Observational Cosmology

Cosmological Facts

• Expansion of the Universe
• Cosmic Microwave Background (CMBR)
• Hydrogen/Helium abundances

• mass of the Universe
• expansion rate of the Universe (H[now]===>Hubble constant today)
• matter/anti-matter asymmetry
• large scale structure of the Universe
• ...

The primary observational facts are the first three results. We will concentrate on the first two here. The other results will be discussed when appropriate. However, before we move on to the main topics, let us consider something known as Olbers's Paradox