Older larger colder less energetic now Big Bang Prediction of Cosmic Microwave Background radiation λ emitted 1 μ m T emitted 3000 K R observed 1000 R emitted ID: 788606
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Slide1
Uncovering the origin of the universe
Older ….. larger … colder ….less energetic
now
Big Bang
Slide2Slide3Slide4Prediction of Cosmic Microwave Background radiation
λemitted = 1 μ
mTemitted = 3000 K
Robserved = 1000Remitted
λobserved = ?
Tobserved = ?
Slide5Comsat communication antenna
– calibrated 1965
see p88 – 89 of textbook
Slide6Cosmic Microwave Background Radiation
Slide7Slide8The sky at different wavelengths
Visible
Near infrared
Far infrared
Slide9Spectrum observed by Cosmic Background Explorer satellite (COBE)
Slide10The Cosmic Microwave Background - key points
CMB is the principal piece of evidence for the Big BangTheory predicts that radiation of λ ≈ 1
μm filled the universe 300,000 years after the Big BangRadiation is observed, filling the universe, but λ has stretched to 1mm
λobserved = 10-3 = 1000 = 1+z
λemitted 10-6 so
z =1000 for the CMB – the ultimate red shift; the furthest back in time that we can seeRadiation is very nearly uniform – shows that it originated from a (nearly) uniform universeEvidence that CMB really is the ‘remains of the Big Bang’:
Comes from everywhere
Wavelength agrees with predictions
Has the expected ‘black body radiation’ spectrum