1. The Big Bang: Fact or Fiction? The Big Bang Fact or fiction? Dr Cormac O’Raifeartaigh

2. The expanding universe (1929 ) many galaxies moving apart

3. The origin of the universe rewind graph: universe converges infinite density, temp beginning of time: Big Bang? Georges Lemaitre Expanding and cooling ever since t~ 14 billion yr

4. gravity caused by sun’s mass Newton planet orbits due to gravity Newton’s gravity What is pushing out?

5. Modern theory of gravity gravity = curvature of space-time space + time = space-time space-time not fixed affected by mass General theory of relativity Einstein

6. Relativity and the expanding U dynamic U expand or contract depends on mass Apply Einstein’s gravity to Universe Alexander Friedmann

7. Evidence II: Composition of the elements U = 75% H, 25% He Observed Georges Gamow BB Prediction Heavier elements: 0.1% Formed in stars

8. Evidence III: Cosmic background radiation BB prediction radiation leftover from BB low temperature low frequency Alpher, Gamow and Herman

9. Cosmic microwave background (1965) radio interference low frequency temperature 3 K Penzias and Wilson Echo of Big Bang Observed

10. Modern measurements accurate CMB spectrum homogeneous? how do galaxies form? COBE satellite (1992)

11. WMAP satellite WMAP satellite (2002) highly homogeneous flat universe ev idence for inflation

12. Inflation explains galaxy formation explains flatness of U solves horizon problem Hyper- expansion immediately after BB Alan Guth

13. New surprises U speeding up Supernova U flat Dark energy

14. Outstanding puzzles Nature of inflation? Nature of dark energy ? Singularity at time zero? Further reading: ANTIMATTER

15. Summary

16. The Big Bang model 14 billion years ago, universe concentrated at a point Primordial explosion of matter, energy, space and time Universe expanding and cooling ever since Misnomer: singularity problem

17. Cosmological model Known matter: 4% Dark matter: 23% Dark energy: 73% Flat universe

18. Evidence for general relativity bending of light by gravity time stretching by gravity black holes