Black Hole Shenanighans

[Duxwing]

Black holes' enormous gravity can be exploited for fun and profit: post and debate your shenanighans below!

Abyssal Bungee Jump

Suppose you flew a massive spacecraft near the event horizon of a black hole, tied a bungee cord around your space-suited waist, and and leapt in. Would you live to tell the tale?

I argue that you would and that the implications could be useful. You would live because black hole gravity is classical and therefore reducible to point masses. The first point mass would represent the black hole; the second, the system of your craft and you. This second point mass would move negligibly during your jump and therefore not cross the horizon, enabling your return.

The implications of your imaginary survival could be useful. One therefore could lower probes into black holes however-far your tether would let you, determining what lies beyond the event horizon and perhaps seeing a singularity.

Heavenly Mass Driver

Suppose you instead flew your spaceship just inside the event horizon and let her fall inward until tidal forces nearly ripped her apart, finally Alcubierre-jumping home. What would happen?

I argue your homecoming ship would be traveling such a large fraction of c that you could safely orbit the black hole. Successive trips, perhaps deflected from the black hole's center of mass, would further increase your velocity until you neared light speed without expending onboard energy.

Humanity thereby could 'ride-out' galactic problems by riding just outside the event horizon, watching the universe whip past in full-color gamma-ray. Upon leaving warp by the opposite method--pointing the velocity vector athwart gravity--we could even ignite stars by coliding at relativistic velocities tanks of hydrogen put into gas clouds.

-Duxwing

[Scotius]

The closer you are to the black hole, time moves slower for you. You could bungee-jump near the event horizon, return to your ship...and find that the crew died of boredom decades ago

Alcubierre Drive is supposed to warp spacetime around itself. Black hole does it already - at much, much bigger scale. I imagine trying to engage warp drive near the even horizon would be like trying to swim up Niagara Falls.

[K^2]

You would live because black hole gravity is classical and therefore reducible to point masses.

Where'd you hear that nonsense? It's completely wrong.

[Secuas]

You would be teared apart ;P

[AngelLestat]

even if you drop a camera with a wire, you will not be able to sent any signal from the camera to your ship.

There is no way that we know, to measure how a black hole looks inside. The event horizon is the limit between this universe and something else.

[Albert VDS]

The event horizon is the limit between this universe and something else.

No matter whats inside a black hole, it is still in this universe.

All the speculations of it being a wormhole, and what not, is just that.

[Bill Phil]

Seeing a singularity is kind of impossible, seeing as they don't reflect light back...

[cicatrix]

Yup, this question has been bothering me for a long time. Imagine I orbit a black hole several millimeters above the event horizon (let's say I know exactly where it is and always manage keep my craft at that distance). Then I go EVA and use a long pole to stick it below the event horizon. Would I be able to pull it back?

[michaelsteele3]

Black Hole Shenanigans

Shenanigans

...

[AngelLestat]

No matter whats inside a black hole, it is still in this universe.

All the speculations of it being a wormhole, and what not, is just that.

If you accomplish to pass that line, it means that our universe ends due time dilation.

So yes, that is the limit of our universe.

Yup, this question has been bothering me for a long time. Imagine I orbit a black hole several millimeters above the event horizon (let's say I know exactly where it is and always manage keep my craft at that distance). Then I go EVA and use a long pole to stick it below the event horizon. Would I be able to pull it back?

Not, is easy, nothing that moves slower than light can escape. So nothing. And there is other implecations in time-space distortion.

Edited February 12, 2015 by AngelLestat

[Duxwing]

Where'd you hear that nonsense? It's completely wrong.

My statement was rough and meant that at large scales, far from the roiling mass of doom comprising the singulairty, Keplerian mechanics adequately simulate the motion of bodies orbiting a black hole; the event horizon is simply the orbit at which orbital velocity equals c.

My speculation about orbiting the black hole and lowering yourself below the horizon was intended to illustrate an interesting and perhaps-useful implication of this simulation: parts of a body whose center of mass is above the event horizon can cross it and return.

-Duxwing

[rtxoff]

Anyone watched "The Black Hole (1779)" ?

I liked that movie as a kid.

[Albert VDS]

Yup, this question has been bothering me for a long time. Imagine I orbit a black hole several millimeters above the event horizon (let's say I know exactly where it is and always manage keep my craft at that distance). Then I go EVA and use a long pole to stick it below the event horizon. Would I be able to pull it back?

Seeing as gravity increases like a gradient, you wouldn't even be able to move the stick around.

It would also be ripped apart.

If you accomplish to pass that line, it means that our universe ends due time dilation.

So yes, that is the limit of our universe.

Our universe does not equal time.

If it isn't part of our universe then it wouldn't be able to interact with it.

[Duxwing]

Seeing as gravity increases like a gradient, you wouldn't even be able to move the stick around.

It would also be ripped apart.

Our universe does not equal time.

If it isn't part of our universe then it wouldn't be able to interact with it.

Around a supermassive black hole, the tidal forces would not be unbearable near the event horizon.

-Duxwing

[PakledHostage]

Anyone watched "The Black Hole (1779)" ?

I liked that movie as a kid.

Erm? Did they have movies in 1779? And how is it that you aren't, er, "pining for the fjords" by now?

[cicatrix]

Not, is easy, nothing that moves slower than light can escape. So nothing. And there is other implecations in time-space distortion.

So, what would happen if I pulled the pole? I will pull eternally?

[-Velocity-]

Around a supermassive black hole, the tidal forces would not be unbearable near the event horizon.

-Duxwing

Correct. Also, tidal forces are not a fundamental physical limit, so they cannot be what prevents you from pulling back the rod.

The question raised is a good one. Remember, NOTHING can escape the event horizon. So what even keeps the rod holding itself together? If it's a rod made out of the kind of matter we're familiar with, it's held together by electromagnetic forces, which exert themselves through the exchange of photons- virtual or real. So the very forces that hold the rod together couldn't communicate across the event horizon. Yet, we're told that an infalling observer notices nothing unusual as he crosses the event horizon, especially the event horizon of a supermassive black hole. He doesn't fly apart as he crosses the event horizon. He also supposedly doesn't cross the event horizon in finite time from the point of view of the external universe. At the SAME time, we're told that black holes can gain mass, which isn't possible if nothing ever crosses the event horizon!!!

I once read that infalling material is added to a black hole in finite time because as it approaches the event horizon, the event horizon expands to meet it- because the added infalling mass has its own gravity that creates a new, slightly larger event horizon. This is at odds with the many statements I've read about how infalling matter never crosses the event horizon of a black hole.

Yea, I don't get it.

[Duxwing]

Correct. Also, tidal forces are not a fundamental physical limit, so they cannot be what prevents you from pulling back the rod.

The question raised is a good one. Remember, NOTHING can escape the event horizon. So what even keeps the rod holding itself together? If it's a rod made out of the kind of matter we're familiar with, it's held together by electromagnetic forces, which exert themselves through the exchange of photons- virtual or real. So the very forces that hold the rod together couldn't communicate across the event horizon. Yet, we're told that an infalling observer notices nothing unusual as he crosses the event horizon, especially the event horizon of a supermassive black hole. He doesn't fly apart as he crosses the event horizon. He also supposedly doesn't cross the event horizon in finite time from the point of view of the external universe. At the SAME time, we're told that black holes can gain mass, which isn't possible if nothing ever crosses the event horizon!!!

I once read that infalling material is added to a black hole in finite time because as it approaches the event horizon, the event horizon expands to meet it- because the added infalling mass has its own gravity that creates a new, slightly larger event horizon. This is at odds with the many statements I've read about how infalling matter never crosses the event horizon of a black hole.

Yea, I don't get it.

I think we're mixing physical properties with their metaphors. The statements 'nothing can escape a black hole' or that the 'event horizon blocks all information' is a metaphor--a rough statement like "black hole gravity is classical"--are metaphors meaning orbital velocity equals c near black holes and exceeds it nearer them. We can infer several truths from this property. We first infer that one cannot orbit a black hole below its event horizon, for orbital velocity there is superluminal and therefore-unattainable. We can infer next that one could not even radio messages home because one's radio waves also would be on sub-orbital trajectories. Hence the romantic notions of a mute, helpless fall into a great, terrifying unknown.

But I am no romantic: I wanted to return from and communicate through the event horizon. My learning limited to rudimentary Keplerian mechanics, I imagined the black hole were a point mass and my craft a rigid body. I therefore imagined that the craft would spiral inward only once its center-of-mass were suborbital and that the craft therefore could, keeping its center-of-mass in orbit, extend a retractable probe through the event horizon and thereby learn what lay beyond it. I started this thread because I wanted to know whether physical law permitted this seeming violation--which I called a black hole shenanigan.

-Duxwing

[AngelLestat]

Our universe does not equal time.

If it isn't part of our universe then it wouldn't be able to interact with it.

Our universe is space and time.

You can see the edge from distance, but if you get more close the universe ends and you go to some other place (or at least your energy)

So, what would happen if I pulled the pole? I will pull eternally?

No, because you have similar time distortion than your pole, it depends on the size of the black hole.

1) very tiny, your pole would break

2) medium size, you break too.

3) very big, both falls into the black hole.

[Brotoro]

Abyssal Bungee Jump

Suppose you flew a massive spacecraft near the event horizon of a black hole, tied a bungee cord around your space-suited waist, and and leapt in. Would you live to tell the tale?

I argue that you would...

Before you attempt this, please let us know where we can send flowers to express our condolences to your family.

[cicatrix]

I think I figured out what would happen to the stick I poke 'through' the event horizon. In this thought experiment I didn't think of the time. I won't be pulling the stick out forever, actually, from my point of view I will be poking it in forever since the closer the tip of the stick to the event horizon, the slower would be its 'local' time as compared to mine, so I won't live long enough to see the tip actually passing through. As I push the rod forward actually I pass the deformation wave across it towards the tip and this wave will propagate forever (for me) to reach the end.

Actually, I think I would see the stick contracting as I push it forward with its tip not moving at all.

[Sirrobert]

Wouldn't spagetification rip the stick apart? Or is that only deeper in the gravity well?

As I understand it, that close to a black hole gravity doesn't actually act as a point mass, but each part of the ship/you/stick that's closer to the black hole would suffer more gravity (as it's a gradient)

[Carl Sagan The S Stallion]

Suppose you flew a massive spacecraft near the event horizon of a black hole, tied a bungee cord around your space-suited waist, and and leapt in. Would you live to tell the tale?

Not really, if you bungee jumped past the event horizon or stuck a pole in, your ship would be sucked in too, since it is a part of your ship at that time. As stated above, you wouldn't even be capable of seeing beyond the event horizon. You wouldn't even be capable of getting out anyhow, seeing how you would have to travel faster than the speed of light to escape the event horizon.

The event horizon is the limit between this universe and something else.

Just passing the event horizon would not lead you into another place entirely. Realize that the event horizon is only the point in which light does not escape. It's much like the edge of a shadow, where just beyond is not necessarily something "different". That would be far beyond this point, down into the steepest part of the singularity, or even at the base, where, if you were lucky (or unlucky) enough to survive the trip, you would see, possibly, a swirling ball of matter, created by the matter collected from the area around you.

COUNTER QUESTION:

What I wonder is, "Could the singularity 'convert' matter into energy and emit it from the black hole as radiation?" We already know that black holes emit incredible amounts of energy in jets at the poles, so was that, at one point, matter? Could the matter and energy in the black hole be emitted from the poles and "take" from the black hole to achieve escape velocity (and is this causing black holes to evaporate?)? Could this escaping light be traveling faster than the cosmic speed limit to do so?

Take all this conjecture with a grain of salt, I'm only a high-school junior with an extreme interest in science. I haven't even taken high school physics (I traded it out for AP Chemistry)

[Sirrobert]

COUNTER QUESTION:

What I wonder is, "Could the singularity 'convert' matter into energy and emit it from the black hole as radiation?" We already know that black holes emit incredible amounts of energy in jets at the poles, so was that, at one point, matter? Could the matter and energy in the black hole be emitted from the poles and "take" from the black hole to achieve escape velocity (and is this causing black holes to evaporate?)? Could this escaping light be traveling faster than the cosmic speed limit to do so?

Take all this conjecture with a grain of salt, I'm only a high-school junior with an extreme interest in science. I haven't even taken high school physics (I traded it out for AP Chemistry)

No. I believe that the energy transmitted out of the poles is from matter swirling at the event horizon itself, not beond it

[kStrout]

There is a thought experiment that goes like this... There is a man in the middle of a moving train car with a lighter. There are two men, one on each end of the train car equal distance from the man in the center. When he lights the lighter, the light from the train travels at the speed of light and hits both men simultaneously. It doesn't matter that the train is moving, whenever you measure the speed of light it is traveling exactly at C to the reference frame of you. Now the train is passing a platform, and there is someone else watching this happen, they see the lighter being lit, but because the train is moving forwards relative to them, the light hits the man in the back first, and then the man in the front. So two events happened simultaneously in one reference frame, and at different times in another. Now let's apply this to black holes, we can observe material passing through the event horizon, but for the material, time slows down as it approaches the event horizon, and it never makes it there because at the event horizon time has stopped. To travel through the event horizon, time would have to run backwards, which would mean that the action of entering the event horizon would be undone.