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Is the Event Horizon of a Black Hole Equivalent to its Gravitational Boundary?

-- Heraldo Henrique Felix de Moraes | March 18, 2021

Question:

I was thinking about black holes a few days ago and I thought: wouldn’t the event horizon be equivalent to the boundary of a black hole’s gravitational field? Since it is known, for the time being, that the entire mass of a BH is concentrated in the singularity in the center at an infinite density, and the event horizon would be just a limit in space (and not a surface like themes on Earth or the Sun, for example), that is, just a theoretical boundary around a black hole from which the force of gravity is so strong that nothing, not even light, can escape. And, if it is known that only very close to the event horizon that stars or other objects in the vacuum of space are sucked into BH, just like a meteorite that passes very close to Earth, it would also be “sucked” into our planet due to interaction with our gravitational field. Am I right in my line of reasoning or am I thinking the wrong way?

-- Heraldo Henrique Felix de Moraes

Answer:

The event horizon of a black hole is a special kind of gravitational field boundary in that it represents the point within which information, in the form of electromagnetic radiation, or light, cannot escape the gravitational field of the black hole. In this sense it is much more than just *the* boundary of a black hole’s gravitational field, but a very special boundary within the black hole’s gravitational field.

-- Jeff Mangum

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