Use these questions to test your understanding. If you get them wrong, you will be linked back to the relevant part of the notes.
Be sure you study them thoroughly (don't just get a quick fix for your mistake) so your overall understanding is improved.
1. The 3 degree cosmic background radiation originated when
a. the Universe got started in the Big Bang
b. the first stars began radiating
c. active galactic nuclei heated up interstellar dust
d. electrons were captured by protons to make the Universe transparent
e. inflation occurred
2. The contrast in the structure on the 3K cosmic background tells us about
a. what kind of matter formed (fraction of baryonic or nonbaryonic)
b. where the first galaxies are
c. irregularities in the Big Bang
d. how the fundamental forces decoupled
e. where the cold spots are in the Universe
3. Dark matter
c. played a critical role in the merger of galaxies in the early Universe
d. no longer exists in significant quantities
e. glows faintly, allowing it to be observed with modern space telescopes
4. The early stages of development of the Universe
a. are surprisingly well understood through a combination of physics and astronomy
b. are really hard to study because conditions were so extreme
d. may have been either steady state or big bang in nature
e. were a time when a totally different physics operated
5. The cosmic background radiation provides strong evidence that
a. the early Universe was very cold, only 3 degrees above absolute zero
b. stars formed almost immediately in the early Universe
c. the Universe has been expanding steadily forever
d. the Universe evolved from a hot, dense state
e. a lot of energy was produced through hydrogen fusion early in the life of the Universe
6. The cosmic background radiation is visible equally in every direction because
a. we are at the center of the Universe
b. we are not moving fast enough to Doppler shift the background by a large amount
c. we are looking back to when the Universe was young and opaque in every direction
d. the background has been scattered many times and now looks uniform
e. our telescopes are just not powerful enough to see far enough away to detect the nonuniformities
7. Astronomers cannot look back further than when the Universe was 300,000 to 500,000 years
old because
a. before that, the Universe was too crowded with stars
b. photons were not produced until the Universe was 300,000 years old
c. dust in the early Universe absorbed the light
d. the Universe was made of dense, ionized gas that was opaque to light