Formation of the Universe

1. Formation of the Universe Pgs. 114 - 117

2. How did the universe begin? It is puzzling to try to figure out how everything in the entire universe came to be. The study of the origin and future of the universe is cosmology. Like other scientific theories, theories on the origin of the universe must be tested.

3. The Big Bang Theory The Big Bang Theory states that the universe began with a tremendous explosion. 10 – 15 billion years ago, all the contents of the universe were gathered together to under extreme pressure and temperature and density. Then it rapidly expanded eventually turning into galaxies.

5. A Big Crunch? As galaxies move apart, they get older and stop forming stars. If there is enough matter, gravity will slow and stop the expansion of the universe. It may even reverse direction and start to crunch together. If there is not enough matter, the stars age and die and the universe will eventually turn cold and dark.

6. Supporting the Theory Proof of the big bang comes from 1964 with two scientists using an antenna. They found radiation coming from all directions in space indicating that there is cosmic background radiation left over from the big bang. The theory states that thermal energy from the explosion was distributed in every direction as the universe expanded.

8. Universal Expansion The Big Bang Theory is widely accepted by astronomers. It came from the idea that the universe is expanding. We have found that galaxies are moving away from each other. If we look at that action in reverse, the universe would be contracting until it was all together at a single point.

9. A Raisin-Bread Model Imagine a loaf of raisin bread before it is baked. The dough has raisins set at a certain distance from other raisins. As it bakes the dough rises and the raisins get further and further from each other. The universe is like the raisin bread. It is expanding in all directions and the galaxies (raisins) are moving away from each other.

10. How old is the Universe? Scientists can measure the age of the universe by measuring the distance to the furthest galaxies. Since light travels at a constant speed, it can be used to determine the age of the galaxy. Also, we can use old, nearby stars. They must be as old as the universe or at least be created around the same time.

11. Structure of the Universe The universe stretches out farther than we can see with some of our most accurate instruments. All of the objects within the universe seem scattered randomly. Actually, they have a structure that is repeated over and over again.

12. A Cosmic Repetition Earth is one of the planets going around the sun. Other stars have been found to have planets orbiting them. Planetary systems might be more common than previously thought. Stars are grouped together in larger systems. Galaxies are even grouped together in clusters.

13. Multiple Universes Is the universe alone? Some cosmologists think that our universe is only one of many others. Currently, we do not know of any other universes. However, since we cannot see that far, other universes might be out there.