What is the Origin of the Universe?

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What is the Origin of the Universe?
What is the Fate of the Universe?
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How Old is the Universe?

• 1644 Dr. John Lightfoot, Vice Chancellor of
  Cambridge University, uses biblical genealogies
  to place the date of creation at September 21,
  3298 BC at 9 AM (GMT?)
• 1650 James Ussher, Archbishop of Armagh and
  Primate of All Ireland, correlates Holy Writ and
  Middle Eastern histories to correct the date to
  October 23, 4004 BC
• Current Jewish calendar would suggest a date of
  creation about Sep/Oct 3760 BCE

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Cosmological Principle

• At any instant of time, the universe must look
  homogeneous and isotropic to any observer.

Perfect Cosmological Principle
.and indistinguishable from the way it looked
at any other instant of time.
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How Old is the Universe?

• 1760 Buffon uses cooling of Earth from its
  molten state to estimate age as 7.5x104 years
• 1831 Charles Lyell uses fossils of marine
  mollusks to estimate age as 2.4x108 years
• 1905 Lord Rutherford uses radioactive decay of
  rocks to estimate age as gt 109 years (later
  refined to 4.3x109 years)

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Equivalence Principle
Consider a test particle with mass m and charge q
Electrostatic force on q due to Q _at_ r is Fe q
(kQ/r2)
? acceleration Fe/m q/m (kQ/r2)
Gravitational force on m due to M _at_ r is Fg m
(GM/r2)
? acceleration Fg/m m/m (GM/r2) GM/r2
if gravitational and inertial masses are
equivalent
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• but the equilibrium is unstable. In order to
  prevent the universe from either expanding or
  contracting, Einstein introduced a scalar field
  that was called
• The Cosmological Constant
• in order to keep the universe static.

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Astronomical Redshifts

• ? observed wavelength
• ?o laboratory or rest wavelength
• ?? ? ?o
• (1 z) ?
• z redshift v(cv)/(c-v) - 1 ?vltltc v/c

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The Age of the Universe
No gravity v Hor ? to r/v Ho-1
Newtonian gravity for a flat universe
½ mv2 - GmM/r 0 ? v dr/dt (2GM/r)½
so we can integrate r½dr (2GM)½dt to get
to 2/3 (r3/2GM)½ 2/3 (r/v) 2/3 Ho-1
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from An Essay on Criticism by Alexander
Pope
A little Learning is a dang'rous Thing
Drink deep, or taste not the Pierian
SpringThere shallow Draughts intoxicate the
Brain,And drinking largely sobers us again.
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Cosmological Principle

• At any instant of time, the universe must look
  homogeneous and isotropic to any observer.

Perfect Cosmological Principle
.and indistinguishable from the way it looked
at any other instant of time.
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Steady-State Theory
The expansion of the universe is balanced by the
spontaneous production of bubbles of
matter-anti-matter, so that the Perfect
Cosmological Principle is preserved.
Nucleosynthesis in stars can account for the
abundances of all the elements except the very
lightest is that a problem?
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Gamows Test for a Big Bang versus a Steady
State Universe

• If there was a Big Bang, there should be some
  cooling remnant radiation (now maybe 5K?) that
  pervades the universe
• If, instead, the universe is always the same,
  there should NOT be any cooling radiation

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Evidence for the Hot Big Bang
Hubble flow
Ho measures the universe at approximately t
1010 yrs
Cosmic microwave background radiation
CMB measure the universe at approximately t 4
x105 yrs
Abundances of the light elements
BBN measures the universe at approximately t
200 s
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The Matter/Anti-matter Problem
Why doesnt there appear to be as much
antimatter as ordinary matter in the universe?
(or at least there was!)
There is!
In the early universe, the imbalance was
less than one part in 1010, so that when all the
stuff in the dense early universe annihilated
it left a small residual of matter and all those
photons!
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So Whats the Problem(s)?
The horizon problem
How did the universe become so homogeneous on
large scales?
The flatness problem
Why is density of the universe so close to the
critical density?
The structure problem
Is there a physical origin for the density
perturbations?
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Critical Energy Density of the Universe
Total energy associated with a galaxy of mass m
½ mv2 - GmM/r
? 0 if barely bound
M 4/3 pr3?now 4/3 pr3?o
r (t) a(t) H-1(t)v(t)
? r Ho-1v
?o ¾ M/(pr3) 3/8 v2/(pGr2) 3Ho2 /(8pG)
O ?/?o ? 1 if the universe is flat
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The current value of O.
and its value at any time in the past
must be exactly 1.00000000000..
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Standard Model circa 1990
Hot Big Bang from Cosmic Background Radiation
(CMB)
Horizon and flatness suggest inflation
Inflation demands that O 1 very precisely
But OB lt .05 from light element nucleosynthesis
Where is the other gt 95 of the mass?
DARK MATTER
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Galactic Rotation Curves
For a star of mass m a distance r from the
center of a galaxy, where the total mass
interior to r is M(r)
mv2/r GM(r)m/r2
so that we would expect
v GM(r)/r ½ so that v should go like r -½
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Oscillations on many scales
Source Wayne Hu background.chicago.edu
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Early Universe Acoustics
Sound speed cs vw v(p/?) c/v3
Density fluctuations
are they random (Gaussian, scale-independent?)
Measure cross-correlation in spherical harmonics
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CMB Anisotropy Power Spectra Dependence on
Cosmological Parameters
Angular Scale
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0.5
0.2
2
6000
4000
2000
6000
Anisotropy Power (µK2)
4000
2000
0
2
10
40
100
200
400
800
1400
Multipole moment
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Power Spectrum
cosmic variance limited for llt354
S/Ngt1 for llt658
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The Top Ten
to 13.7 .2 Gyr
tdec 379 8 kyr zdec 1089 1
Tcmb 2.725 .002 K
m? lt .023 eV
ns 0.93 .03
tr 180 100 Myr zr 20 10
Ho 71 4 km/s-Mpc
Otot 1.02 .02
O? .73 .04
? Om .27 .04
Ob .044 .004
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Fire and Ice by Robert Frost
Some say the world will end in fire Some say in
ice. From what I've tasted of desire I hold with
those who favor fire. But if it had to perish
twice, I think I know enough of hate To know that
for destruction ice Is also great And would
suffice. 
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