Black holes are not eternal and will eventually evaporate.

In 1974, theoretical physicist Stephen Hawking published a groundbreaking paper in the journal Nature titled 'Black Hole Explosions?'. He proposed that quantum effects near the event horizon allow black holes to emit thermal radiation. This occurs because vacuum fluctuations constantly create pairs of virtual particles and antiparticles. Normally, these pairs instantly annihilate each other and disappear.However, if a pair forms exactly at the event horizon, one particle may fall into the black hole while the other escapes into space. To conserve total energy, the particle that falls in must have negative energy from the perspective of an outside observer. This reduces the black hole's mass by a tiny amount. This phenomenon, now known as Hawking radiation, implies that black holes have a finite lifespan and a specific temperature.The rate of evaporation depends on the black hole's mass. Smaller black holes radiate more intensely and disappear faster, while massive ones take much longer. For a black hole with the mass of our Sun, the evaporation process would take approximately 10 to the power of 67 years. Supermassive black holes at the centers of galaxies could take up to 10 to the power of 100 years to fully evaporate. This discovery bridged the gap between general relativity and quantum mechanics.