HW 990602

1. Why do astronomers believe that the energy-production region of a quasar is very small?
2. What is a 'supermassive black hole?' What observational evidence suggests that such supermassive black holes might be located at the centers of some galaxies?
3. Explain the difference between a Doppler redshift and a cosmological redshift.
4. Assuming q₀=1/2 and H₀=60km/s/Mpc, how old would the universe be?