3 ms·
To an external observer, new material takes an infinite amount of time to cross the event horizon. So your intuition is kind of right there. But there is matter
by sp332 6y ago
To an external observer, new material takes an infinite amount of time to cross the event horizon. So your intuition is kind of right there. But there is matter that starts out inside the horizon, and there needs to be something going on in there because otherwise the gravity would keep pulling it tighter and tighter to infinite density in an infinitely small spot (the original meaning of "singularity").
- pdonis 6y ago> To an external observer, new material takes an infinite amount of time to cross the event horizon. While this is a common pop science statement, it is not correct. The correct statement is that the external observer never sees the material cross the event horizon, because, heuristically, it would take an infinite time for light emitted exactly on the event horizon to get out to the external observer. However, this does not equate to the external observer being able to assign an "infinite time" to the material crossing the horizon. The notion of "time" the external observer would have to use to do that is mathematically undefined on the horizon. > there is matter that starts out inside the horizon No, there isn't. When an ordinary object like a star collapses to a black hole, there is no horizon at all to start with, and there is no matter starting out inside any horizon.
- emerged 6y agoIt's that "keep pulling it tighter and tighter" that I'm wondering about. What if there's a separate force, or an aspect of gravity itself, which prevents a certain amount of gravitational density?