Origin of the Universe • Steady state theory – • belief that everything is the same as it always was • as it expands, new matter is formed to keep the density of the universe uniform ** evidence suggests that the universe was different in the past Oscillating model – • Expansion followed by contraction with the process then beginning again Big Bang theory - The universe is and will always expand.
What is the Big Bang Theory? • The most popular theory about the origin and evolution of our universe • Like all scientific theories, depending on the outcome of observations, it may need to be changed
The Big Bang: • Occurred 13.7 billion years ago • The universe we can see today was only a few millimeters across • Has since expanded from this hot dense state into the vast and much cooler cosmos • The universe contains all of the galaxies, including the Milky Way Galaxy, where we live
Support for the Big Bang Model The Big Bang Model is supported by a number of important observations: • The expansion of the universe/ Red Shift • The abundance of the light elements H, He, Li • The cosmic microwave background radiation
Expansion of the Universe Raisin Bread Dough Model In 1929, Edwin Hubble announced that his observations of galaxies showed that they were all moving away from us with a speed that was proportional to their distance from us. The more distant the galaxy, the faster it was moving away from us
Doppler Shift Sound • Light
Abundance of the light elements H, He, Li Helium • One second after the Big Bang, the temperature of the universe was roughly 10 billion degrees • During the first three minutes of the universe, most of the Hydrogen combined to make Helium. Trace amounts of Lithium were also produced at this time. • We know that the amount of hydrogen, helium and lithium stays the same no matter where we look in the universe
Cosmic Microwave Background Radiation • The cosmic microwave background (CMB) radiation is the radiant heat left over from the Big Bang • The existence of the CMBs was first predicted by Ralph Alpher, Robert Herman, and George Gamow in 1948. It was first observed in 1965 by Arno Penzias and Robert Wilson
Galaxies • Galaxies and stars formed within a few billion years after the Big Bang • A galaxy is any large collection of stars that can be recognized as a distinct physical entity • A galaxy has between ten million (dwarf galaxies) to 100 trillion stars • There are more than 100 billion galaxies in the universe
The Milky Way Galaxy • Our home galaxy • About 100,000 light years across • 2 Main Spiral Arms • It has over 200 billion stars • There is a supermassiveblack hole at the center • It's part of the Virgo Supercluster, a grouping of galaxies within 150 million light years
The Milky Way Galaxy You Are Here
Checkpoint: • Do you think these are actual pictures taken or artist interpretations? Explain.
Astronomical Address • Sam and Sally Student • 112 Elm Street • Byfield • Massachusetts • USA • Earth (Third planet from the sun) • The Solar System • Milky Way Galaxy • Virgo Supercluster • The Universe
Expansion of Universe • http://www.youtube.com/watch?v=iCI8K9mD_yU • Birth of our solar system • http://www.youtube.com/watch?v=B1AXbpYndGc&feature=fvw • Hadron collider • http://www.youtube.com/watch?v=jlY4OBNo1T8&feature=related