<p>The concept of a <a href="https://en.wikipedia.org/wiki/Wormhole" rel="nofollow">wormhole</a> is, of course, highly speculative.  None the less, such a phenomenon could take many forms - most simple something which to outside observers looks like a blackhole on each end of the wormhole.  Alternatively, a <strong>traversable wormhole</strong> (see for example <a href="http://adsabs.harvard.edu/abs/1988AmJPh..56..395M" rel="nofollow">Morris &amp; Thorne 1988</a>; which has the same basic topology but no horizon), could still behave for the most part* like a normal, massive object.</p>

<p>In either case, if one end were 'swallowed' by a blackhole, it is unclear to me whether it would remain stable (i.e. remain a wormhole).  In the case of a non-traversable wormhole, <em>if it remained stable</em>, it would continue to look like a blackhole on each end --- one end of which now merged with another blackhole, and subsequently more massive.  A <strong>traversable wormhole</strong> on the other hand could (extremely hypothetically) still remain traversable if there were enough exotic matter, or it could retain the horizon from the blackhole it merged with and be <em>no-longer</em> traversable.</p>

<p>All wormhole metrics <strong><em>that I've seen</em></strong> are more or less symmetric, and thus either have no horizon, or horizons on both ends... <strong>I don't <em>think</em> it would be possible to have a horizon on only one side</strong> --- allowing something to fall into an apparent blackhole on one side, and come out of a wormhole on the other.  Even so, however, remember that a blackhole isn't a magic vacuum --- and wouldn't 'suck in' the 'entire universe'.</p>

<p>*A traversable wormhole is believed to require some sort of <em>'exotic matter'</em> in the neck, which may behave somewhat differently... </p>

CC BY-SA 3.0
2016-08-08T23:26:49.463Z
You made an interesting statement that "a blackhole ... wouldn't 'suck in' the 'entire universe'". It makes sense, of course, but it's a characterization of at least one aspect of spacetime. It would be really bad if there was something that would eat all of spacetime if it was created. I guess that the existence of the universe to this point is evidence such a thing doesn't and maybe can't exist.
Howard Miller
CC BY-SA 4.0
2022-01-14T05:13:13.247Z
One more possibility: the traversable wormhole spits the black hole out the other side. Assuming you had a traversable wormhole, this result will be dependent on trajectory and other factors.
Joshua
CC BY-SA 3.0
2015-06-08T07:51:49.970Z
I don't think you can differentiate between the two ends of a wormhole. Both ends would be the same - i.e. it's non-orientable. If there is a black hole next to a wormhole, would not the gravitational effects of the other black hole also work *through* the wormhole itself?
frodeborli
CC BY-SA 3.0
2015-01-06T22:19:47.530Z
2015-01-06T22:19:47.530Z
DilithiumMatrix
<p>Assume wormholes exist. One hole allows matter to pop out of another hole somewhere else in the universe.</p>

<p>If one end of the wormhole is swallowed by a black hole, then no information can get from that end to the other hole.</p>

<p>If the wormhole acts as some kind of gateway to another part of the universe, wouldn't that mean that the <em>entire</em> universe would be swallowed by the black hole? ie. the wormhole end is an entry portal to the entire universe, so if that is inside the black hole, wouldn't that mean the entire universe is then in the black hole?</p>

CC BY-SA 3.0
2016-01-29T11:01:24.660Z
An accurate answer isn't necessarily easy, but it appears to be well within General Relativity, and can be treated within this GR / cosmology framework.
Gerald
CC BY-SA 3.0
2016-01-29T14:36:47.390Z
I love how people are born to ask such questions. Challenging the so called frontier of physics.
LocalFluff
CC BY-SA 3.0
2016-08-08T23:22:07.290Z
Einstein did some work on something called the "Einstein - Rosen Bridge". I don't know how it differs from current thinking about wormholes. 
Unfortunately, a wormhole has to be threaded with negative energy or mass. Since negative energy/mass has not been physically observed to exist, it's a problem. 
Recently, a synthetic monopole was demonstrated using a Bose-Einstein Condensate, and I've been wondering if a synthetic wormhole could be created.
Howard Miller
CC BY-SA 3.0
2015-01-06T16:00:34.840Z
We need a [tag:speculative] tag.
HDE 226868
CC BY-SA 3.0
2015-01-06T22:01:44.560Z
I don't see any problem with this post compared to most others... Sure, it's speculative, but does that mean that there shouldn't have been questions about BHs if SE existed before the 90s?  ***If you downvote; please leave a comment to explain why.***
DilithiumMatrix
CC BY-SA 3.0
2015-01-06T23:07:12.940Z
what is a speculative tag
Oliver Watkins
CC BY-SA 3.0
2015-01-06T23:09:49.233Z
@zhermes *I didn't downvote*; I thought about voting to close. I'll leave a comment nonetheless. I think this should be closed because we don't know if wormholes exist, or how one would interact with a black hole. Answering this properly would require a long answer with general relativity - although you did a good job answering. Oliver Watkins - I meant a tag for things like this that rely on speculative concepts.
HDE 226868
CC BY-SA 3.0
2015-06-08T07:43:21.550Z
@HDE226868 Didn't Einstein predict wormholes? If you're being nitpicking - we don't even know that black holes exist. For all you know, we're all being emulated inside a computer.
frodeborli
CC BY-SA 3.0
2015-06-08T15:27:33.417Z
@frodeborli But we have solid evidence for black holes. We have no evidence for wormholes.
HDE 226868
<black-hole><wormhole>
What would happen if a wormhole gets swallowed by a black hole?
Oliver Watkins
# What would happen if a wormhole gets swallowed by a black hole?

(Asked by: username_0 on 2015-01-06)

Assume wormholes exist. One hole allows matter to pop out of another hole somewhere else in the universe.

If one end of the wormhole is swallowed by a black hole, then no information can get from that end to the other hole.

If the wormhole acts as some kind of gateway to another part of the universe, wouldn't that mean that the *entire* universe would be swallowed by the black hole? ie. the wormhole end is an entry portal to the entire universe, so if that is inside the black hole, wouldn't that mean the entire universe is then in the black hole?

**Tags:** black-hole, wormhole
> **Comments:**
> **username_4**: We need a [tag:speculative] tag.  
> **username_5**: I don't see any problem with this post compared to most others... Sure, it's speculative, but does that mean that there shouldn't have been questions about BHs if SE existed before the 90s?  ***If you downvote; please leave a comment to explain why.***  
> **username_0**: what is a speculative tag  
> **username_4**: @zhermes *I didn't downvote*; I thought about voting to close. I'll leave a comment nonetheless. I think this should be closed because we don't know if wormholes exist, or how one would interact with a black hole. Answering this properly would require a long answer with general relativity - although you did a good job answering. Oliver Watkins - I meant a tag for things like this that rely on speculative concepts.  
> **username_6**: @HDE226868 Didn't Einstein predict wormholes? If you're being nitpicking - we don't even know that black holes exist. For all you know, we're all being emulated inside a computer.  
> **username_4**: @frodeborli But we have solid evidence for black holes. We have no evidence for wormholes.  
> **username_1**: An accurate answer isn't necessarily easy, but it appears to be well within General Relativity, and can be treated within this GR / cosmology framework.  
> **username_2**: I love how people are born to ask such questions. Challenging the so called frontier of physics.  
> **username_3**: Einstein did some work on something called the "Einstein - Rosen Bridge". I don't know how it differs from current thinking about wormholes.  Unfortunately, a wormhole has to be threaded with negative energy or mass. Since negative energy/mass has not been physically observed to exist, it's a problem.  Recently, a synthetic monopole was demonstrated using a Bose-Einstein Condensate, and I've been wondering if a synthetic wormhole could be created.  

---

## 1 answers

### Answer by username_5 on 2015-01-06. Score: 3

The concept of a [wormhole](https://en.wikipedia.org/wiki/Wormhole) is, of course, highly speculative. None the less, such a phenomenon could take many forms - most simple something which to outside observers looks like a blackhole on each end of the wormhole. Alternatively, a **traversable wormhole** (see for example [Morris & Thorne 1988](http://adsabs.harvard.edu/abs/1988AmJPh..56..395M); which has the same basic topology but no horizon), could still behave for the most part\* like a normal, massive object.

In either case, if one end were 'swallowed' by a blackhole, it is unclear to me whether it would remain stable (i.e. remain a wormhole). In the case of a non-traversable wormhole, *if it remained stable*, it would continue to look like a blackhole on each end --- one end of which now merged with another blackhole, and subsequently more massive. A **traversable wormhole** on the other hand could (extremely hypothetically) still remain traversable if there were enough exotic matter, or it could retain the horizon from the blackhole it merged with and be *no-longer* traversable.

All wormhole metrics ***that I've seen*** are more or less symmetric, and thus either have no horizon, or horizons on both ends... **I don't *think* it would be possible to have a horizon on only one side** --- allowing something to fall into an apparent blackhole on one side, and come out of a wormhole on the other. Even so, however, remember that a blackhole isn't a magic vacuum --- and wouldn't 'suck in' the 'entire universe'.

\*A traversable wormhole is believed to require some sort of *'exotic matter'* in the neck, which may behave somewhat differently...

> **Comments:**
> **username_6**: I don't think you can differentiate between the two ends of a wormhole. Both ends would be the same - i.e. it's non-orientable. If there is a black hole next to a wormhole, would not the gravitational effects of the other black hole also work *through* the wormhole itself?  
> **username_3**: You made an interesting statement that "a blackhole ... wouldn't 'suck in' the 'entire universe'". It makes sense, of course, but it's a characterization of at least one aspect of spacetime. It would be really bad if there was something that would eat all of spacetime if it was created. I guess that the existence of the universe to this point is evidence such a thing doesn't and maybe can't exist.  
> **username_7**: One more possibility: the traversable wormhole spits the black hole out the other side. Assuming you had a traversable wormhole, this result will be dependent on trajectory and other factors.  

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