1. The Science of Creation
The Big Bang Evidence
The Science of Creation

2. Goals What is the evidence for the Big Bang?
What predictions does the Big Bang theory make?
What observations can we make?
How good of a theory is the Big Bang?

3. Scientific Evidence A scientific model must do two things:
Explain what is seen.
Predict what will happen accurately.
Or, predict what can be seen before one thinks to look.

4. Cosmic Microwave Background
The Big Bang:
Massive amount of energy.
Very high temperature  thermal radiation
As Universe expands:
Temperature cools  thermal radiation gets redder. or
Cosmological redshift  same thing.

5. Origin of the CMB
Once cool enough for atoms, radiation could move freely through space.

6. The Temperature of Space
After 500,000 yrs: T=3000K
lpeak a 1/T
lpeak = near infrared.
The Universe was red.
After 16 billion yrs:
Universe 1000x bigger.
lpeak = 1000x longer.
lpeak = microwaves (radio).
T = 3K!

7. Where do you look? Recall Lookback time. Universe is a time machine.
Look beyond the youngest galaxies.
Look everywhere.

8. What We See

9. Cosmic Microwaves
Big Bang theory predicted cosmic microwave background.
In 1965: discovery of radio waves (microwaves) from sky.
Prediction confirmed.

10. COBE Early 1990s: NASA Cosmic Background Explorer
Measure the intensity of radiation at many wavelengths.
3K thermal emission!
lpeak = (3 x 10-3 m/K) / 3 K = 0.001m = 1mm

11. COBE cont.
Also measure the (temperature) intensity and wavelength in various directions.
Look for fluctuations out of which galaxies came.
V = 600 km/s

13. Olbers’ Paradox Why is it dark at night?
In an infinite and unchanging universe:
Every line of sight should end at the surface of a star.

14. A Good Theory? The Big Bang is a very successful theory.
Makes predictions:
CMB.
Hydrogen, Helium, Lithium abundances.
Formation of structure.
Expansion of Universe.
Are other Creation theories:
Scientific?
Successful?