Test 1, 2019.4.22<br>
Astronomy 123</br>
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Version: April 20, 2019<br>
<a href="midterm1.pdf">Sample Test</a>
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Multiple Choice Answers:
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A,D,B,E,E,C,D,B,D,A,A,A,B,D,C
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Details:<p>
INTRODUCTION<p>
<ul>
<li>Cosmology: Define cosmology. How has cosmology (as a science) evolved
from the time of the Greeks to current times? 
<li>What makes a <i>model</i> scientific? Contrast science and philosophy.
<li>Compare the terms (and use of the terms) Universe and universe. 
<li>Basic Observations of cosmology:
<ul>
<li>List the basic observtions which led to the Big Bang Theory. 
<li>Explain how
each piece of data supports the Big Bang theory.
<li>Briefly describe the Big Bang theory. 
Is the Big Bang theory on secure ground. What why or why not.
<li>What is Hubble's Law? How was Hubble's Law discovered?
<li>Describe cosmological redshift.
<li>What is the <i>naive</i> interpretation
of Hubble's Law. How does the Principle of Mediocrity influence our
interpretation of Hubble's Law? Describe the currently accepted notion for
Hubble's Law.
<li>For Homework 1, your determination of the distances to the given galaxies
relied on the assumption that our Universe is flat among other assumptions.
How would your results change if the Universe is open (saddle-shaped)?
<li>Cosmic Microwave Background Radiation (CMBR): Describe the CMBR. When 
was the CMBR producedarise? Describe the  
properties of the CMBR. 
<li>Describe the horizon problem. Describe why the CMBR's properties lead to 
the horizon problem.
<li>The chemical composition of the normal matter in the 
Universe is roughly 90 % hydrogen and ~ 10 %
helium, everyting else heavier than helium is referred to as a <i>metal</i>
and comprise only a small part of the Universe. 
<li>Describe the makeup of the Universe. Be sure to consider both matter and
dark energy. 
</ul>
<li>Cosmological Principles:<ul>
<li>Principle of Mediocrity: Describe the principle of mediocrity.
<li>Give and describe examples of how the principle of mediocrity seemed to
be violated at different times during history. Be sure to mention how 
different experimental results (that pertain to the principle of 
mediocrity) were misinterpreted in the past. 
Has it been violated yet? 
<li>Cosmological Principle: Describe the cosmological principle. 
<li>Describe the meanings of homogeneity
and isotropy. Give simple examples that illustrate each concept. 
<li>The Universe is clearly not bland and uniform, in what sense is
the cosmological principle valid? 
<li>Perfect Cosmological Principle, what is it? Is it currently considered by
astronomers when they model the Universe? It is not, what are some reasons why
the Perfect Cosmological Principle is not in favor? What is the Cosmological
Constant? It was first proposed by Einstein, why? Why did Einstein withdraw his 
suggestion? Has this idea returned to favor today? 
<li>Anthropic Principle, What is the Anthropic Principle? 
</ul>
<li>What is a light year? 
</ul>
</ul>
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World Views of the Universe
<ul>
<li>Describe Olbers's Paradox and the resolution of the
paradox. That is, what are the assumptions which underlie Olbers's Paradox
and must they be modified to resolve the paradox?
How can the Big Bang resolve Olbers' Paradox?
<li>Describe the Friedman models for the Universe. What assumption did 
Friedman make when finding his models for the Universe? Was this assumption
valid? 
<li>What is meant by spacetime? In terms of spacetime, describe each of
Friedman's models for the Universe.
<li>Interpret and explain the Hubble Law in the context of an expanding
Universe.
How does the cosmological redshift fit in with the Hubble Law?
<li>Describe Hubble's law and how it changes for distant galaxies. Explain how
Hubble's law as determined by distant galaxies can show us ultimate evolution
of the Universe.
<li>What is the Cosmological Constant (Lambda)? 
<li>What is the Horizon Problem? 
</ul>
Black Holes, and Miscellaneous
<ul>
<li> What are black holes? Have black holes been observed, if so, where?
<li> What are blackbodies and what is Wien's Law? Why are black bodies of
interest to astronomers?
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