Due Monday Feb 8 at 11 pm
Submit your assignment through Canvas.
Note that the purpose of the homework assignments in this class is for you to do research outside of class about some of the various topics discussed in class so that you can get more learning depth about the issues. Research based questions should be answered by consulting a number of sources and responding with a fairly complete answer. Cut and paste is easily detected so make sure you synthesize an answer IN YOUR OWN WORDS!
In addition, you can work on this homework assignment in group sizes as large as 4. Collaborative research and editing is an important skill to learn so perhaps this particular class might have some benefit down the road to help you develop this skill.
For each group, submit only one homework document through Canvas with all group member names on it.
- Question 1: What was the COBE mission of NASA and what were its main results?
What is the WMAP mission and how has it improved upon the COBE results?
- Question 2:
a) Research and summarize the Shapley-Curtis debate and its implications on the overall
size of our Galaxy and the size of the Universe.
b) What kinds of evidence
did Shapely use to promote his basic premise that our Galaxy was
in fact, the entire Universe?
- Question 3:
Suppose that I take a spectrum of two galaxies.
- In
Galaxy 1 I observe that the hydrogen line has a wavelength of 8204 angstroms.
- In Galaxy 2 I observe the hydrogen line has a wavelength of 6549 angstroms.
I know from laboratory measurements that the rest wavelength of this hydrogen line is 6563 angstroms. Given this data, compute the radial velocity of galaxies 1 and 2 using the method described in this tutorial
- Question 4: Google (and don't be lazy and rely on the usually erroneous and incomplete Wikipedia) on "Andrew Mckellar Microwave Background". McKellar actually detected the MWB in 1941 (!) but did not realize it at that time. Based on your research about the nature of the observations, speculate why you think he was unable to put his data together to claim initial discovery and hence a future Nobel prize.
- Question 5: Explain how the currently observed density of deuterium is a sensitive probe of the baryon density of the early Universe and why a high abundance of deuterium indicates a LOW density universe.
- Question 6: For particle reactions, the conservation rules of Charge (C), Lepton number (L), and
Baryon number (B), all have to hold, otherwise the reaction can't occur. Show that the
reactions below following these rules (i.e. show that C, L and B are the same after
the reaction as before the reaction)
anti-neutrino+proton 
neutron+anti-electron
neutrino + neutron proton + electron
a) Research and summarize the Shapley-Curtis debate and its implications on the overall size of our Galaxy and the size of the Universe.
b) What kinds of evidence did Shapely use to promote his basic premise that our Galaxy was in fact, the entire Universe?
Suppose that I take a spectrum of two galaxies.
- In Galaxy 1 I observe that the hydrogen line has a wavelength of 8204 angstroms.
- In Galaxy 2 I observe the hydrogen line has a wavelength of 6549 angstroms.
I know from laboratory measurements that the rest wavelength of this hydrogen line is 6563 angstroms. Given this data, compute the radial velocity of galaxies 1 and 2 using the method described in this tutorial
neutron+anti-electron
neutrino + neutron proton + electron