Instead of a gentle bump in space-time, a black hole is so compact that it punches a hole in the fabric of space-time.

Think about this. The strong force is 1044 times stronger than gravity, yet given enough mass, gravity wins in the end. Wimpy gravity turns out to be the ultimate mouse that roared.

So what happens inside a black hole? We don't have a clue. Since there is nothing to stop the squeeze of gravity, all matter in the core is squeezed smaller and smaller until the diameter shrinks to zero.