Highlights of Cosmology Physics 114 Spring 2004 – S. Manly References and photo sources: Ned Wright Hubble space telescope SNAP NRC presentation –

Edwin Hubble ( ) Discovered the expanding universe in 1929

Hubble – Mpc= 1 Megaparsec = 3x10 22 m 1 light year = 9x10 15 m Doppler shift for light waves

Type Ia SNe from Riess, Press and Kirshner (1996) Slope is the hubble constant which measures the expansion rate of the universe Measured to be approx. 70 km/sec/Mpc Know the expansion rate, one can extrapolate back in time and find the age of the universe to be something like 13 billion years.

The universe is approximately smooth and isotropic on a large scale Peacock and Dodds (1994, MNRAS, 267, 1020)

Penzias and Wilson discovered the Cosmic Microwave Background in 1964 – This is the radiation from the big bang redshifted to microwave frequencies thru 14 billion years of expansion - uniform and isotropic! Actually from t=100,000 years when temp was 3000 degrees and H was formed and radiation could stream freely

Well … the universe is not completely isotropic and homogenous. Otherwise we would not be here! WMap data on the temperature fluctuations in the CMB Show movie of why structure matters

The curvature of spacetime, i.e. the geometry of space, determines the future of the universe. The curvature is determined by the amount of mass and energy in the universe. These are possible a(t) vs. t curves for the expansion of the universe

Consistent with flat Universe dominated by a vacuum energy density which provides 73 percent of the total density of the Universe. Another 23 percent of the density is dark matter. Only 4 pecent of the density is ordinary matter made of protons and neutrons!

Supernova data from SNAP NRC presentation

1/20 The search for dark matter and to find clues as to the nature of dark energy are among the hottest topics in science today!