a spectrum of two galaxies.

a spectrum of two galaxies.

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.:

What is evidence for the existence of dark energy and what are some hypothesis as to what it is?


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.

Suppose you were arguing with your friend who believes the Earth is only a few thousand years old.

Outline what points of “common sense” about various features of the Earth that you could use to demonstrate that the Earth must be at least millions of years old.



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