The Cosmic Microwave Background: Discovery and Average Properties

• discovery; Nobel-prize winning 1.5-page paper
• temperature
• spectrum: purely thermal within current limits

The Atomic Age

• microphysics: recombination
  • ionized (plasma) to neutral (gas)
  • opaque to transparent
• surface of last scattering

Cosmic Microwave Background Fluctuations

• the CMB sky, normal contrast
• high-contrast (1000X): CMB dipole
• higher contrast (100,000X):
  • COBE (1995) -- recognized as landmark result
    WMAP (2003): image making: raw, final product
    COBE vs WMAP
  • fluctuations vs angular scale: WMAP power spectrum
  • cool WMAP movies
• physical origin of fluctuations
• polarization: from WMAP