None - they're valid inside the event horizon as well as outside. They are singular at the event horizon (##g_{tt}## is zero and ##g_{rr}## goes to infinity) so aren't valid there.Afonso Campos said:Which aspect of the metric in Schwarzschild coordinates indicates that the coordinates are only valid outside the event horizon?
Schwarzschild coordinates are a coordinate system used to describe the space-time around a non-rotating, spherically symmetric mass. They were first introduced by the German physicist Karl Schwarzschild in 1916 in his solution to Einstein's field equations of general relativity.
The event horizon is the boundary around a black hole beyond which nothing, including light, can escape. It is the point of no return for anything that gets too close to the black hole, as the gravitational pull becomes too strong for even light to escape.
No, Schwarzschild coordinates break down beyond the event horizon as they become singular. This means that they cannot accurately describe the space-time within the event horizon. Alternative coordinate systems, such as Kruskal-Szekeres coordinates, are used to describe the space-time within the event horizon.
Inside the event horizon, time becomes a spatial dimension. This means that objects inside the event horizon move towards the singularity (the center of the black hole) in the same way that objects move through space, rather than experiencing the progression of time as we do outside the event horizon.
No, once an object crosses the event horizon, it is impossible for it to escape. The gravitational pull is too strong for anything, including light, to overcome. This is why the event horizon is often referred to as the "point of no return."