The cosmic microwave background (CMB) radiation detected by Penzias and Wilson at Bell Labs in 1965 has the spectrum of a blackbody, with an observed peak at λ = 1 mm. It is believed that when the light was emitted the spectrum peaked at a wavelength of λ = 1000 nm (close to the peak of the spectrum of the Sun). The cosmological redshift is directly connected to the scale factor that we discussed So, the CMB gives us a picture of the infant universe, when the universe was just a fraction of its current size. By what factor was the universe smaller when the CMB was emitted than it is today? The emission of the CMB occurred when the universe was 389,000 years old. Its current age is 13.7 billion years. If we compare the universe to a person of age 80, from what age (in days) do our ‘baby pictures’ come? 2. Z = (lambda_observed - lambda_emitted)/lambda_emitted a(t) = 1 + z 3. I just got out of my second exam today and I am fairly retarded at the moment. Can someone get me started?