A friend of yours who is a science fiction fan hears you talk about the fact that astronomers now believe that the mechanism for the large energy output of quasars involves a supermassive black hole. He challenges you, saying something like "Oh come on, every science fiction fan knows that nothing, not even light, can escape from a black hole! How can a black hole be an energy source?" How would you respond to his objection?

the energy we see from quasars comes from regions where matter is falling in, these regions are still outside the event horizon

Explanation:

Quasar is an extremely luminous active galactic nucleus (AGN), in which a supermassive black hole with mass ranging from millions to billions of times the mass of the Sun is surrounded by a gaseous accretion disk. They are formed when material falls into the accretion disc around a supermassive black hole at the centre of a galaxy. quasar is a massive sources of Energy. This massive energy source produces visible light and emit more X-rays than any known source. If we assume that this energy emitted by quasars is also produced by a hot accretion disk, then, the size of the disk must be given by the time the quasar energy takes to vary. For quasars, the emission in visible light varies on typical time scales of 5 to 2000 days, limiting the size of the disk to that many light-days.

temp rises, and expansion