Quasars and the Big Bang

The abundance plot for quasars versus time shown in the left panel is a strong argument that the Universe changes over time. This is consistent with the theory that the Universe started from a big bang, but is not consistent with a rival theory, the steady state hypothesis, that competed with the big bang theory at the time that quasars were discovered.

This was one of the reasons that the steady state theory was finally rejected in favor of the big bang theory. We shall discuss the big bang and steady state theories in Chapter 27.