Time dilation is the phenomenon in which time slows down for an observer inside a fast-moving object. The idea of time dilation is not a new one. It was first proposed by Albert Einstein in his theory of relativity, and has been tested many times since then. The theory of relativity suggests that if you are traveling at the speed of light, your time would slow down relative to those who are stationary. In the context of black holes, the closer you get to the event horizon, the slower time moves relative to those outside it. This means that if you were to fall into a black hole, your watch would tick slower than if you were standing on Earth's surface. This is due to gravitational time dilation - a change in how fast time passes as one approaches an object with gravity.

Quasars are the most luminous objects in the universe. They are powered by supermassive black holes that can be billions of times more massive than our sun. The first quasar was discovered in 1963 by a graduate student, Maarten Schmidt, at Cal Tech. Quasars are a type of active galactic nuclei that emits strong electromagnetic waves. They are also called quasi-stellar objects or QSOs. Quasars can be used to find black holes because they are very close to them, and as a result, they move around them in a process called gravitational lensing.

Black holes are objects that have gravitational fields so strong that nothing, not even light, can escape from them. They are often found at the center of galaxies and are the most massive objects in space. The term "black hole" was coined by physicist John Wheeler in 1967. Black holes come in many different shapes and sizes. They range in size from small black holes with the mass of a car to supermassive black holes with the mass of millions of suns. In astronomy, they are often called "stellar mass black holes" or "primordial black holes." A stellar mass black hole forms when a star dies and collapses under its own weight. It is typically the size of the Earth, but can grow to be as large as 20 times the size of our sun. The primordial black holes are believed to be the seeds of all the galaxies in the universe. They were formed when the universe was only a few hundred million years old and started with a tiny size.