the big bang: fact or fiction?
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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. - PowerPoint PPT PresentationTRANSCRIPT
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The Big Bang: Fact or Fiction?
The Big Bang
Fact or fiction?
Dr Cormac O’Raifeartaigh
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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
Expanding and cooling ever since
t~ 14 billion yr
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• gravity caused by sun’s mass
Newton
• planet orbits due to gravity
Newton’s gravity
2r
MmGF
What is pushing out?
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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
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Relativity and the expanding U
dynamic U
expand or contract
depends on mass
Apply Einstein’s gravity to Universe
Alexander Friedmann
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Evidence II: Composition of the elements
U = 75% H, 25% He
ObservedGeorges Gamow
BB Prediction
Heavier elements: 0.1%
Formed in stars
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Evidence III:Cosmic background radiation
BB prediction
radiation leftover from BB
low temperature
low frequency
Alpher, Gamow and Herman
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Cosmic microwave background (1965)
radio interference
low frequency
temperature 3 K
Penzias and Wilson
Echo of Big Bang
Observed
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Modern measurements
• accurate CMB spectrum
• homogeneous?
• how do galaxies form?
COBE satellite (1992)
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WMAP satellite
WMAP satellite (2002)
• highly homogeneous• flat universe • ev idence for inflation
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Inflation
explains galaxy formation
explains flatness of U
solves horizon problem
Hyper- expansion
immediately after BB
Alan Guth
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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
Known matter: 4%
Dark matter: 23%
Dark energy: 73%
Flat universe
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Evidence for general relativity
• bending of light by gravity
• time stretching by gravity
• black holes