According to quantum mechanics, everywhere, even supposedly empty space, has particles popping in and out of existence constantly. Every particle in the Universe also has an antiparticle, and if they meet both are annihilated. particle-antiparticle pairs constantly pop into existence, but immediately meet and disappear. Historically, scientists believed that nothing could escape from black holes. However, Stephen Hawking theorized that small quantum particles could actually escape due to what was later termed Hawking radiation. A black hole's event horizon is the line at which the gravitational pull of the black hole prevents anything from escaping. When a particle and antiparticle pair comes into existence right at the event horizon, the immense gravity sometimes pulls one antiparticle or particle in, but not the other. This prevents the two from annihilating each other and allows a particle to escape from the black hole. When the particle escapes from the black hole it takes some of the black hole's energy with it. Energy and mass can be converted between each other, so this escaped energy slightly decreases the mass of the black hole. Although the Hawking radiation process only occurs with very small particles and energy, on very long time scales it can lead to the evaporation of a black hole. If the black hole has nothing causing it to grow in mass, it will slowly lose mass due to Hawking radiation, becoming smaller and eventually dying out. This is believed to be the eventual fate of all black holes and occurs on immense timescales of trillions of years.
Hawking radiation is only theoretical. It has not been directly observed, and most likely never will be. The release of Hawking radiation deals in very small amounts of energy, while the area surrounding a black hole is generally extremely high in energy due to hot gas being pulled in. The Hawking radiation is much too hard to distinguish from the high energy processes normal at the event horizon, and therefore impossible to detect and prove. The theory of Hawking radiation combines the black hole mechanics of relativity with the particle theories of quantum mechanics. These two theories are not compatible and can rarely be made to fit together. The fact that two major theories do not work together demonstrates that one or both theories contain flaws, and are not representative of the true nature of the Universe. Because Hawking radiation is an unproven theory based on two likely flawed theories, it is doubtful that it is accurate.
[P1] Particles and antiparticles are constantly popping into existence, meeting, and annihilating each other. [P2] When a particle-antiparticle pair pops up near the event horizon of a black hole, one of the particles can be captured by gravity before they meet. [P3] This allows one particle to escape the black hole, subtracting energy and mass from the black hole. [P4] When a black hole stops growing, it will eventually die out due to this process.
Rejecting the premises
[Rejecting P2] This has not been experimentally proven, and is only theoretical.