Answer Happy

7. The graph below demonstrates the velocity-distance relation for faraway galaxies that Hubble observed in 1931. Velocity Hubble's data (1931) Distance For what follows assume that all the galaxies Hubble observed were young and primarily contained Hydrogen and Helium. (a) The pictures below shows the absorption spectrum of Hydrogen and Helium along with the spectra from two young galaxies - Q and 8 - that Hubble observed in 1931. Spectrum of Hydrogen and Helium Spectrum from galaxy a Spectrum from galaxy Rank the galaxies in order of increasing distance from Earth. Justify your answer. (10 points) (b) Consider the year 1998 and assume that the expansion of the universe is slowing down (i.e it is decelerating). Use the velocity-distance relation for faraway galaxies that Hubble plotted in 1931 to deduce and draw the graph of 1998. Use the spectra of a and 3 from 1931 to deduce and draw the spectra of a and 8 in 1998. (10 points) (c) Consider the year 1998 and assume that the expansion of the universe is the same as it was in 1931. Use the velocity-distance relation for faraway galaxies that Hubble plotted in 1931 to plot the graph of 1998. Use the spectra of a and 3 from 1931 to sketch the spectra of a and B in 1998. (10 points) (d) We know that the expansion of the universe is speeding up (i.e it is accelerating). Use the velocity-distance relation for faraway galaxies that Hubble plotted in 1931 to draw the graph of 1998. Use the spectra of a and 8 from 1931 to draw the spectra of a and B in 1998. (10 points) (e) Desribe the popular hypothesis that is used to explain the accelerated expansion of the universe. (5 points) Hint: If you want to accelerate your car, you must supply energy by stepping on the gas. (Total: 45 points)