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In astronomy class, we have to state how gravity work in the black hole? I know for one fact is that black hole is strong enough to stretch you thin enough like a noodle. Any ideas?

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  • $\begingroup$ That question will win the Nobel Prize one day. And this is your homework? It is a tough class you're taking. Do let us know what the key says about it! $\endgroup$ – LocalFluff Oct 29 '15 at 13:26
  • $\begingroup$ Yes, is it sort of my assignment! But I have investigate in my notebook, it says something about light can't even escape! $\endgroup$ – Needtolearnmore Oct 29 '15 at 14:09
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    $\begingroup$ I don't think this question shows even a minimal good-faith research effort. If you have a specific question, such as needing clarification on some aspect of black holes, please edit. $\endgroup$ – Stan Liou Oct 29 '15 at 14:54
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    $\begingroup$ @user307592 read over your course material and think about what it says, then come back with a specific question. Other wise you are just saying "I do not want to learn this, I just want to be told an answer." $\endgroup$ – Eubie Drew Oct 29 '15 at 17:52
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    $\begingroup$ I'm voting to close this question as off-topic because of lack of research effort. $\endgroup$ – HDE 226868 Oct 30 '15 at 21:49
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Gravity works exactly the same around a black hole as it does everywhere else in the universe:

The mass of the black hole distorts spacetime, and then objects follow the shortest route in the curved spacetime. The only difference between the gravity of a black-hole and the gravity of Earth is that the Black hole has a much larger mass in a much smaller volume, so the gravitational field is much stronger.

The strength of gravity has several consequences I'll mention three:

First close to the black hole spacetime is so curved that light can't escape. Now all gravity bends light a bit, but you usually don't notice it. A black hole bends light a lot. The edge of the black hole is called an event horizon and it is the closest distance that light can go to a black hole and not fall in. Nothing can ever pass from within the event horizon.

Next there are tidal forces. All gravity can cause tides: the force of the earth gravity is a bit more on your feet than on your head. Usually you don't notice. However a solar mass black hole has such extreme tides that you would be pulled apart by the difference in force (this is the spaghettification you mention)

Finally, inside the black hole, space works like time. You can't change your direction in time (unless you have a Delorean) Inside a black hole you can't change direction in space.

But remember the only difference between the gravity around a black hole and the Earth is a matter of degree.

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  • $\begingroup$ By gravity I am implicitly meaning "gravity as modelled in GR". The question asks about gravity both "in" a black hole (I assume this means within the event horizon) and around it, as "stretch...like a noodle" occurs outside the event horizon. The basic assertion: gravity is the same inside and outside a black hole I stand by. Gravity (in GR) is the distortion of spacetime, and that is true both inside and outside the black hole. I do agree that, we lack a useful quantum theory of gravity, but that's not the same as "we don't know what gravity is" $\endgroup$ – James K Nov 2 '15 at 18:05

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