Chapter 30 Section 4 Chapter 30 Section 4 HandoutHandout

The Big Bang TheoryThe Big Bang Theory

11

What is cosmology?What is cosmology?The study of the origin, structure, and future The study of the origin, structure, and future

of the universe.of the universe.

22

Like all scientific theories, the theories Like all scientific theories, the theories about the origin and evolution of the about the origin and evolution of the universeuniversemust constantly be tested against new must constantly be tested against new

observations and experiments.observations and experiments.

33

Many current theories of the universe Many current theories of the universe began with observations madebegan with observations made less than 100 years ago.less than 100 years ago.

44

What did Hubble discover near the end of What did Hubble discover near the end of the 1920’s?the 1920’s?The spectra of galaxies were shifted toward The spectra of galaxies were shifted toward

the red end of the spectrum.the red end of the spectrum.

55

What did Hubble find out about the most What did Hubble find out about the most distant galaxies?distant galaxies?They showed the greatest red shift and thus They showed the greatest red shift and thus

were moving away from Earth the fastest.were moving away from Earth the fastest.

66

What do the spectra of distant galaxies What do the spectra of distant galaxies collected today say about Hubble’s original collected today say about Hubble’s original finding?finding?They confirm Hubble’s original findings.They confirm Hubble’s original findings.

77

Define the big bang theory.Define the big bang theory.All matter and energy in the universe was All matter and energy in the universe was

compressed into an extremely small volume compressed into an extremely small volume that about 14 billion years ago exploded and that about 14 billion years ago exploded and began expanding in all directions.began expanding in all directions.

88

If you trace the expanding universe back If you trace the expanding universe back in time, what would you find?in time, what would you find? that all mater was close together at one time.that all mater was close together at one time.

99

In terms of expansion, what is true of the In terms of expansion, what is true of the universe today?universe today? it is still expanding and the galaxies continue it is still expanding and the galaxies continue

to move away from one another.to move away from one another.

1010

What is cosmic background radiation?What is cosmic background radiation?Low levels of energy evenly distributed Low levels of energy evenly distributed

throughout the universe.throughout the universe.

1111

When do astronomers think cosmic When do astronomers think cosmic background radiation formed?background radiation formed? it formed shortly after the big bang.it formed shortly after the big bang.

1212

What would the universe have been like What would the universe have been like soon after the big bang compared with soon after the big bang compared with now?now?The universe after the big bang would have The universe after the big bang would have

been extremely hot and would have cooled to been extremely hot and would have cooled to a great extent by now.a great extent by now.

1313

What is the temperature of the energy of What is the temperature of the energy of the background radiation from the big the background radiation from the big bang?bang?only about 3only about 3ooC above absolute zero, the C above absolute zero, the

coldest temperature possible.coldest temperature possible.

1414

What are the ripples in the cosmic What are the ripples in the cosmic background radiation?background radiation?They are irregularities in the cosmic They are irregularities in the cosmic

background radiation, which were caused by background radiation, which were caused by small fluctuations in the distribution of matter small fluctuations in the distribution of matter in the early universe.in the early universe.

1515

What may the ripples in the cosmic What may the ripples in the cosmic background radiation indicate bout the background radiation indicate bout the early universe?early universe?The first stages in the formation of the The first stages in the formation of the

universe’s first galaxies.universe’s first galaxies.

1616

Analyzing the ripples in cosmic Analyzing the ripples in cosmic background radiation tells us that the kinds background radiation tells us that the kinds of matter that humans, the planets, the of matter that humans, the planets, the stars, and matter between stars are made stars, and matter between stars are made ofofmakes up only 4% of the universe.makes up only 4% of the universe.

1717

What is the type of matter called that does What is the type of matter called that does not give off light?not give off light?Dark matterDark matter

1818

What is dark energy?What is dark energy?Scientist think that it acts as a force that Scientist think that it acts as a force that

opposes gravity.opposes gravity.

1919

Recent evidence suggests that distant Recent evidence suggests that distant galaxies aregalaxies are farther from Earth than current theory would farther from Earth than current theory would

indicate.indicate.

2020

Because of dark energy, the universe’s Because of dark energy, the universe’s rate of expansion.rate of expansion.seems to be accelerating.seems to be accelerating.