1. Chapter 30 Section 4 Handout
The Big Bang Theory

2. 1
What is cosmology?
The study of the origin, structure, and future of the universe.

3. 2
Like all scientific theories, the theories about the origin and evolution of the universe
must constantly be tested against new observations and experiments.

4. 3 Many current theories of the universe began with observations made
less than 100 years ago.

5. 4 What did Hubble discover near the end of the 1920’s?
The spectra of galaxies were shifted toward the red end of the spectrum.

6. 5 What did Hubble find out about the most distant galaxies?
They showed the greatest red shift and thus were moving away from Earth the fastest.

7. 6
What do the spectra of distant galaxies collected today say about Hubble’s original finding?
They confirm Hubble’s original findings.

8. 7 Define the big bang theory.
All matter and energy in the universe was compressed into an extremely small volume that about 14 billion years ago exploded and began expanding in all directions.

9. 8
If you trace the expanding universe back in time, what would you find?
that all mater was close together at one time.

10. 9 In terms of expansion, what is true of the universe today?
it is still expanding and the galaxies continue to move away from one another.

11. 10 What is cosmic background radiation?
Low levels of energy evenly distributed throughout the universe.

12. 11 When do astronomers think cosmic background radiation formed?
it formed shortly after the big bang.

13. 12
What would the universe have been like soon after the big bang compared with now?
The universe after the big bang would have been extremely hot and would have cooled to a great extent by now.

14. 13
What is the temperature of the energy of the background radiation from the big bang?
only about 3oC above absolute zero, the coldest temperature possible.

15. 14 What are the ripples in the cosmic background radiation?
They are irregularities in the cosmic background radiation, which were caused by small fluctuations in the distribution of matter in the early universe.

16. 15
What may the ripples in the cosmic background radiation indicate bout the early universe?
The first stages in the formation of the universe’s first galaxies.

17. 16
Analyzing the ripples in cosmic background radiation tells us that the kinds of matter that humans, the planets, the stars, and matter between stars are made of
makes up only 4% of the universe.

18. 17 What is the type of matter called that does not give off light?
Dark matter

19. 18
What is dark energy?
Scientist think that it acts as a force that opposes gravity.

20. 19 Recent evidence suggests that distant galaxies are
farther from Earth than current theory would indicate.

21. 20 Because of dark energy, the universe’s rate of expansion.
seems to be accelerating.