Explorations: Introduction to Astronomy (Arny), 6th Edition

Chapter 18: Cosmology

Questions for Review

1
Why do astronomers think that the Universe is expanding?
2
What is meant by a cosmic horizon?
3
What is Olbers' paradox?
4
What is the cosmic microwave background? What is its origin?
5
Why do astronomers think that the early Universe was hot and dense?
6
What is meant by the age of the Universe? How old is it? How is its age found?
7
How was helium formed from hydrogen in the early Universe?
8
What explanation do astronomers offer for why the relative abundance of hydrogen and helium is uniform?
9
Is our cosmic horizon the same as that of beings in another galaxy? Why?
10
What is meant by inflation in cosmology?
11
What is the Big Bang? What are some of its properties?
12
What problems of the Big Bang theory are resolved by inflationary models?
13
What is meant by open and closed universes?
14
How do the shapes of open, closed, and flat universes differ? How does their energy content differ?
15
What is "unified" in grand unified theories?
16
What is meant by dark matter?
17
What role does the cosmological constant play in cosmology? What evidence makes astronomers think it may exist?
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