The Big Bang: Fact or Fiction

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The Big Bang Fact or Fiction?
The Big Bang
Fact or fiction?
Dr Cormac ORaifeartaigh
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The expanding universe (1929)
many galaxies moving apart
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The origin of the universe

• rewind graph universe converges
• infinite density, temp
• beginning of time Big Bang?

Georges Lemaitre
t 14 billion yr
Expanding and cooling ever since
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Newton
Newtons gravity

• planet orbits due to gravity

• gravity caused by suns mass

What is pushing out?
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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
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Relativity and the expanding U
Apply Einsteins gravity to Universe
Alexander Friedmann

• dynamic U
• expand or contract
• depends on mass

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Evidence II Composition of the elements
BB Prediction

• U 75 H, 25 He
• Observed

Georges Gamow
Heavier elements 0.1 Formed in stars
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Evidence IIICosmic background radiation

• BB prediction
• radiation leftover from BB
• low temperature
• low frequency

Alpher, Gamow and Herman
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Cosmic microwave background (1965)
Observed

• radio interference
• low frequency
• temperature 3 K

Penzias and Wilson
Echo of Big Bang
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Modern measurements

• accurate CMB spectrum
• homogeneous?
• how do galaxies form?

COBE satellite (1992)
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WMAP satellite

• highly homogeneous
• flat universe
• ev idence for inflation

WMAP satellite (2002)
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Inflation
Alan Guth
Hyper- expansion immediately after BB

• explains galaxy formation
• explains flatness of U
• solves horizon problem

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New surprises

• U speeding up
• Supernova
• U flat
• Dark energy

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Outstanding puzzles

• Nature of inflation?
• Nature of dark energy ?
• Singularity at time zero?

Further reading ANTIMATTER
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Summary
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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
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Cosmological model
Flat universe

• Known matter 4
• Dark matter 23
• Dark energy 73

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Evidence for general relativity

• bending of light by gravity
• time stretching by gravity
• black holes