Spacetime

The event horizon is the boundary around a black hole beyond which nothing, not even light, can escape. It marks the point of no return, a critical concept in general relativity.

Rather than empty spaces, black holes are regions in spacetime where gravity is so intense that nothing, not even light, can escape. They form from the remnants of massive stars that collapse under their own gravity, creating a singularity.

According to Einstein's theory of general relativity, gravity causes time to slow down. Since there's slightly less gravitational pull at higher altitudes, time literally ticks faster compared to sea level, a measurable effect of spacetime curvature.