- Current evidence suggests that the universe is expanding and that space expanded violently and rapidly from a very small initial 'point'
- The Big Bang Theory: states that originally all the matter in the universe was concentrated into a single incredibly tiny point
- This began to expand rapidly in a hot explosion and is still expanding today
- The Big Bang happened about 13.7 million years ago
- Doppler effect
- Sirens: high-pitched when they come towards then low-pitched as it goes away
- When an object moves away from its observer, its light is affected by the Doppler effect
- The Sun contains helium, we know this because there are black lines in the spectrum…