<p>The simplified answer is: Due to <a href="http://en.wikipedia.org/wiki/Gravitational_time_dilation" rel="nofollow noreferrer">gravitational time dilation</a>.</p>

<p>That's a consequence of <a href="http://en.wikipedia.org/wiki/General_relativity" rel="nofollow noreferrer">general relativity</a>. One fundamental idea of general relativity is the <a href="http://en.wikipedia.org/wiki/Equivalence_principle" rel="nofollow noreferrer">equivalence of inertial and gravitational mass</a>, meaning forces induced by acceleration aren't distinguishable from gravity.
Persuing this principle together with the constant speed of light lead to <a href="http://en.wikipedia.org/wiki/Einstein_field_equations" rel="nofollow noreferrer">Einstein's field equations</a>. One of the solutions of these equations is the <a href="http://en.wikipedia.org/wiki/Schwarzschild_metric" rel="nofollow noreferrer">Schwarzschild solution</a> for non-rotating, electrically neutral black holes.
This solution can be used to derive gravitational time dilation, as part of <a href="https://physics.stackexchange.com/questions/3009/how-exactly-does-curved-space-time-describe-the-force-of-gravity">spacetime warp</a> near mass/energy.
(<a href="http://www.youtube.com/watch?v=foRPKAKZWx8" rel="nofollow noreferrer">Introductory video to general relativity</a>)</p>

<p>A black hole provides a way to go faster into the future of a region of higher gravitational potential away from the black hole.
But the body near the black hole needs to withstand the high gravity. Circular orbits around a black hole are only possible down to 3/2 times, stable only down to 3 times, the <a href="http://en.wikipedia.org/wiki/Schwarzschild_geodesics" rel="nofollow noreferrer">Schwarzschild radius</a>.</p>

CC BY-SA 3.0
2014-03-17T22:04:02.080Z
2014-03-17T22:04:02.080Z
2017-04-13T12:40:15.377Z
Gerald
<p>Time does <b>not</b> pass slower near a black hole.  Stay-Home-Sally far from a black hole observing Astro-Bob descending into a black hole would see Bob's time passing slower as Bob neared the event horizon, but Bob would not experience this. On the contrary, Bob, looking back at Sally, would see time pass faster for her as he neared the event horizon.</p>

<p>Who is right, or is time relative to the motion of the observers? </p>

CC BY-SA 3.0
2014-03-25T22:25:46.720Z
2014-03-25T22:25:46.720Z
Marc
<p>Why exactly does time get slow around a black hole? And does it provide a way to go into the future?</p>

CC BY-SA 3.0
2014-03-21T15:32:23.633Z
This question would possibly belong on Physics.SE
Rory Alsop
<black-hole><space-time>
Why does time get slow near a black hole?
user1091
# Why does time get slow near a black hole?

(Asked by: username_0 on 2014-03-17)

Why exactly does time get slow around a black hole? And does it provide a way to go into the future?

**Tags:** black-hole, space-time

> **Comments:**
> **username_1**: This question would possibly belong on Physics.SE  

---

## 2 answers

### Answer by username_2 on 2014-03-17. Score: 3

The simplified answer is: Due to [gravitational time dilation](http://en.wikipedia.org/wiki/Gravitational_time_dilation).

That's a consequence of [general relativity](http://en.wikipedia.org/wiki/General_relativity). One fundamental idea of general relativity is the [equivalence of inertial and gravitational mass](http://en.wikipedia.org/wiki/Equivalence_principle), meaning forces induced by acceleration aren't distinguishable from gravity.
Persuing this principle together with the constant speed of light lead to [Einstein's field equations](http://en.wikipedia.org/wiki/Einstein_field_equations). One of the solutions of these equations is the [Schwarzschild solution](http://en.wikipedia.org/wiki/Schwarzschild_metric) for non-rotating, electrically neutral black holes.
This solution can be used to derive gravitational time dilation, as part of [spacetime warp](https://physics.stackexchange.com/questions/3009/how-exactly-does-curved-space-time-describe-the-force-of-gravity) near mass/energy.
([Introductory video to general relativity](http://www.youtube.com/watch?v=foRPKAKZWx8))

A black hole provides a way to go faster into the future of a region of higher gravitational potential away from the black hole.
But the body near the black hole needs to withstand the high gravity. Circular orbits around a black hole are only possible down to 3/2 times, stable only down to 3 times, the [Schwarzschild radius](http://en.wikipedia.org/wiki/Schwarzschild_geodesics).


---

### Answer by username_3 on 2014-03-25. Score: 3

Time does **not** pass slower near a black hole. Stay-Home-Sally far from a black hole observing Astro-Bob descending into a black hole would see Bob's time passing slower as Bob neared the event horizon, but Bob would not experience this. On the contrary, Bob, looking back at Sally, would see time pass faster for her as he neared the event horizon.

Who is right, or is time relative to the motion of the observers?


---

