The event horizon of a black hole looks like a final border, yet physics treats it more like a leaky interface. According to quantum field theory in curved spacetime, the vacuum near this boundary seethes with particle–antiparticle pairs that briefly emerge and annihilate.
When such a pair appears straddling the horizon, gravity can trap one partner while the other escapes as Hawking radiation. To an outside observer, that outgoing particle carries positive energy away, forcing the black hole to lose mass to keep energy conservation intact. The absorbed partner effectively has negative energy relative to distant space, shrinking the black hole’s mass and radius in small, cumulative steps.
This outward stream is thermal, with a temperature set by surface gravity at the horizon and closely tied to the black hole’s entropy. Smaller black holes radiate more intensely, accelerating their own demise as the process feeds on itself. Instead of permanent sinks of information, they behave like transient reservoirs whose stored mass–energy and entropy are gradually converted into radiation that disperses across the universe.
