Astronomy II (Astr 1020)
Spring 2008
Prof Richard Ignace
HOMEWORK #6
Notes:
You will need a calculator, a pencil, and a standard scantron.
Each question has one correct answer. Choose the best answer for each. Mark your answer on the scantron.
This homework is due at the beginning of class on April 15. Late homeworks will not be accepted.
1. Olbers’ paradox is best summarized by which of the following?
a) If the Universe has an infinite age, why hasn’t it collapsed?
b) If the Universe is finite in space, does it have an edge?
c) If the Universe is finite in time, what occured before the Big Bang?
d) If the Universe began as a single “point,” how can it be infinite?
e) Why is the night sky dark?
2. The Cosmological Principle implies which one of the following are valid:
a) The Doppler effect and Euclidean geometry
b) Newtonian mechanics and relativity
c) Homogeneity and isotropy of the Universe
d) Hubble’s Law and the curvature of the Universe
e) Great taste and less filling
3. Why does the presence of quasars at great distances (and only at great distances) from our galaxy
imply that the Perfect Cosmological Principle is not valid?
a) The distances and radial velocities for the quasars violate the Hubble relation.
b) They show that the Universe was generally different at an earlier time.
c) The quasars are so bright that no known energy source can possibly power them.
d) The great distances to the quasars allow us to observe gravitational lensing effects.
e) There is no evidence that galaxies have formed at such great distances.
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