Galaxies and Cosmology

09.27.07 / 09.28.07

Types of Galaxies

• Spiral – Including Barred Spiral

• Elliptical• Irregular

M8112 million light years away

M8212 million light years away

NGC130046 million light years away, 85,000 light years across

NGC 131680 million light years away

Edwin Hubble

• In 1929, discovered most galaxies have a “red shift”

• Like the Doppler effect when a car drives past

• Expanding universe seemed only plausible explanation

Red or blue shift?• Most of the universe has a red shift• The Andromeda galaxy has a blue shift• Spiral galaxies show a slight blue shift on the side

spinning toward us and a red shift on the side spinning away

Big Bang

Hubble Ultra Deep Field10,000 galaxies, up to 13 billion light years away

Close up of HUDF

HUDF and baby galaxies

- evidence for big bang

- evidence that galaxies form by

combining

Relativity

• Einstein’s theory of relativity indicated an expanding or contracting universe– He believed in the steady state theory– So, he created the cosmological constant– Edwin Hubble’s discovery of red shift cause

Einstein to retract his constant– He called the constant his greatest mistake

Distribution of elements

• In 1948, George Gamow used the big bang theory to predict the distribution of elements in the universe

• Measurements have since shown he was essentially accurate

Penzias and Wilson

• Drs. Penzias and Wilson accidentally discovered cosmic microwave background radiation in 1965

• Awarded Nobel Prize for Physics in 1978• The radiation was predicted in 1948 by

George Gamow

Cosmic Background Explorer (COBE)launched in 1989

George Smoot and John Mather awarded Nobel Prize in 2006

WMAPlaunched 2001

The universe is flat?• A flat universe has no center and no end• Parallel lines stay parallel and never return• Tested many times and confirmed by WMAP using

variations in CBR

See: “WMAP Cosmology 101: Shape pf the Universe” at http://map.gsfc.nasa.gov/m_uni/uni_101shape.html