronomer who studied light from other galaxies using the most powerful telescope in the world in the 1920s, at the Mount Wilson Observatory in California. He spread the light into a spectrum and found that in almost all cases, the light was red shifted.

13. Cosmology
Hubble realised that we live in a universe that is expanding outwards in all directions. He also discovered that the further a galaxy is from Earth, the faster it is moving away from us. This is known as Hubble’s Law.

14. Cosmology
Large Hadron Collider

15. Cosmology
The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator. Scientists are trying to answer questions like:
What is the Universe made of?
How did it start?

16. Cosmology
Scientists recreate the conditions of the big bang, speeding up subatomic particles to the speed of light, assessing how the particles collide and the debris following these collisions.

17. Cosmology Controversy
Before the LHC was started up, many people believed that the collision of sub-atomic particles may generate microscopic Black Holes, which would expand and ultimately consume our planet.
These theories were analysed
by scientists and ultimately
proven wrong upon start up
of the LHC