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The Big Bang: Fact or Fiction?

The Big Bang: Fact or Fiction?. The Big Bang. Fact or fiction?. Dr Cormac O’Raifeartaigh. The expanding universe (1929 ). many galaxies moving apart. rewind graph: universe converges infinite density, temp beginning of time: Big Bang?. The origin of the universe. Georges Lemaitre.

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The Big Bang: Fact or Fiction?

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

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

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

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

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

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

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

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

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

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

  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

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