Hawking radiation (S.W. Hawking; 1973): The theory which black holes emit radiation similar to any other hot body. The virtual particle-antiparticle pairs are continuously being made in supposedly empty space. Infrequently, a pair will be made just exterior to the event horizon of a black hole. There are three possibilities as:
• Both particles are imprisoned by the hole;
• Both particles flee the hole;
• One particle flees while another is captured.
The first two situations are straightforward; the virtual particle-antiparticle pair recombines and returns their energy back to the void through the uncertainty principle.
This is the third situation which interests us. In this situation, one of the particles has escaped (and is speeding away to the infinity), whereas the other has been imprisoned by the hole. The escape becomes real and can now be noticed by distant observers. However the captured particle is still virtual; since of this, it has to restore conservation of energy by conveying itself a negative mass-energy. As the hole has absorbed it, the hole loses mass and therefore appears to shrink. From a distance, it comes out as if the hole has released a particle and diminished in mass.
The rate of power emission is proportional to the inverse square of the holes mass; therefore, the smaller a hole gets the faster and faster it emits the Hawking radiation. It leads to a runaway procedure; what happens whenever the hole gets very tiny is not clear; quantum theory seems to point out that some kind of "remnant" may be left behind after the hole has emitted away all of its mass-energy.