Questions for Chapter 23

1. What is antimatter? How were particle-antiparticle pairs created in the early universe? How were they destroyed?

2. Explain what we mean by the Big Bang theory,

3. Make a list of the major eras in the history of the universe, summarizing the important events thought to have occurred during each era.

4. Why can’t our current theories describe the history of the universe during the Planck era?

5. What are the four forces that operate in the universe today? Why do we think there were fewer forces operating in the early universe?

6. What do we mean by inflation, and when do we think it occurred?

7. Why do we think there was a slight imbalance between matter and antimatter in the early universe? What happened to all the antimatter, and when?

8. How long did the era of nucleosynthesis last? Explain why this era was so important in determining the chemical composition of the universe.

9. When we observe the cosmic microwave background, at what age are we seeing the universe? How long have the photons in the background been traveling through space? Explain.

10. How does the existence and nature of the cosmic microwave background radiation support the Big Bang theory?

11. How does the chemical abundance of helium in the universe support the Big Bang theory? Explain.

12. How do measurements of deuterium and lithium tell us about the density of the universe, and why do they suggest that most dark matter consists of WIMPS?

13. Describe each of the three major questions left unanswered by the Big Bang theory without inflation, and explain how inflation answers each of them.

14. How can observations of the cosmic microwave background radiation released when the universe was 380,000 years old tell us about the universe at the much earlier time when inflation occurred? Summarize the geometry, composition, and age of the universe according to observations made to date.

15. Tell the life story of a proton from its formation shortly after the Big Bang to its presence in the nucleus of an oxygen atom you have just inhaled.

16. Is this the only Universe? Explain briefly.

17. Which of the Multiverses do you prefer? Explain one carefully.

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). Explain clearly; not all these have definitive answers, so your explanation is more important than your chosen answer.

18. Although the universe today appears to be made mostly of matter and not antimatter, the Big Bang theory suggests that the early universe had nearly equal amounts of matter and antimatter.

19. According to the Big Bang theory, the cosmic microwave background was created when energetic photons ionized the neutral hydrogen atoms that originally filled the universe,

20. According to the Big Bang theory, most of the helium in the universe was created by nuclear fusion in the cores of stars.

21. The theory of inflation suggests that the structure of the universe today may have originated as tiny quantum fluctuations.

22. We'll never know whether inflation actually happened because our model for inflation doesn't make any predictions we can test.