An astronomer claims that the large redshifts of all quasars are caused by some new mechanism and not the expansion of the universe. The redshift tells us nothing, he says, about where any quasar is located. Which of the following would be a way to disprove his view of quasars?

Question

Quizplus · Accepted Answer

If quasars were not affected by the expansion of the universe, then there should be cases where a quasar seen in a cluster of galaxies has a different redshift than all the galaxies in the cluster. Finding such a case would disprove the astronomer's view that the redshift of quasars is not due to the expansion of the universe. Option A would not provide any evidence for or against the astronomer's view. Option C may be problematic because a galaxy and a quasar may simply be at different distances and hence have different redshifts due to the Hubble expansion. Option D is irrelevant to this question. Option E may not be reliable since there could be other factors affecting the brightness of quasars.

An Astronomer Claims That the Large Redshifts of All Quasars