Black Holes Have a Lifespan, Too — and the Smaller Ones Burn Hot and Die Fast
Black holes look eternal, but physics says otherwise. Add mass and they get colder and live longer; shrink them down and they run hot, violent, and brief, ending in a burst of light. Even a sun-sized black hole would take roughly 10^67 years to fully evaporate — a span that makes the universe's 13.8-billion-year history look like nothing at all.