1. Big Bang Theory

2. What is a Theory?
Well-established idea that is supported by scientific evidence.
Theory statements can be refuted, but not verified, no matter how strongly we believe in the truth of a theory. It is always possible for it to be falsified.

3. How do we measure distances in space?
Astronomical Unit (AU) – average distance between the Earth and the Sun
About 93 million miles
Light-year – the distance that light travels in a year
Used to measure distance to stars and galaxies
Nearest stars are several light-years away

4. What is the size scale in space?
Put the following in order from smallest to largest:
Galaxy
Universe
Planet
Star
Comet
Solar system
Asteroid

5. What is the size scale in space?
Put the following in order from smallest to largest:
Comet
Asteroid
Planet
Star
Solar system
Galaxy
Universe

6. What is Hubble’s Law?
Hubble then noticed a correlation between the distance of the galaxies and the speed at which they are moving away from us
The farther away the galaxy,
the faster it is receding
(moving away) from the Earth.

8. So if the universe is expanding, then it must have had a beginning.

9. What is the Big Bang Theory?
Universe formed 12 to 14 billion years ago
At “time zero” universe was an explosion of a primeval atom.
Temperatures extremely high at beginning
Expanded rapidly, temperatures dropped
Matter formed from original energy

10. What evidence is there for the Big Bang Theory?
Cosmic background radiation: radiation left over from the initial moments of Big Bang spread evenly around the universe.
Red Shifted galaxies indicating that they are moving away from our galaxy.
Galaxies and stars formed from cooling energy.
Leftover heat from the original explosion

12. Big Bang model describes our current understanding of the universe.
New discoveries, such as dark matter and accelerating expansion (Dark Energy), lead us to refine our model, but there is no crisis in our understanding (yet).
Science is an ongoing process - forcing us to test our model through prediction and observation. The more tests it passes, the greater is our confidence in it.