Speaker: James Fradgley

What is a photon? How are photons produced? Doppler Effect – red shift. Spectral broadening from temperature. Cosmological red shift. Estimating the density of a cloud. Comparing line strengths of closely related meta-stable lines. Estimating the temperature of a cloud. The Lyman Alpha Forest. When the universe became neutral and then became re-ionised. Cosmic microwave background (CMB) radiation.