Recently, March 14, 2018, Stephen Hawking’s name has become more resonant than ever before. The news of the death of the most famous physicist after Albert Einstein is filled the virtual world, drove across the vast ocean, to our country Indonesia. Stephen Hawking rested forever at the age of 76.
Stephen Hawking is often dubbed the smartest living human being. There is little pride in our minds because it is lucky to be able to live as a great scientist. But now that sense of pride has gone, along with the last breath that blows from this physicist.
One of Stephen Hawking’s great contributions to physics is his theory of black holes . Black hole is a very massive object so no one can escape from the pull of gravity.
Initially black holes are only considered as mathematical objects born of the general theory of relativity only. But now we know that the black hole really exists in the real world. 
What is Stephen Hawking’s contribution to the theory of black holes? Consider the following explanation.
The Stained Space Is Not Really Hampa
Our reasoning is shaped by experience. At first we thought that heavy objects fall faster than light objects. This is because in everyday life we do see it that way. But after we look more closely it does not. Heavy objects and light objects fall together when air resistance is removed. This is the reason why the theory of relativity and quantum theory is difficult to digest by reason. In everyday life we have never dealt with super-fast objects or super-small objects. That’s why we should not be too confident with our common sense .
The law of conservation of energy is a very logical law, in accordance with our daily reason. It is impossible for matter to appear suddenly from the void. But it turns out two plus two is not always equal to four. Quantum theory has modified the law of conservation of energy through a principle whose name is Heisenberg’s uncertainty. Material may suddenly emerge from the absence provided that it vanishes immediately. The consequence of this is very spectacular. Heisenberg’s uncertainty principle gives us a new understanding of what voidness is.
What comes to mind when we hear the word “hollow”? Our reason describes emptiness as emptiness, nothingness, dark black, without anything there. But it turns out that quantum theory says something else. The vacuum is not really empty. The vacuum was full of activity. Couple particles and anti-particles suddenly appear then meet again and mutually eliminate. Appears to disappear, reappear, disappear again, and so on. According to quantum theory, vacuum is a very crowded place.  This quantum theory is used by Hawking to describe black holes.
Theory of General Relativity vs. Quantum Theory
Today almost everything that exists in the heavens and on earth can be explained by two major theories of physics, the theory of general relativity and quantum theory. The general theory of relativity is able to explain massive objects such as stars, galaxies, and the universe. Meanwhile, quantum theory is able to explain small objects such as atoms, protons, and electrons.
Normally large mass objects must be large in size so we do not need to review them with these two theories at once. But there are two places where small objects have a very large mass at the center of the black hole and at the beginning of the universe.
To find out what happens at the center of the black hole as well as at the beginning of the universe, we need to unite the general theory of relativity with quantum theory. This theory of unification is the dream of Stephen Hawking, Theory of Everything .
But it turns out to unite the two (the theory of general relativity and quantum theory) is not easy. Until now we still do not have Theory of Everything so we still can not analyze what happened at the center of the black hole and at the beginning of the universe.
Stephen Hawking has not been able to figure out what’s going on in the center of a black hole because he has not succeeded in composing Theory of Everything . But he has made the first step to get there. Before approaching the center of the black hole, it is better to grope the surface first.
Researching the surface of a black hole does not need to use Theory of everything in its actual version because the gravity there is not as strong as gravity at the center of the black hole. Simply use quantum theory but in a curved spacetime background . 
What happens when Stephen Hawking sees the surface of a black hole using quantum theory? This is where the revolution takes place. Hawking sees a pair of particles and anti-particles that appear on the horizon of a black hole. Black hole has a horizon or a safe distance. Any object that includes light when it has crossed the horizon will not get out again. That’s why the black hole is black, because no light can come out of it.
Some of the particle and anti-particle pairs that appear on this horizon will not be able to meet again to cancel each other out. As a result, one particle enters the black hole and the other is released as radiation. Particles that enter the black hole have a negative mass that will reduce the mass of black holes.
From the outside, black holes appear to shrink while emitting radiation. Radiation is then known by the name of Hawking Radiation . It is a revolution because the former black hole is known as an object that does not want to remove anything that has been swallowed. But Hawking said that the black hole turned out to emit radiation alias “shine”. 
 Science Channel. 2014. Through the wormhole – The riddle of black hole . https://www.youtube.com/watch?v=K8QfYWKoTDA accessed March 14, 2018
 Krauss, Lawrence. 2012. A Universe from Nothing . USA: Free Press
 Carroll, S. (2004). Spacetime and Geometry, An Introduction to General Relativity Chicago: Addison Wesley
 Muon Ray. 2015. Stephen Hawking Lecture – How to Escape Out of a Black Hole. https://www.youtube.com/watch?v=h_d7O9JGo_s accessed March 14, 2018