Eddington–Finkelstein coordinates

Eddington–Finkelstein coordinates are a way to describe black holes that remove the tricky "singularity" problem at the event horizon—the point where nothing can escape. Unlike traditional coordinates, which become problematic near the horizon, these coordinates smoothly represent the spacetime, allowing us to see how objects and light behave as they approach or cross the black hole. Essentially, they provide a clearer, more complete picture of the black hole’s surroundings, highlighting that nothing physically prevents entry into the black hole, just that certain coordinate systems don’t handle the horizon well.