Because this is a very small region, rapid fluctuations could occur due to random fluctuations in the flow of matter into the black hole. In addition, we see different kinds of quasars, some with jets, some without, etc. These variations can be explained easily by the unified model. Different orientations of the accretion disk to our line of sight produce different types of quasars. When we view the quasar through its accretion disk, we see a different type of quasar than when we view it along the jet, exactly the same as for the closer, more familiar active galaxies discussed in this section.
Quasars are very distant objects.
The light we see from quasars has had to travel so far to reach us that it must have been emitted very soon after the beginning of the universe in order to arrive here today.