The rotation curves of galaxies show that the stars in the outer regions of galaxies are moving faster than expected based on the visible mass of the galaxy. This suggests that there is a large amount of unseen mass, or dark matter, that is responsible for the extra gravity.

The accelerating expansion of the universe is the primary evidence for the existence of dark energy. This expansion is causing the distance between galaxies to increase at an ever-increasing rate, and it cannot be explained by the known forms of matter and energy.

Dark matter plays a role in all of the stages of the formation and growth of supermassive black holes. It helps to form the seed black holes that eventually grow into supermassive black holes, it provides the gas that fuels the growth of supermassive black holes, and it helps to stabilize the accretion disks around supermassive black holes.

Dark energy is causing the universe to expand at an ever-increasing rate. This expansion is causing the galaxies to move away from each other, which makes it more difficult for supermassive black holes to form.

Supermassive black holes are expected to eventually evaporate due to Hawking radiation. This is a process by which black holes emit particles and energy, which causes them to lose mass and eventually disappear.