Chapter 7

Stephen Hawking discusses how light and matter behave inside a black hole in this chapter. He reveals that both matter and light in a region at the cusp of a black hole neither fall into nor escape from the black hole. This leads to the idea that the area of a black hole's event horizon can be used to measure its entropy, which is a measure of disorder in an ordered system. However, this presents a problem because for something to have a temperature, it must emit energy and black holes are defined as not allowing energy to escape. Hawking resolves this problem by suggesting that virtual particles and their paired antiparticles can alter their properties and either fall into or leave the proximity of the black hole. This allows for the emission of energy from black holes, suggesting that their gravitational collapse is not an absolute certainty.