# What would happen if someone was sucked into a black hole?

Kutt
Hypothetically, what would happen if a person was sucked into a black hole? Would they just simply die?

## Answers and Replies

Homework Helper
Depends on the BH. A small one will rip you apart by tidal forces before you got close to the event horizon (the crossing of which I am guessing is what you mean by "sucked into").

A very big one may be OK - you'd just experience that you keep going - the view may get a bit strange. The event horizon is a coordinate singularity: exists in the math not real life.
http://www.jimhaldenwang.com/black_hole.htm

Kutt
Depends on the BH. A small one will rip you apart by tidal forces before you got close to the event horizon (the crossing of which I am guessing is what you mean by "sucked into").

A very big one may be OK - you'd just experience that you keep going - the view may get a bit strange. The event horizon is a coordinate singularity: exists in the math not real life.
http://www.jimhaldenwang.com/black_hole.htm

What would happen if Earth was consumed by a giant black hole?

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What would happen if Earth was consumed by a giant black hole?

We'd all be dead.

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A very big one may be OK - you'd just experience that you keep going - the view may get a bit strange. The event horizon is a coordinate singularity: exists in the math not real life.
http://www.jimhaldenwang.com/black_hole.htm

No, you'd still be sphagettified, it's just that it would happen inside the EH instead of outside the way it does on a small one.

Kutt
No, you'd still be sphagettified, it's just that it would happen inside the EH instead of outside the way it does on a small one.

Please explain what being "spaghettified" means.

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Tidal forces would stretch you into a thin string. It would be very unpleasant.

In holographic theory, black holes don't have an inside. If you cross the event horizon, you become part of the black hole, and you are somehow encoded onto the surface. It's speculative, though.

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In holographic theory, black holes don't have an inside. If you cross the event horizon, you become part of the black hole, and you are somehow encoded onto the surface. It's speculative, though.

I think "speculative" is an overly generous description of that theory, but that's opinion I know.

Kutt
The physics of black holes are absolutely baffling. Even top-notch astrophysicists have a hard time understanding them.

I don't think science has a solid and definitive answer of what black holes are and how they actually work. The only thing they have is theory and conjecture.

Homework Helper
See the link I provided in post #2 ... if the gradient across the event horizon is sufficiently shallow, we'd all just end up inside the event horizon. That would be a pretty big mass though.

"Insufficient" would mean you'd never make it to the event horizon.

When we are talking about general relativity effects we need to be careful though - particularly about who is doing the watching and where they are. We have to be careful to define out terms.

I have been guessing at the meanings of the terms of the question.
Don't make me guess.

Note: should this be in the science fiction forum?

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See the link I provided in post #2 ... if the gradient across the event horizon is sufficiently shallow, we'd all just end up inside the event horizon. That would be a pretty big mass though.

"Insufficient" would mean you'd never make it to the event horizon.

When we are talking about general relativity effects we need to be careful though - particularly about who is doing the watching and where they are. We have to be careful to define out terms.

I have been guessing at the meanings of the terms of the question.
Don't make me guess.

Note: should this be in the science fiction forum?

Why would you think this should be in SCIFIC? This is a straightforward discussion of BH's, like hundrends of similar threads here.

Kutt
If a black hole entered our solar system, would the sun and all of the planets be consumed?

Is it true that black holes drift aimlessly through the cosmos, or do they sit in a fixed position?

What creates black holes?

Do black holes ever close up and disappear, or do they exist forever?

What is known about supermassive black holes, such as the one in the center of our galaxy?

ApplePion
What would happen if someone was sucked into a black hole?

His insurance company would find a way of not paying.

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If a black hole entered our solar system, would the sun and all of the planets be consumed?

Is it true that black holes drift aimlessly through the cosmos, or do they sit in a fixed position?

What creates black holes?

Do black holes ever close up and disappear, or do they exist forever?

What is known about supermassive black holes, such as the one in the center of our galaxy?

I think you would be better off it you just Googled black holes and read up on them yourself, then come back here if you still have questions rather than just spouting questions at random about black holes.

Staff Emeritus
Hypothetically, what would happen if a person was sucked into a black hole? Would they just simply die?

I"d suggest reading Tedd Bunn's black hole FAQ. You might also try the sci.physics FAQ too.

http://cosmology.berkeley.edu/Education/BHfaq.html

I'll quote a longish section that seem relevant to your questions, in the hope you'll read the original.

What would happen to me if I fell into a black hole?
----------------------------------------------------
Let's suppose that you get into your spaceship and point it straight towards the million-solar-mass black hole in the center of our galaxy. (Actually, there's some debate about whether our galaxy contains a central black hole, but let's assume it does for the moment.) Starting from a long way away from the black hole, you just turn off your rockets and coast in. What happens?

At first, you don't feel any gravitational forces at all. Since you're in free fall, every part of your body and your spaceship is being pulled in the same way, and so you feel weightless. (This is exactly the same thing that happens to astronauts in Earth orbit: even though both astronauts and space shuttle are being pulled by the Earth's gravity, they don't feel any gravitational force because everything is being pulled in exactly the same way.) As you get closer and closer to the center of the hole, though, you start to feel "tidal" gravitational forces. Imagine that your feet are closer to the center than your head. The gravitational pull gets stronger as you get closer to the center of the hole, so your feet feel a stronger pull than your head does. As a result you feel "stretched." (This force is called a tidal force because it is exactly like the forces that cause tides on earth.) These tidal forces get more and more intense as you get closer to the center, and eventually they will rip you apart.

For a very large black hole like the one you're falling into, the tidal forces are not really noticeable until you get within about 600,000 kilometers of the center. Note that this is after you've crossed the horizon. If you were falling into a smaller black hole, say one that weighed as much as the Sun, tidal forces would start to make you quite uncomfortable when you were about 6000 kilometers away from the center, and you would have been torn apart by them long before you crossed the horizon. (That's why we decided to let you jump into a big black hole instead of a small one: we wanted you to survive at least until you got inside.)

What do you see as you are falling in? Surprisingly, you don't necessarily see anything particularly interesting. Images of faraway objects may be distorted in strange ways, since the black hole's gravity bends light, but that's about it. In particular, nothing special happens at the moment when you cross the horizon. Even after you've crossed the horizon, you can still see things on the outside: after all, the light from the things on the outside can still reach you. No one on the outside can see you, of course, since the light from you can't escape past the horizon.

How long does the whole process take? Well, of course, it depends on how far away you start from. Let's say you start at rest from a point whose distance from the singularity is ten times the black hole's radius. Then for a million-solar-mass black hole, it takes you about 8 minutes to reach the horizon. Once you've gotten that far, it takes you only another seven seconds to hit the singularity. By the way, this time scales with the size of the black hole, so if you'd jumped into a smaller black hole, your time of death would be that much sooner.

Once you've crossed the horizon, in your remaining seven seconds, you might panic and start to fire your rockets in a desperate attempt to avoid the singularity. Unfortunately, it's hopeless, since the singularity lies in your future, and there's no way to avoid your future. In fact, the harder you fire your rockets, the sooner you hit the singularity. It's best just to sit back and enjoy the ride.

Gold Member
If a black hole entered our solar system, would the sun and all of the planets be consumed?

Is it true that black holes drift aimlessly through the cosmos, or do they sit in a fixed position?

What creates black holes?

Do black holes ever close up and disappear, or do they exist forever?

What is known about supermassive black holes, such as the one in the center of our galaxy?

1) Unanswerable without further details.

2) "Fixed position" is not well defined without a context. Do you mean "fixed" with respect to the CMBR, or the galaxy in which it lives, or what? "Drift aimlessly" is also not well defined. Black holes move just like other stars since they interact gravitationally just like other stars.

3) Black holes may eventually evaporate due to Hawking radiation and so are not eternal; however, for a large black hole, this process takes an extremely long time (even on cosmological time scales).

4) We know some of its properties like its approximate mass and therefore the approximate event horizon size. We don't currently know very well how it formed; we only have a few suggested hypotheses.

Homework Helper
Why would you think this should be in SCIFIC? This is a straightforward discussion of BH's, like hundrends of similar threads here.
1. there was no Sci fi forum before.
2. OP is sprouting questions without seeming to be interested in discussion
3. At best, OP is in "idle speculation" mode

But since I posted that, there has been another question whose answer is basically the same as before ... there has been no attempt to use more precise terms, no indication that previous links have been used. Little indication that we've even been listened to.

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1. there was no Sci fi forum before.
2. OP is sprouting questions without seeming to be interested in discussion
3. At best, OP is in "idle speculation" mode

But since I posted that, there has been another question whose answer is basically the same as before ... there has been no attempt to use more precise terms, no indication that previous links have been used. Little indication that we've even been listened to.

+1 on all that

Kacela
It's my understanding that relative time slows down the nearer you get to the black hole - so the person in question would die of old age before reaching the black hole - if he ever does reach it. To an outside observer though, the "victim" getting "sucked in" would seem almost instantaneous.

Gold Member
It's my understanding that relative time slows down the nearer you get to the black hole - so the person in question would die of old age before reaching the black hole - if he ever does reach it. To an outside observer though, the "victim" getting "sucked in" would seem almost instantaneous.
That's completely the wrong way round. The outside observer would die of old age waiting for the other to fall in, but the person who falls in does so quite quickly from his or her own point of view.

d3mm
I"d suggest reading Tedd Bunn's black hole FAQ.
http://cosmology.berkeley.edu/Education/BHfaq.html

He writes in that FAQ

"Once you've crossed the horizon, in your remaining seven seconds, you might panic and start to fire your rockets in a desperate attempt to avoid the singularity. Unfortunately, it's hopeless, since the singularity lies in your future, and there's no way to avoid your future. In fact, the harder you fire your rockets, the sooner you hit the singularity. It's best just to sit back and enjoy the ride."

I assume he is basing this on the fact that if the proper time on two clocks is compared, the clock that shows the longest time is the one that is not not accelerated? However, would not the black hole victim experience time normally and thus would benefit from using the rocket engines in reverse?

Kutt
He writes in that FAQ

I assume he is basing this on the fact that if the proper time on two clocks is compared, the clock that shows the longest time is the one that is not not accelerated? However, would not the black hole victim experience time normally and thus would benefit from using the rocket engines in reverse?

Rocket engines would not be able to escape the gravitational pull of a black hole.

The gravity of black holes is so powerful, not even light can escape it.

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Rocket engines would not be able to escape the gravitational pull of a black hole.

The gravity of black holes is so powerful, not even light can escape it.

True, but utterly irrelevant to the discussion:

Once you've crossed the horizon, in your remaining seven seconds, you might panic and start to fire your rockets in a desperate attempt to avoid the singularity. Unfortunately, it's hopeless, since the singularity lies in your future, and there's no way to avoid your future. In fact, the harder you fire your rockets, the sooner you hit the singularity. It's best just to sit back and enjoy the ride.

Do you understand the question? Why is the bolded statement true?That's the question. What does your statement have to do with that?

d3mm
I have just read From Eternity to Here by Sean Carroll and he makes the same claim: using rocket engines would cause you to hit the singularity sooner.

Not understanding the physics of black holes I wonder if this is something to do with the shape of the gravity well causing all paths to lead "down" or if he is talking about what is seen from an observers POV?

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I have just read From Eternity to Here by Sean Carroll and he makes the same claim: using rocket engines would cause you to hit the singularity sooner.

Not understanding the physics of black holes I wonder if this is something to do with the shape of the gravity well causing all paths to lead "down" or if he is talking about what is seen from an observers POV?

I don't see how he could be talking about any observer other than the guys inside (one firing his rockets, one not) since no observer outside the EH is relevant.

I seem to recall hearing this before but I don't understand it.

Let's hope someone who DOES understand it joins the conversation and explains it.

d3mm
I think it is that your light cone is bent to point at the singularity, so there's no direction you can move in that results in you heading away. I too would like this confirmed or refuted.

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I think it is that your light cone is bent to point at the singularity, so there's no direction you can move in that results in you heading away. I too would like this confirmed or refuted.

Oh, I think that's definite, but it does not answer the question of why firing rockets gets you there sooner than not firing.

someGorilla
using rocket engines would cause you to hit the singularity sooner.

I guess this idea comes from the fact that free fall maximizes proper time. But it doesn't apply here! Free fall from A to B (points in spacetime) is the longest path between A and B, but if you fire your rockets you will land in C (elsewhere on the singularity).

This paper is interesting: http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.1029v1.pdf

Antiphon
I think it is that your light cone is bent to point at the singularity, so there's no direction you can move in that results in you heading away. I too would like this confirmed or refuted.

We'll never answer these questions until we send in a probe with a high-def camera and a scooper to retrieve core samples.

Yes, even light can't get out once you fall in; so we'll just lower half the probe through the event horizon then pull the data back up through ultrasonic waves on the tether.

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I guess this idea comes from the fact that free fall maximizes proper time. But it doesn't apply here! Free fall from A to B (points in spacetime) is the longest path between A and B, but if you fire your rockets you will land in C (elsewhere on the singularity).

This paper is interesting: http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.1029v1.pdf

Thanks for the reference. It completely contradicts the statement that we've been discussing and to me sounds MUCH more reasonable than that statement.

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We'll never answer these questions until we send in a probe with a high-def camera and a scooper to retrieve core samples.

Yes, even light can't get out once you fall in; so we'll just lower half the probe through the event horizon then pull the data back up through ultrasonic waves on the tether.

I can't tell whether your statement was tongue in cheek or unwitting nonsense. Care to comment?

willem2
Thanks for the reference. It completely contradicts the statement that we've been discussing and to me sounds MUCH more reasonable than that statement.

well, it doesn't completely contradict it. If you start from rest at the event horizon, freefall still gives the longest possible time, and any acceleration will make it worse.

Kutt
Some physicists have theorized that black holes are actually gateways to strange other dimensions, is there any evidence of that?

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Some physicists have theorized that black holes are actually gateways to strange other dimensions, is there any evidence of that?

So, I take it the article itself, which I did not read, must contradict the summary paragraph, which I did read, which says pointedly:

In general, the use of such rockets can increase your remaining time, but only up to a maximum value; this is at odds with the “more you struggle, the less time you have” statement that is sometimes discussed in relation to black holes.