Beyond the Big Bang

1
Lecture 10 Beyond the Big Bang
Big Bang
Is the Big Bang the last word?
2
Problems with the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

Beyond the Big Bang
Is the Big Bang the last word?
3
Problems with the Big Bang

• The Flatness Problem

At the present time, the density parameter is
close to 1
Beyond the Big Bang
O0 1.0 0.02
At earlier times, the variation of the density
parameter from 1 gets less. For example, at the
time of nucleosynthesis

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

Onuc 1.0 10-14
At the Planck time 5X10-44 sec the density
parameter is extremely close to 1
OPlanck 1.0 10-60
Is there a natural explanation for something in
nature being this closely balanced?
4
Problems with the Big Bang
2. The Horizon Problem
Horizon
Surface of last scatter
Beyond the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

Corresponds to about 2 degrees of arc today.
How can the CMB be so uniform when points on it
more than 2 degrees apart are out of contact with
each other?
5
Problems with the Big Bang
3. The Structure Problem
Beyond the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

What produced the large-scale structure in the
universe and the temperature fluctuations in the
CBR?
6
Problems with the Big Bang
4. The Monopole Problem
e-
The electron is an electric monopole
Beyond the Big Bang
A magnet is a magnetic dipole

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

X
X
If you break a magnet in two, do you get magnetic
monopoles?
No! You get two smaller magnetic dipoles!
But can magnetic monopoles exist?
Maybe. If the universe has GUTS?
Diversion to elementary particle physics ?
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The Standard Model for Elementary Particle Physics
Leptons
Quarks
2/3 -1/3 -1 0
Quicky Survey of Elementary Particle Physics
I II III
Bosons Fermions
8
The Standard Model for Elementary Particle Physics
The Four Fundamental Forces of Nature
Quicky Survey of Elementary Particle Physics
highest lab energy
grand unification?
room temperature
9
The Standard Model for Elementary Particle Physics
Grand Unification
Quicky Survey of Elementary Particle Physics
10
Supersymmetry
Quicky Survey of Elementary Particle Physics
11
Problems with the Big Bang
4. The Monopole Problem
e-
The electron is an electric monopole
Beyond the Big Bang
A magnet is a dipole

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

If you break a magnet in two, do you get magnetic
monopoles?
No! You get two smaller magnets!
But can magnetic monopoles exist?
Maybe. If the universe has GUTS?
Grand Unification Theories (GUTS) predict
magnetic monopoles!
Where are the monopoles?
12
Problems with the Big Bang
5. The Hierarchy Problem
Beyond the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

GUTS predict that lower mass objects will have
their masses increased to GUT level energies!
Why such a huge gap between important energy
scales? And why arent elementary particles much
much heavier?
13
Problems with the Big Bang
6. The Gravity Problem
Beyond the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

Why is the Gravitational Force so weak?
14
Possible Big Bang Solutions

• Inflation
• Supersymmetry
• Strings
• Branes

Beyond the Big Bang
15
Inflation
Beyond the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

16
What is inflation?

• Inflation is a cosmological model in which the
  observable Universe undergoes enormous increase
  in size between about 10-35 and 10-32 seconds
  after the Big Bang.
• In that short time, the size of the observable
  universe increases by a factor of about 1043. (It
  has since expanded by another 1026)
• Inflation is a modification of standard Big Bang
  cosmology
• It was originated by Alan Guth and modified by
  several others.
• Inflation is a prediction of grand unified
  theories in particle physics that was applied to
  cosmology it was not just invented to solve
  problems in cosmology

Beyond the Big Bang
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Without inflation?

• At t10-35 s, the observable Universe expands
  from about 1 cm to about 1028 cm today.

Beyond the Big Bang
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With inflation?

• At t10-35 s, the observable Universe expands
  from about 10-42 cm to about 1028 cm today, while
  the universe within the horizon expands from
  about 10-25 cm to what it is today.

Beyond the Big Bang
1028 cm
10-42 cm
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Inflation

• How does inflation solve some of the Big Bang
  problems?
• It presumes another component other than
  radiation or matter that dominates. This
  component acts much like an early era
  cosmological constant in that it causes an
  acceleration of expansion.
• With this component, an initial curvature
  parameter not even nearly equal to 1 will rapidly
  become equal to 1 as time progresses.

Beyond the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

20
Inflation
Beyond the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

seconds
10-36
10-32
10-34
10-30
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Inflation

• How does inflation solve some of the Big Bang
  problems?
• It presumes another component other than
  radiation or matter that dominates. This
  component acts much like an early era
  cosmological constant in that it causes an
  acceleration of expansion.
• With this component, an initial curvature
  parameter not even nearly equal to 1 will rapidly
  become equal to 1 as time progresses.
• With this component, the surface of last scatter
  (to be) is much smaller than the horizon (10-44 m
  compared to 10-28 m), allowing the radiant energy
  within the surface of last scatter to thoroughly
  reach thermodynamic equilibrium, i.e, the same
  temperature.

Beyond the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

Horizon
Surface of last scatter
22
Inflation

• How does inflation solve some of the Big Bang
  problems?
• It presumes another component other than
  radiation or matter that dominates. This
  component acts much like an early era
  cosmological constant in that it causes an
  acceleration of expansion.
• With this component, an initial curvature
  parameter not even nearly equal to 1 will rapidly
  become equal to 1 as time progresses.
• With this component, the surface of last scatter
  (to be) is much smaller than the horizon (10-44 m
  compared to 10-28 m), allowing the radiant energy
  within the surface of last scatter to thoroughly
  reach thermodynamic equilibrium, i.e, the same
  temperature.
• Large scale structure has its origins in tiny
  quantum fluctuations in the energy distribution
  before inflation.

Beyond the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

23
Inflation

• How does inflation solve some of the Big Bang
  problems?
• It presumes another component other than
  radiation or matter that dominates. This
  component acts much like an early era
  cosmological constant in that it causes an
  acceleration of expansion.
• With this component, an initial curvature
  parameter not even nearly equal to 1 will rapidly
  become equal to 1 as time progresses.
• With this component, the surface of last scatter
  (to be) is much smaller than the horizon (10-44 m
  compared to 10-28 m), allowing the radiant energy
  within the surface of last scatter to thoroughly
  reach thermodynamic equilibrium, i.e, the same
  temperature.
• Large scale structure has its origins in tiny
  quantum fluctuations in the energy distribution
  before inflation.
• Grand unification energies (temperature) existed
  before and during inflation and many monopoles
  were created. But their density diminished to an
  imperceptible level by the end of the
  inflationary period by which time GUT symmetry
  was broken.

Beyond the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

24
Inflation

• How does inflation solve some of the Big Bang
  problems?
• The hierarchy problem is solved by Supersymmetry.

Beyond the Big Bang

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem

25
Inflation

• How does inflation solve some of the Big Bang
  problems?
• The hierarchy problem is solved by Supersymmetry.
• The gravity problem may be solved by String
  Theory.

Beyond the Big Bang
Next Lecture

• The Flatness Problem
• The Horizon Problem
• The Structure Problem
• The Monopole Problem
• The Hierarchy Problem
• The Gravity Problem