E6.1-6.3

E.6.1 Describe the distribution of galaxies in the universe

Galaxies tend to be found clustered together.
Galactic Cluster - a collection of galaxies that is drawn together by their mutual gravitational attraction. the clusters themselves are involved in larger groups called superclusters. For example, our own galaxy, the larger spiral galaxy Andromeda  and several smaller satellites, including the Large and Small Magellenic Clouds.

Galactic supercluster - they are typically seen as long and thin strands of clusters and galaxies, intra-cluster gases and, presumably, "dark matter" on a two dimensional surface.

http://www.dragonslain.com/Science_scene_Galaxies.html

E.6.2 Explain the red shift of light from distant galaxies

- A red shift implies that the star is receding, thus the light from the galaxy must also be receding since they are red shifted as well.
- It was found that light from all galaxies are red shifted and most importantly, the furthest ones are shifted more than the closer ones. Thus implying that the universe is EXPANDING!
- It is as if the a big explosion had occurred, causing the outer parts to fly off faster and is still travelling outwards with the greatest speed. - Heinemenn HL Physics Textbook Chris Hamper

Watch and embed these video: http://www.youtube.com/watch?v=BIW7EzHmndY&feature=related

Notes:

• our universe is continually expanding
• we know this because when we look at galaxies, they are all moving away from us
• the closer galaxies are moving at a slower rate then the ones that are further away
• the relationship between the distance of the galaxy and how fast it appears to be moving away from us is known as HUBBLE's LAW
• as the universe expands, it 'drags' the galaxies along with it
• the overall motion away from us is due to th expansion of the universe
• as our universe expands, the galaxies with it do not
• on small scale, gravity can hold things together. on large scale the expansion takes over causing everything to move apart
• astronomers now know that dark energy is causing our universe to expand at an accelerating rate
• however, we are NOT at the center of the universe. If we are to look at the galaxies of the universe from different galaxies, you would see the same thing
• The centre of the universe is nowhere or everywhere is the centre of the univers

http://www.youtube.com/watch?v=e6G2Z6iD-9M&feature=related

Why the galaxies furthest away are red shifted the most:

Because the universe is EXPANDING. It was found that light from all galaxies are red shifted and most importantly, the furthest ones are shifted more than the closer ones. 

Explain why it is the expansion of space itself rather than the motion of the galaxy that results in the relative velocities of the galaxies

Since the universe is expanding, it is causing the majority of the galaxies to move further away from us. it is the expansion of the universe that results in the galaxies relative velocities. We know that it is the expansion itself and not the motion of the galaxy because we can observe the galaxy that is visible to us that it is moving away from us. 

E.6.3 Questions: