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Most-Hawk-4175 t1_j27m7nq wrote

I think a PBS spacetime show talked about something like this. Of course the answer is ridiculously complicated but I seem to remember you would basically see everything frozen in spacetime including other observers in the black hole.

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kimthealan101 t1_j28kn82 wrote

So you don't die. You just stop

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Xentavious_Magnar t1_j28p6me wrote

Relative to people outside. Inside the event horizon, all world lines converge on the singularity, so you'll end up there eventually. How long that would subjectively take for the person inside is a fun question that I don't know the answer to.

Edit: also assuming people outside could see you, which they can't because any light bouncing off of you will also follow a world line into the singularity and never make it to them.

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gladfelter t1_j29b3gs wrote

Seems to me you couldn't think either since any conscious thought would require a round trip in your brain, and the party of the trip going away from the singularity wouldn't make it.

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Nerdcoreh t1_j2bfjjj wrote

In my understanding not YOU would stop but theTIME around you. So if you”fell” in a black hole you wouldnt notice the slowness of the time because that would be your normal (implying you are not dead by that time). Your brain functions would be just fine from your perspective

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wokeupatapicnic t1_j2br80d wrote

Mostly correct. You’d see the universe progressively move fast and faster towards infinite motion until the “light-death” of the universe. Again, that is provided you were able to perceive and maintain thought during the process. But yes, you would not feel like you were moving in slowmo or anything, but everything outside of the BH would begin happening faster and faster and faster as you blinked out of existence

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HouseOfZenith t1_j2bsewm wrote

That would be scary. When we develop space travel we should throw people in them.

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paloprint t1_j2c967q wrote

I’ve always said I’d volunteer. That’s one hell of a way ticket. But your name will be forever.

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big_black_doge t1_j2bd35l wrote

Time continues at its normal pace for all observers. What would happen is that you would not see the other person on the other side of the horizon ever again. They would both fall into the center after being spaghettified.

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undergroundsilver t1_j29cu7c wrote

I think you would die from the massive gravity pulling you to the center, probably flattened like a meat pancake

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beef-o-lipso t1_j28qeg9 wrote

No thought, no awareness?

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MoogProg t1_j28ugg5 wrote

Only spaghettification and a timeless orbit until the eventual accretion of your particles feeding the singularity removes your information from existence*

*That last part is being debated and some suggest information is not lost.

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[deleted] t1_j28zfyu wrote

I'm not studied enough to say much about it, but I believe some recent studies strongly suggest information is preserved. However that doesn't make much of a difference to the spaghettified spacefarer.

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spymaster1020 t1_j29part wrote

I've heard of this theory before,something about the information being spread out on the event horizon. But what about when black holes decay through hawking radiation? Does that carry away the information?

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lawblawg t1_j2angnj wrote

Yes, that’s the best solution we have. The information is encoded in quantum fluctuations in the shape of the event horizon, and Hawkins radiation is both caused by those fluctuations and carries that information away with it.

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33ff00 t1_j2ashy6 wrote

What type of information? What’s that mean here?

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MaelstromFL t1_j28v2y4 wrote

IF! You will more than likely be torn to shreds before you reach the horizon...

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lawblawg t1_j2anlfg wrote

It depends on the size of the black hole. For a supermassive black hole like Sagittarius A*, the average density is less than liquid water, and the tidal forces at the event horizon are negligible.

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kimthealan101 t1_j2b6m2i wrote

I just wanted to find an easy way to die. What is easier than just hanging out at an event horizon?

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capmap t1_j2bqex5 wrote

No. That's only from an outsiders' perspective.

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graveybrains t1_j2a5mwn wrote

Except the subjective experience of time never stops, no matter how dilated it gets, so the first thing you’d likely experience crossing the event horizon is the evaporation of the black hole, or the end of the universe, whatever those might look like.

If you could hang out for a while, you’d see the black hole growing around you as it’s gravity leaves space more and more distorted. The event horizon would be the point where the black hole wraps all the way around and closes behind you.

At that point there is no physical way out, and any direction you can travel is going to be inward.

…I may have seen too much PBS as a kid.

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WorstMedivhKR t1_j2amk4i wrote

You'd be spaghettified and die long before the evaporation of the black hole or hitting the singularity or the end of the universe.

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graveybrains t1_j2at6ky wrote

Depends. A black hole the size of Sagittarius A* probably wouldn’t spaghettify you, but I don’t remember why

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jaydfox t1_j2b665c wrote

If you double the mass of a black hole, its gravity doubles. But its radius also doubles. Gravity decreases with the square of the radius, so at double the radius, you have 1/4th the gravity. So double mass of the black hole, and you get 1/4th of double the gravity, or 1/2 the gravity at the event horizon. But the tidal forces that cause spaghettification decrease with the cube of the distance, so you get 1/2 the gravity and 1/4th the spaghettification. Make a black hole 10 times bigger, and you'll get 1/10th the gravity and 1/100th the spaghettification at the event horizon.

The black hole Sagittarius A* is about a million times more massive than a typical (stellar) black hole, so it's gravity at the event horizon is a million times smaller, and the spaghettification will be a trillion times smaller. Not sure if it's enough to survive being spaghettified near the event horizon, but a trillion times less stretching can't hurt. Black holes a thousand times more massive than Sagittarius A* exist in other galaxies, so they'd be even easier (a million times easier) to survive falling into. (Actually, there are a few known black holes about 10,000 times bigger or more than Sagittarius A*.)

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graveybrains t1_j2bkolq wrote

This guy is PBS!

Thank you 😁

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jaydfox t1_j2bqat6 wrote

Haha, no, but I do watch a fair amount or space channels (PBS Space Time, Dr. Becky, Anton Petrov, etc.).

One thing worth mentioning is that you'll eventually be spaghettified, no matter how big the black hole is. If a stellar mass black hole has an event horizon of about 3 km (I think, not positive), then a 1 million stellar mass black hole would have an event horizon of about 3 million km. But only when you get within 300 km of the singularity, would the tidal forces be as strong as at the event horizon of the stellar mass black hole. For the largest known black hole (66 billion solar masses, off the top of my head, but maybe there's a bigger one), the event horizon would be about 200 billion km in radius, about 2% of a light-year (so 0.04 light-years in diameter). But the tidal forces wouldn't be as strong as at the event horizon of a stellar mass black hole, until you were about 12,000 km from the singularity. This is due to the rapid decay of tidal forces with distance.

So in that sense, the person you were replying to was right. You will be spaghettified before you get anywhere near the hypothetical singularity, no matter how big. But with a big enough black hole, you'd get pretty deep into the black hole before you get ripped apart. Long enough to make interesting observations. Which is what the OP was asking about. What would you see if you fell into a large enough black hole? Long after you've crossed the event horizon, and long before you get close enough to the singularity to be ripped apart by tidal forces. I assume you would see stuff that fell in right after you, and stuff that fell in right before you. (If not, that implies you wouldn't even see your feet after they went in, if you went in feet first. And I seem to recall several different authors saying you would hardly notice yourself pass through the event horizon.) How much longer before and after? I assume the cosmic background radiation behind / above you would be blue shifted from microwave into infrared, visible, eventually ultraviolet, xrays, etc. Whether you get ripped apart before witnessing that, I don't know. I'd like to know.

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WorstMedivhKR t1_j2dsjjw wrote

You will eventually be spaghettified regardless. In a large enough black hole it's after you cross the event horizon but before hitting the singularity.

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Ryunah t1_j27r4kj wrote

Yeah, I remember that too. I definitely remember them mentioning something about being frozen once you crossed into the hole. That you wouldn't be able to move and that time would completely stop or something like that. You'd never make it to the other side.

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WorstMedivhKR t1_j2amc26 wrote

That's what it looks like to a distant external observer. Except even then the person gets redshifted to invisibility pretty quickly. If you're inside time still passes "normally" locally.

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fromadifferentplanet t1_j2az8xl wrote

There's a great episode of Star Talk Radio in its earlier years and they cover all this.

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Theometer1 t1_j2a7b6d wrote

Seen a video on it as well it said for the observer they would see you die but in your perspective you crossed into the black hole but can never leave it.

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Spaventoo t1_j2ayxn2 wrote

Is that because black holes are a localized end of the universe?

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