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incarnuim t1_j279p4c wrote

A very very very large black hole (1e999 solar masses - larger than the mass of the universe) would theoretically be large enough that crossing the event horizon would be unnoticeable. The singularity would be several thousand ly away from the EH, so there would be no sheer stresses or tidal forces to speak of.

And yet -- No, you could not dip a cable down across the EH and get any signal. Space and Time coordinates reverse on the other side of the EH, so cable or no cable, a signal can only travel "up the cable" by going backwards in time. Even if the signal could do that, your future self wouldn't be there to receive it, so you can't get any information that way.

You could, however, live a very nice life just inside the EH, on a nice little planet orbiting a sun like star in a quaint dwarf Galaxy spiraling into the singularity over the course of a billion years or so....

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piousflea84 t1_j27cnsq wrote

Yeah isn’t there something about how gravitational time dilation reaches infinity at the event horizon? Like going down to the black hole planet in “Interstellar” caused 20 years to elapse within minutes, because it was close to the event horizon.

Going down to the event horizon and coming back up would take an infinite amount of time, which no matter or information can possibly survive. So it does not matter what you do, you can’t get anything back.

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Technical_Scallion_2 t1_j27msge wrote

My understanding is that if the black hole is rotating, you can reach the event horizon. It’s only for nonrotating black holes that the time dilation causes everything to keep slowing down and never actually reach the horizon. I’m not a physicist but I was curious about this a while since it seemed like black holes could never grow bigger because nothing could ever get inside, but if they’re spinning they can absorb new matter (I think).

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Impossible_Pop620 OP t1_j27a1hh wrote

Right, thank you...everyone thought I was barmy. Now, what would happen in your scenario if you were to try to RETRACT said cable?

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B1tVect0r t1_j27bkhs wrote

You would pull up a cable with whatever probes or detectors you had attached to the end sheared off, with no data ever having been received from anything past the event horizon. Whatever signals you received as you approached the event horizon are also probably garbled beyond all comprehension; relativistic effects mean that for every second of time you experienced, the probe experienced orders of magnitude more. My guess would be that the data throughput on the cable would drop with the inverse square of the distance from the probe to the EH until it becomes functionally 0 (assuming you have a magical, radiation- and hot-matter-immune probe)

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Impossible_Pop620 OP t1_j27c30p wrote

But there would be no stresses acting on it at the event horizon...or only 'unnoticeable ones' ...

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B1tVect0r t1_j27c6ds wrote

What are you drawing that conclusion from?

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Impossible_Pop620 OP t1_j27ccyr wrote

Check out cardamoms Post above mine...he said crossing the event horizon (of a very large BH) would be unnoticeable

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B1tVect0r t1_j27d52v wrote

Imperceptible to the entity crossing the horizon emphatically does not mean that there are negligible or net zero forces acting on that entity.

If you had two hydrogen atoms separated by the width of the galaxy, they would still gravitationally influence each other.

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MethSiller- t1_j27jqan wrote

I’m a little new here but this piqued my interest. Can you give me a quick briefing on why they would influence each other at such a massive distance?

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B1tVect0r t1_j27k8fj wrote

Because that's how the math works. The equation that you use to determine gravitational force between two objects has the distance between them squared in the denominator, meaning that no matter how large you make it the value is never 0 (although it may be so infinitesimally small that for all intents and purposes it is nonexistent)

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MethSiller- t1_j27klzp wrote

Man… that’s interesting… and thought provoking. Thanks for taking the time to explain.

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Impossible_Pop620 OP t1_j27dmj6 wrote

That reply sounds like 'we don't know' what stresses might apply here

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Mike2220 t1_j27fdzd wrote

The effect of gravity on the object at the other end of the tether would be so strong you'd need an infinite amount of force to pull it out.

You're forgetting that the idea of the event horizon is that even light cannot escape as the effect of gravity is too strong.

If a massless photon does not have the energy to escape, then how could you ever accumulate enough to free something with mass.

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s1ngular1ty2 t1_j27dyhg wrote

Your entire line of posts shows you do not understand any of this stuff even remotely and are just spouting jargon you have heard from other people. People have explained it to you, you just don't understand it.

No tether can survive what you describe. You can't pull it back out because gravity is massively strong at the event horizon so you'd have to exert almost an infinite force to pull it back out which would rip the cable.

You are confusing someone floating across the event horizon with pulling something out because you lack the understanding of how forces work and how any of this works.

Floating across the event horizon is NOT THE SAME as pulling something back out.

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Impossible_Pop620 OP t1_j27e2qr wrote

Thanks man...you have mentioned this once or twice, I think. Dunno why you're still posting it, really...

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s1ngular1ty2 t1_j27edxw wrote

Because it's true and you are wrong...

LUL...

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rabbid_chaos t1_j27n4vy wrote

Honestly, judging from OPs replies, some of what he's asking would require a black hole to not behave like a black hole, which at that point it wouldn't be a black hole.

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angrymonkey t1_j27h362 wrote

> he said crossing the event horizon would be unnoticeable

...To a body that is in freefall.

A body that is suspended over the event horizon would be experiencing atom-crushing acceleration.

Compare to a familiar scenario: If you are freefalling towards the Earth, you can't tell apart your experience from one of floating in interstellar space (ignoring tides, which is what we neglect when we say the black hole is large). If you are standing on the surface of the earth, though, you are experiencing 9.8m/s^2.

Near the surface of the black hole, there would be so much acceleration required to counteract the gravity there that no material could possibly stay intact.

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ManInBilly t1_j27cih7 wrote

You would pull the cable, grab the camera, effortlessly. Just to realize right after that you pulled your self onto the event horizon in doing it so.

Or if you were on a spacecraft, keeping a stable orbit using thrusters, then the cable would rip apart as it would be dragged into the black hole.

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Impossible_Pop620 OP t1_j27ddv7 wrote

My original post specified another large, non-BH body in orbit

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ManInBilly t1_j27dsm8 wrote

Same as for the spacecraft with thrusters. Doesn't matter how you keep the stable orbit.

The cable would rip.

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PhunkyPhish t1_j27limc wrote

What if you used a theoretical unbreakable cable, and tied a camera onto the other end, tossing that one into a similarly sized blackhole a substantial distance (negligible gravitational effect otherwise) apart?

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rabbid_chaos t1_j27mpn9 wrote

If I'm correctly interpreting what you're asking, then the answer is that you would now have two black holes locked into rotation around each other. This will ultimately result in the two black holes falling into each other and you being deleted from existence. Literally gone, reduced to atoms.

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incarnuim t1_j27foba wrote

You'd come up empty handed. Yes, weird physics applies here, because, as I said in my original post, you are dealing with a 1e999 solar mass BH. And we are not asking what happens at those energies, we are just applying GR gravity the way God and Albert intended.

Your cable would be sheared, with no shear forces, because your probe is now in the past, or else it is still on the other side of the EH, But YOU are in the future of YOU.

It's a bit like the famous scene from Spaceballs. You are asking, "what happened to then?", And I'm telling you, "You missed it. It's now now. Everything that's happening now, is happening now."

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Impossible_Pop620 OP t1_j27fywj wrote

Time would shear it? As you pass the EH there's a significant change, then?

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MasterKaein t1_j27iagx wrote

Yeah because the effect of time would be dilated. Think about this. You are driving in a straight line but suddenly your leg gets dilated significantly into the past while the rest of you accelerates into the future.

What do you think will happen to your leg? There's no forces exerting on it because it's the same force, the motion of the car going forward. But yet if the leg was in the past and the rest of you in the future it would be as if it were sheared off because it wouldn't share the same momentum you share due to the shift in its own relative time.

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incarnuim t1_j2bqwv2 wrote

The probe wouldn't notice a significant change. In fact it would be really tough for the probe to pinpoint when or even IF it had actually crossed the EH.

But you wouldn't get the probe back, you wouldn't get any signals, and you wouldn't feel any significant change in forces. The probe would just be gone (from your PoV). Meanwhile the probe would think it was still attached and sending back data, but the data never gets there....

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