Highlights of Cosmology

Physics 114

Spring 2004 – S. Manly

References and photo sources:

Ned Wright http://www.astro.ucla.edu/~wright/cosmolog.htm

Hubble space telescope

http://map.gsfc.nasa.gov/m_or/mr_media2.html

SNAP NRC presentation – http://www.supernova.lbl.gov

Edwin Hubble (1889-1953)

Discovered the expanding universe in 1929

v

v0 c

c

Hubble – 1929

1 Mpc= 1 Megaparsec = 3x1022 m

1 light year = 9x1015 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

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