THEORIES OF UNIVERSE

FORMATION

Studying Space

• Cosmology – the study of the origin, structure, and future of the universe

• Astronomers study planets, stars, and galaxies

• Cosmologists study the universe as a WHOLE

Origin of the Universe

• Several models of its origin have been proposed.

• Steady State Theory

• Oscillating Theory

• Big Bang Theory

• Parallel Universe Theory

Steady State Theory

• It suggests that the universe always has been the same as it is now.

• The universe always existed and always will.

• As the universe expands, new matter is created to keep the overall density of the universe the same or in a steady state.

Oscillating Theory

• In this model, the universe began with expansion (Big Bang).

• Over time, the expansion slowed and the universe contracted (Big Crunch).

• Then the process began again, oscillating back and forth (Big Bounce).

Big Bang Theory

• According to this theory, approximately 14 billion years ago, the universe began with an enormous explosion.

• The entire universe began to expand everywhere at the same time and is still expanding today.

Parallel Universe Theory

• According to this theory, there are an infinite number of universes that exist.

• This theory is very new and, therefore, does not have any supporting evidence currently.

Think About It…

• What does it sound like when a train is blowing its whistle while it travels past you?

• The whistle seems to drop in pitch as the train moves away.

• This effect is called the Doppler shift.

• The Doppler shift occurs with light as well as with sound.

The Doppler Shift

• The Doppler shift causes changes in the light coming from distant stars and galaxies.

The Red Shift

• A red shift in the spectrum occurs when objects in space are moving away from Earth.

Evidence for the Big Bang Theory

• Red Shift – things that are farther from Earth are moving faster than those closer to Earth

• Discovered by Edwin Hubble in 1929

• Called Hubble’s Law

** Shows universe is still expanding **

Evidence for the Big Bang Theory

• Cosmic Background Radiation – radiation detected uniformly (the same) from every direction on space

• Believed to be left over from the Big Bang

** Shows universe is still expanding **

Looking Back in Time

• Whether the universe will expand forever or stop expanding is still unknown.

• If enough matter exists, gravity might halt the expansion, and the universe will contract until everything comes to a single point.

Looking Back in Time

• Studies of distant objects in space indicate that an energy, called dark energy, is causing the universe to expand faster.

• Scientists are trying to understand how dark energy might affect the fate of the universe.

REVIEW

Question 1

An explanation based on many investigationsis a __________.

A. lawB. theoryC. hypothesisD. observation

Answer

The answer is B.

Question 2

___________ is detected uniformly in space from every direction; it supports the Big Bang Theory.A. Red Shift B. ObservationsC. Doppler ShiftD. Cosmic Background Radiation

Answer

The answer is D.

Question 3

______________ states the universe will shift back and forth between expanding and collapsing.

A. Big Bang TheoryB. Oscillating TheoryC. Steady State TheoryD. Theory of Relativity

Answer

The answer is B.