Mass bend space time, thats how we get gravity. A black hole has so much mass that it completely warps space time to the point where outward is not an available direction anymore.
Sometimes people visualize gravity using a rubber sheet and various balls. In this analogy a black hole would be a ball so heavy that it tears a hole into the sheet and if another ball then would fall into that hole it is off the sheet and can't get back on it.
random_edgelord t1_je9q22g wrote
Reply to ELI5: Why can black holes cause light to not escape, but light doesn't slow down from gravity(and only change direction)? by [deleted]
Mass bend space time, thats how we get gravity. A black hole has so much mass that it completely warps space time to the point where outward is not an available direction anymore.
Sometimes people visualize gravity using a rubber sheet and various balls. In this analogy a black hole would be a ball so heavy that it tears a hole into the sheet and if another ball then would fall into that hole it is off the sheet and can't get back on it.