1. Evidence for an Expanding Universe with a Finite Beginning

2. Hubble’s Observations
First to show that Universe was expanding
How??

3. Hubble’s Observations
Using a standard candle (star of known brightness), Hubble showed that stars are moving away from each other based on their relative brightness
Also showed that more distant stars are moving away more quickly than close stars

4. Cosmic Background Microwave Ratiation
Discovered by accident in 1965, background microwave radiation can be detected at uniform (equal) levels throughout the visible universe
Importance?

5. CMBR Continued
Big Bang models predicted residual heat throughout the universe
Microwaves show residual heat in the very low end of the spectrum
Even distribution of heat showed a common source of heat from long ago

6. Even Distribution of Matter
Like the confetti in our class, matter is evenly distributed throughout the universe
H, He, and Li are found at expected levels based upon initial events of Big Bang

7. Color Shift

8. Color Shift
Approaching stars appear more blue than expected, due to their shorter wavelenths
Receding stars appear more red than expected, due to their longer wavelengths
Vast majority of stars in the visible universe are more red than expected - evidence of a still-expanding universe