What does it mean by time slowing down at event horizon?
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The more gravity you are experiencing, the more that time slows down for you. Black holes have a lot of gravity so time would slow down a lot if you went near one.
The event horizon is the edge of a black hole.
Black holes exert gravity.
The move gravity in an area the slower time travels.
Technically this means if you could chill out next to a black hole for a few days you could come back to earth but it will be years ahead here.
It means as an outside observer watches you fall, they see each tick on your clock taking longer and longer to happen the closer and closer you get to this magical point
let’s imagine you’re hanging out near a black hole (but not in it).
one thing to keep in mind, you would not notice time slowing down. your time as far as you’re concerned would feel exactly like it is now. you’d look at your watch and it would tick at the same rate. you’d still be breathing, your heart pumping as normal. you’d hold normal conversations with the people next to you.
but, me, hanging out over here on earth, i could watch you through a telescope. and I’d see you moving in slow motion. your watch would tick more slowly than mine. your conversations would be lower in pitch and take longer. if you looked at me through a telescope, I’d be sped up. my watch would tick faster, my voice would be sped up like a cartoon character.
the closer you get to the event horizon the more extreme this effect. the most likely impact of this would be communications. in reality I’d never have a telescope that could view you. but you could flash a really bright light towards me, and communicate in morse code (or more likely a digital computer protocol). I’d see your flashes going very slowly. if i knew how fast you were flashing your light from your perspective, i could tell exactly how close to the horizon you were. weirdly, your light would get more and more red as well, for the same reason your voice would seem lower to me.
conversely, if i flashed a light at you, you’d see it flashing faster and more blue.
this effect is actually seen in our gps satellites. time goes slightly different for them (i think faster, as they’re not in our gravity well, but there’s other aspects that affect this too, like speed). so we need to account for the different clocks for gps to be accurate.
They always say relative to such and such a location. So I think it just means “appears to be going slow” just like a plane appears slow when it’s at 30,000 feet
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