The universe: dark matter and dark energy

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The universe dark matter and dark energy
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Cosmic Microwave Background was discovered in 1965

• This really is a map of the sky, black zero
  emission, green that of a blackbody of 2.7K!

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To see ripples in the CMB, you really have to go
down in sensitivity

• Results from spacecraft WMAP, released on
  February 11, 2003

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From these tiny fluctuations grew the structure
we see in the universe today
Clusters of galaxies, galaxies, and stars
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So what kind of universe do we live in? open,
closed?

• Recall that it depends on the mean density
• Via the parameter

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Determining the mean density of the universe
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The answer is.

• For bright matter omega 2.2E-03
• All baryonic matter (from abundance of light
  elements), omega 0.02 0.05
• Taking account of dark matter in clusters of
  galaxies, omega 0.33
• Best estimate is that omega lt 1
• Abstract of Turner article

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The truly weird feature of this is that most of
the matter in the universe is not even Baryonic,
and thus is of an unknown form. Taken at face
value, this result indicates that omega is lt 1,
and we live in an open universe. This was the
status a few years ago. Then things got even
stranger
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• For Omega 1, the fan out is the smallest
• For Omega 0.33, it is larger
• For Omega 0, it is larger still, and the
  maximum for a Friedmann universe

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Use cosmological model to calculate m of z
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What is found for Type Ia SN
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The Expansion of the Universe is Accelerating

• Not explicable in terms of a Friedmann universe
• Behavior requires addition of Cosmological
  Constant to the theory
• Physically, corresponds to Dark Energy, an
  energy field the produces long range, repulsive
  force
• Dark energy can contribute to Omega, make it 1

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Contemporary Precision Cosmology

• Omega of Baryonic matter 0.02 0.05
• Omega of all matter 0.33
• Omega of Dark Energy 0.67
• Age of Universe 13.7 Gyr
• Inflation occurred 1E-34 sec after Big Bang,
  during which universe puffed up by factor of 1E25

Total 1
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In spite of precision, still some (very)
unsatisfactory aspects

• Nature of the Dark Matter unknown. When (if ever)
  will we confirm its existence in a laboratory?
• Nature of the Dark Energy is completely unknown

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Implications for our view of ourselves
The Realization that the majority of the matter
in the universe might be non-Baryonic is the
ultimate Copernican viewpoint not only are we in
no special place in the universe, but we arent
even made out of the same stuff as dominates the
matter density of the universe. Andrew Liddle
An Introduction to Modern Cosmology
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The Truth is out there