Today’s Cosmology

• = 1.0 from CMB measurements. We live in a flat Universe.

• <0.3 from extensive observations at various wavelengths. Includes dark matter as well as normal matter and light.

• ~ 0.7 from Type 1a SN observations. Many different theories for “dark energy.” Universe accelerates and is open, even though it is flat.

• Hubble constant = 70 km/sec/Mpc from HST observations. Age of Universe is around 13.7 billion years (WMAP).