Astronomy 123: Third Homework Assignment

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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 radial velocity of galaxies 1 and 2.
This tutorial might help
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
Recent evidence suggests that the Universe is filled with something termed "Dark Energy". Dark Energy is not the same as Dark Matter. This question is only about Dark Energy.:
Explain how the "top-down" scenario for the formation of structure (e.g. galaxies, clusters of galaxies) in the Universe differs from the "bottom-up" scenario.
Do some research on the concept of "Modified Newtonian Dynamics" or MOND. Discuss the basic idea of MOND and state whether or not you think its a credible alternative to the need for Dark Matter, which we still have not yet detected.