Big Bang Notes:
The universe began as a single cosmic explosion about 14 billion years ago.
Newton’s Static Universe
Olber’s Paradox
After the Big Bang
Evidence of the Big Bang
Major Piece of Evidence #1: Background Radiation
Major Piece of Evidence #2: Expanding Universe
Major Piece of Evidence #3: Temperature
Expanding Universe
Big Bang theory leads to two possible futures for the Universe:
Open Universe
Closed Universe
Right here on Earth:
The universe began as a single cosmic explosion about 14 billion years ago.
Newton’s Static Universe
- Universe is static and composed of an infinite number of stars that are scattered randomly throughout an infinite space.
- Universe is infinitely old and will exist forever without any major changes.
Olber’s Paradox
- Using this logic, the sky should be the average brightness of all of these stars; the sky should be as bright as the sun, even at night.
After the Big Bang
- Gravity pulls matter into small clumps
- Clumps become huge clouds of dust and gas
- Clouds become solar systems and galaxies
Evidence of the Big Bang
Major Piece of Evidence #1: Background Radiation
- Energy left over from the Big Bang is evenly spread throughout the universe.
- This background radiation is observable!
Major Piece of Evidence #2: Expanding Universe
- Every object in the universe is moving away from the center.
- Think of waves spreading out from where you drop a pebble into a pond.
Major Piece of Evidence #3: Temperature
- The temperature in deep space is around 3° K.
- Leftover heat from Big Bang keeps space just above absolute zero
Expanding Universe
- Objects near the very edge of the universe are the oldest
- The most distant known objects in the universe are over 12 billion light years from the Earth
Big Bang theory leads to two possible futures for the Universe:
- Open Universe
- Closed Universe
Open Universe
- The universe will continue to expand. All stars will die as the last of their energy is released. Eventually, all matter will be reduced to single atoms moving away from each other. There will be nothing left...The end.
Closed Universe
- Gravitational attraction between objects will cause the expansion of the universe to slow and, eventually, come to a halt. Gravity will then begin to pull everything back to the center of the universe.
- Eventually, all matter and energy will again condense into a single point, possibly no larger than a dime. Another Big Bang will occur and the formation of the universe will begin all over again.
Right here on Earth:
- Whatever happens to the universe, we are pretty lucky here on earth.
- We have the two main requirements for life:
- Liquid water
- Protection from UV radiation
- Perhaps elsewhere in the universe, other planets or moons do, too