How are some black holes’ event horizons bigger than others?

Question

If their mass is always contained in a singularity and their density is infinite, how are some black holes supermassive and others are not?

In: 5

Answer 1

The supermassive refers to the mass of the singularity. That singularity can be four solar masses or four million solar masses without any trouble.

The event horizons change because they’re based on the mass of that singularity. As you get closer and closer to the black hole, it becomes harder and harder to escape. The event horizon is where light can’t escape anymore and we can’t see what’s happening inside–the horizon beyond which we can’t see events in other words. Where that transition happens depends on the mass of the black hole just like the gravitational attraction of the Earth changes with how close you are to it.