Our Evolving Universe
Self Test 12


  1. Spectroscopic studies of distant hydrogen gas clouds have demonstrated the presence of small quantities of deuterium (hydrogen-2).
    1. This is consistent with Hot Big Bang models, but could also be formed in other ways.
    2. This is not consistent with Hot Big Bang models, because we would expect all the deuterium to be converted into helium.
    3. This is very strong support for Hot Big Bang models, because the measured abundance of deuterium is in agreement with the numerical predictions of the model.
    4. This is not a very important observation for cosmology, because all elements other than hydrogen-1 are made in stars.

  2. Measuring Hubble's constant is difficult because
    1. it is hard to measure redshifts accurately enough, so we do not get a good value of v
    2. it is hard to measure relative distances, so our plot of v against d is not a good straight line
    3. it is hard to measure absolute distances (i.e. it is hard to calibrate distance measurements), so our plot of v against d may be a good straight line with the wrong slope
    4. it is hard to find enough objects to study, so our plot does not have very many points on it

  3. We think that the universe is flat (k = 0, or Omega(total) = 1)
    1. based on measurements of the mass in clusters of galaxies
    2. based on measurements of the small spatial variations in temperature of the cosmic microwave background
    3. based on measurements of Hubble's law using supernovae
    4. because that's what's expected in inflationary models

  4. Direct measurements of the density of matter in the universe
    1. give Omega(matter) ~ 1.0, but 99% of it is non-luminous
    2. give Omega(matter) ~ 0.3, but 99% of it is non-luminous
    3. give Omega(matter) ~ 0.1, but 90% of it is non-luminous
    4. give Omega(matter) ~ 0.1, mostly in visible matter such as stars

  5. A non-zero value for the cosmological constant
    1. is suggested by measurements of Hubble's law using supernovae
    2. is expected in Einstein's theory of general relativity
    3. is required by measurements of galaxy rotation curves
    4. all of the above

out of 5.


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