3 ms·

>Also keep in mind that from the perspective of someone falling in, there's nothing particularly noticeable as you cross the event horizon. So I've heard that

by floxy 3y ago

>Also keep in mind that from the perspective of someone falling in, there's nothing particularly noticeable as you cross the event horizon. So I've heard that before, but let's say you are slowly spiraling into a supermassive black hole with very low tidal forces near the event horizon. You get close to the event horizon. Light can't escape. You stick your hand into / past the event horizon. Seems like a pretty definite discontinuity in "noticeability", if one second you can see your hand and move it around, and the next you can't see it and can't yank it back.

sliken 3y ago
Nothing anywhere close to event horizon can "slowly spiral in". There are no stable orbits within 1.5x the diameter of the event horizon. To get anywhere close without falling in would require a very powerful rocket, one that could accelerate to near light speed just to stay there. Now if you are falling in your hand never disappears, it's just that your body would accelerate into the black hole a little faster than your hand is accelerating because you are pulling back on your hand. But your hand never could have a negative velocity (moving away from the blackhole) no matter what you do.
naasking 3y ago
> You stick your hand into / past the event horizon. That wouldn't really happen. When people say that light cannot escape, they don't mean that a beam of light can't pass the horizon heading outwards, they mean that the curvature of spacetime is such that the photons will always curve back around and fall back into the hole. Locally, the horizon will look more or less the same to you, except at high curvature you'll start to see Doppler shift of light from outside vs. inside. At extreme curvature, an arm pointed towards the singularity will look red shifted and an arm pointed away from the singularity will look blue shifted. Although at this level of curvature, you'd already be ripped apart so you wouldn't really notice anything at all.

by floxy 3y ago

sliken 3y ago

Nothing anywhere close to event horizon can "slowly spiral in". There are no stable orbits within 1.5x the diameter of the event horizon. To get anywhere close without falling in would require a very powerful rocket, one that could accelerate to near light speed just to stay there. Now if you are falling in your hand never disappears, it's just that your body would accelerate into the black hole a little faster than your hand is accelerating because you are pulling back on your hand. But your hand never could have a negative velocity (moving away from the blackhole) no matter what you do.

naasking 3y ago

> You stick your hand into / past the event horizon. That wouldn't really happen. When people say that light cannot escape, they don't mean that a beam of light can't pass the horizon heading outwards, they mean that the curvature of spacetime is such that the photons will always curve back around and fall back into the hole. Locally, the horizon will look more or less the same to you, except at high curvature you'll start to see Doppler shift of light from outside vs. inside. At extreme curvature, an arm pointed towards the singularity will look red shifted and an arm pointed away from the singularity will look blue shifted. Although at this level of curvature, you'd already be ripped apart so you wouldn't really notice anything at all.