NEED FOR INFLATION.

1
NEED FOR INFLATION.

• Horizon Problem
• Temperature of the CMB uniform in regions that
  could never have communicated with one another.
• Flatness Problem
• Why is the universe so close to being flat? If
  we now have W 0.1, then W -1 10-15 at t 1 s
  and 10-24 at t 1 nanosecond (Extreme fine
  tuning).
• Smoothness Problem
• How did the fluctuations in the CMBwhich
  eventually resulted in large-scale
  structure...emerge?
• Monopole Problem
• Many are predicted, but none are detected.
  (OKmaybe one!).

2
WHAT IS INFLATION?

• False vacuum
• The initial, high-energy phase of the universe,
  prior to the Grand Unified Theory GUT phase
  transition in which quarks are formed.
• At 10-34 s, the true vacuum, a lower-energy
  phase corresponding to the current universe,
  emerges and becomes stable.
• Supercooling
• Universe may become stuck for a time in the
  false vacuum state even when the true vacuum is
  more stable.
• The locked-up energy density generates a very
  large, negative cosmological constant.
• Exponential expansion
• Universe doubles in size every 10-34 s. By 10-32
  s it has inflated by a factor of 2100 1.3 x
  1030 (diameter of a proton inflates to 10 light
  years!!).
• By the end of this period the false-vacuum energy
  density has been released, heating the universe
  to 1027 K, initiating the normal Big Bang.

3
RESULTS FROM INFLATION.

• Horizon Problem
• All portions of the visible universe were once in
  contact. Thus, there is no horizon problem.
• Flatness Problem
• No matter what the initial curvature was, it will
  have been stretched out to very nearly flat.
• Monopole Problem
• Monopoles were diluted away.
• Smoothness Problem
• Clumps arise from quantum fluctuations caught
  "in flagrente delicto" by inflation.