# Wormhole physics

## Main Question or Discussion Point

I have been reading up on wormholes and though I can't claim to understand every thing I've read there is one thing that I have to wonder about. from what I've read I understand that a wormhole has to have at least two mouths and that it is theoretically possible for the multiple mouths to be clustered together. Is it possible however for a single wormhole to have more than two mouths?

## Answers and Replies

Related Astronomy and Astrophysics News on Phys.org
I have been reading up on wormholes and though I can't claim to understand every thing I've read there is one thing that I have to wonder about. from what I've read I understand that a wormhole has to have at least two mouths and that it is theoretically possible for the multiple mouths to be clustered together. Is it possible however for a single wormhole to have more than two mouths?
I dont think that wormholes might be having two mouths ! Basically a wormhole acts as a neck between its front mouth(blackhole) and its rear mouth(white hole). It is very hard to say that wormholes lie between two spaces i.e between two spacetime graphs. so the possibility of the third mouth could be between these two graphs but there exists no spacetime graph between two spaces ! so no possibility of the third mouth.

I have been reading up on wormholes and though I can't claim to understand every thing I've read there is one thing that I have to wonder about. from what I've read I understand that a wormhole has to have at least two mouths and that it is theoretically possible for the multiple mouths to be clustered together. Is it possible however for a single wormhole to have more than two mouths?

Danger
Gold Member
Welcome to PF, Godspanther.
As far as I understand wormholes, they have to have 2 'mouths'—one a each end.

I strongly suspect that this thread will be moved to the Astrophysics section.

Last edited by a moderator:
I tried astrophysics first.

the single reply I got did not answer my question sufficiently.

also

what kind of effects, gravity, radiation, radio waves, distortions etc could one theoretically expect in the vicinity of a wormhole aperture?

what kind of effects, gravity, radiation, radio waves, distortions etc could one theoretically expect in the vicinity of a wormhole aperture?
if we think theorotically then there can be gravitational or magnetic feild around a wormhole ! these fields can show fluctuations in the form of particle-antiparticle pair which may result into hawking radiation. afterall its very hard to say that wormhole has an eventhorizon. the second possibility is existance of tidal forces in the vicinity of a wormhole. thats it ! i cant think much more theorotical because of the absence of the spacetime graph.

I saw this question and anwer in a http://www.webfilesuci.org/WormholeFAQ.html" [Broken]. It describes how to a make a 3-mouthed wormhole and asserts that the procedure can be extended to any number of mouths.

Is it possible to create a network of wormholes in which any wormhole mouth could be used to reach multiple destinations directly?
Yes. Assuming that it’s possible to create a single wormhole, the creation of a network of many is not particularly far fetched. You would proceed as follows: 1) Create a wormhole that connects locations A and B. 2) Create another wormhole connecting locations A and C. There are now two wormhole mouths at the location A – one that leads to B and another that leads to C. 3) Move the A mouth of the AC wormhole into the A mouth of the AB wormhole until the A mouth of AC is at the throat of the AB wormhole. 4) You now have a wormhole network in which there is a non-stop connection between any of A, B, and C. Repeat the procedure to add other destinations. 5) Ease congestion at the throat nexus by expanding it (with additional exotic matter) and by adding an automated system that properly routes spacecraft based on their transmitted destination codes.

Last edited by a moderator:
I saw this question and anwer in a http://www.webfilesuci.org/WormholeFAQ.html" [Broken]. It describes how to a make a 3-mouthed wormhole and asserts that the procedure can be extended to any number of mouths.

Is it possible to create a network of wormholes in which any wormhole mouth could be used to reach multiple destinations directly?
Yes. Assuming that it’s possible to create a single wormhole, the creation of a network of many is not particularly far fetched. You would proceed as follows: 1) Create a wormhole that connects locations A and B. 2) Create another wormhole connecting locations A and C. There are now two wormhole mouths at the location A – one that leads to B and another that leads to C. 3) Move the A mouth of the AC wormhole into the A mouth of the AB wormhole until the A mouth of AC is at the throat of the AB wormhole. 4) You now have a wormhole network in which there is a non-stop connection between any of A, B, and C. Repeat the procedure to add other destinations. 5) Ease congestion at the throat nexus by expanding it (with additional exotic matter) and by adding an automated system that properly routes spacecraft based on their transmitted destination codes.
This article gives some more details of the idea: http://philsci-archive.pitt.edu/3783/. Note that however, it has not been peer-reviewed or published. I don't know of any published result on the feasibility of such wormhole network.

Last edited by a moderator:
I dont think that wormholes might be having two mouths ! Basically a wormhole acts as a neck between its front mouth(blackhole) and its rear mouth(white hole). It is very hard to say that wormholes lie between two spaces i.e between two spacetime graphs. so the possibility of the third mouth could be between these two graphs but there exists no spacetime graph between two spaces ! so no possibility of the third mouth.
Wormholes don't require black and white holes.
I saw this question and anwer in a http://www.webfilesuci.org/WormholeFAQ.html" [Broken]. It describes how to a make a 3-mouthed wormhole and asserts that the procedure can be extended to any number of mouths.

Is it possible to create a network of wormholes in which any wormhole mouth could be used to reach multiple destinations directly?
Yes. Assuming that it’s possible to create a single wormhole, the creation of a network of many is not particularly far fetched. You would proceed as follows: 1) Create a wormhole that connects locations A and B. 2) Create another wormhole connecting locations A and C. There are now two wormhole mouths at the location A – one that leads to B and another that leads to C. 3) Move the A mouth of the AC wormhole into the A mouth of the AB wormhole until the A mouth of AC is at the throat of the AB wormhole. 4) You now have a wormhole network in which there is a non-stop connection between any of A, B, and C. Repeat the procedure to add other destinations. 5) Ease congestion at the throat nexus by expanding it (with additional exotic matter) and by adding an automated system that properly routes spacecraft based on their transmitted destination codes.
This is far too speculative for my liking.

Too many assumptions being made to get to this point.

Given we don't know wormholes exist, it's going a bit far to talk about manipulating them in such a way, with such confidence.

Last edited by a moderator:
Ryan_m_b
Staff Emeritus
I saw this question and anwer in a http://www.webfilesuci.org/WormholeFAQ.html" [Broken]. It describes how to a make a 3-mouthed wormhole and asserts that the procedure can be extended to any number of mouths.

Is it possible to create a network of wormholes in which any wormhole mouth could be used to reach multiple destinations directly?
Yes. Assuming that it’s possible to create a single wormhole, the creation of a network of many is not particularly far fetched. You would proceed as follows: 1) Create a wormhole that connects locations A and B. 2) Create another wormhole connecting locations A and C. There are now two wormhole mouths at the location A – one that leads to B and another that leads to C. 3) Move the A mouth of the AC wormhole into the A mouth of the AB wormhole until the A mouth of AC is at the throat of the AB wormhole. 4) You now have a wormhole network in which there is a non-stop connection between any of A, B, and C. Repeat the procedure to add other destinations. 5) Ease congestion at the throat nexus by expanding it (with additional exotic matter) and by adding an automated system that properly routes spacecraft based on their transmitted destination codes.
This is indeed far too speculative. If you could create wormholes then you could not put the mouth of one in the other. If you have two wormhole mouths of 1000kg mass and you sent 100kg through mouth A (so that it came out of mouth B) The mass of A would change to 1100kg and the mass of B to 900kg. If you put wormhole mouth C into A you would change B's mass to 0kg and thus destroy it. There was a thread on here a little while ago talking about this.

The other problem is causality. If you built a wormhole network (not by having the mouths in each other but having B physically close to C) you would have to be very careful not to arrange it so as to allow particles to enter their own past light cone. In theory you would either have just made a time machine or vacuum fluctuations would immediately destroy all the wormholes.

It is not certain whether or not wormholes could even exist however so talking too much about "wormhole physics" is bound to stray into over-speculation

Last edited by a moderator:
This is indeed far too speculative. If you could create wormholes then you could not put the mouth of one in the other. If you have two wormhole mouths of 1000kg mass and you sent 100kg through mouth A (so that it came out of mouth B) The mass of A would change to 1100kg and the mass of B to 900kg. If you put wormhole mouth C into A you would change B's mass to 0kg and thus destroy it. There was a thread on here a little while ago talking about this.

The other problem is causality. If you built a wormhole network (not by having the mouths in each other but having B physically close to C) you would have to be very careful not to arrange it so as to allow particles to enter their own past light cone. In theory you would either have just made a time machine or vacuum fluctuations would immediately destroy all the wormholes.

It is not certain whether or not wormholes could even exist however so talking too much about "wormhole physics" is bound to stray into over-speculation
If you attached both mouths, wouldn't you have something like a Klein Bottle?

Ryan_m_b
Staff Emeritus
If you attached both mouths, wouldn't you have something like a Klein Bottle?
What do you mean by attached? The two mouths of wormholes are linked from beginning to end, it is impossible to switch what they are linked to.

What do you mean by attached? The two mouths of wormholes are linked from beginning to end, it is impossible to switch what they are linked to.
So are the mouths of a kaluza-klein manifold of the 'bottle' type; I was curious if that was what you were getting at. The mouth at either "end" is the same thing, but the topography is not the usual wormhole because it would feed into itself. I suppose this would be a kind of CTC, but I was asking a question, not posing an answer. I don't know much about this, you see.

There's no theory stating that wormholes have more than two mouths. But I think it could be possible. Think about this, there's a network of three blackholes, and three whiteholes, all connected by a single wormhole. kind of like the way many rivers flow into a single big river. That could be possible. If one were to enter any one of those three blackholes, we would randomly come out of any one of the whiteholes.

Ryan_m_b
Staff Emeritus
There's no theory stating that wormholes have more than two mouths. But I think it could be possible. Think about this, there's a network of three blackholes, and three whiteholes, all connected by a single wormhole. kind of like the way many rivers flow into a single big river. That could be possible. If one were to enter any one of those three blackholes, we would randomly come out of any one of the whiteholes.
You're going to have to provide citations for that idea rather than analogy.

I think you have a misunderstanding though, Schwarzschild wormholes would result in a black hole and white hole. Traversable wormholes such as a Morris-Thorne wormhole link two points in space only requiring no black/white holes.

So are the mouths of a kaluza-klein manifold of the 'bottle' type; I was curious if that was what you were getting at. The mouth at either "end" is the same thing, but the topography is not the usual wormhole because it would feed into itself. I suppose this would be a kind of CTC, but I was asking a question, not posing an answer. I don't know much about this, you see.
I don't know too much about it either so I'm not sure what the topography would be like. However if they could be made wormhole mouths would always be attached linking two points in space. Your first comment asking "if you attached them" is what I was replying to as there is no other way they can be. If that makes sense?

Last edited:
You're going to have to provide citations for that idea rather than analogy.

I think you have a misunderstanding though, Schwarzschild wormholes would result in a black hole and white hole. Traversable wormholes such as a Morris-Thorne wormhole link two points in space only requiring no black/white holes.

I don't know too much about it either so I'm not sure what the topography would be like. However if they could be made wormhole mouths would always be attached linking two points in space. Your first comment asking "if you attached them" is what I was replying to as there is no other way they can be. If that makes sense?
I'm not sure; what I'm talking about is still a same-mouth entity where the difference is the topography, not the nature of the mouths. You're right that this kind of wormhole wouldn't link different points; you'd take a journey only to the precise point in space that you started. I think that's what you're driving at, so you'd be right.

This is indeed far too speculative. If you could create wormholes then you could not put the mouth of one in the other. If you have two wormhole mouths of 1000kg mass and you sent 100kg through mouth A (so that it came out of mouth B) The mass of A would change to 1100kg and the mass of B to 900kg. If you put wormhole mouth C into A you would change B's mass to 0kg and thus destroy it. There was a thread on here a little while ago talking about this.

The other problem is causality. If you built a wormhole network (not by having the mouths in each other but having B physically close to C) you would have to be very careful not to arrange it so as to allow particles to enter their own past light cone. In theory you would either have just made a time machine or vacuum fluctuations would immediately destroy all the wormholes.

It is not certain whether or not wormholes could even exist however so talking too much about "wormhole physics" is bound to stray into over-speculation
Yes it's speculative alright, but only because the entire topic of wormholes is speculative, as was the topic of black holes for most of the 20th century.

The objection that you raise involving excess mass seems to be totally abatable, though. I think that you could compensate for the extra mass by throwing in more exotic matter. And you must assume that that exists, if you have already assumed that it's possible to make a single traversable wormhole.

As to your second point about causality, the same http://www.webfilesuci.org/WormholeFAQ.html" [Broken] seems to have an answer for that:

Don’t quantum effects prevent wormholes from being turned into time machines?
No. It’s true that calculations seem to show that a wormhole-destroying feedback loop of virtual particles appears whenever a wormhole is configured as a time machine. But these calculations don’t assume the existence of the parallel universes that would have prevented the feedback. Even without this assumption, it’s possible to make the feedback arbitrarily small by replacing the single wormhole with a Roman ring of wormholes.

What is a Roman ring?
An arrangement of several wormholes that functions collectively as a time machine, even though no subset of the wormholes functions as one.
----

This FAQ is an excerpt from a book that explains this in detail and cites the corresponding references in the physics literature.

Last edited by a moderator:
Ryan_m_b
Staff Emeritus
Yes it's speculative alright, but only because the entire topic of wormholes is speculative, as was the topic of black holes for most of the 20th century.

The objection that you raise involving excess mass seems to be totally abatable, though. I think that you could compensate for the extra mass by throwing in more exotic matter. And you must assume that that exists, if you have already assumed that it's possible to make a single traversable wormhole.

As to your second point about causality, the same http://www.webfilesuci.org/WormholeFAQ.html" [Broken] seems to have an answer for that:

Don’t quantum effects prevent wormholes from being turned into time machines?
No. It’s true that calculations seem to show that a wormhole-destroying feedback loop of virtual particles appears whenever a wormhole is configured as a time machine. But these calculations don’t assume the existence of the parallel universes that would have prevented the feedback. Even without this assumption, it’s possible to make the feedback arbitrarily small by replacing the single wormhole with a Roman ring of wormholes.

What is a Roman ring?
An arrangement of several wormholes that functions collectively as a time machine, even though no subset of the wormholes functions as one.
----

This FAQ is an excerpt from a book that explains this in detail and cites the corresponding references in the physics literature.
Throwing more exotic matter might help or you could just send a mass the other way once travelers have gone through i.e. have a series of 1 tonne probes orbiting the wormhole and once a ship has gone through send a series of probes through the other way to cancel out the mass change.

I really don't get the parallel universe thing and how that would help. If the wormhole connects to another universe then time travel won't apply. If quantum fluctuations or even real particles would cause a wormhole to collapse then a roman ring wouldn't help, no matter how you do it when the QFs or real particles enter their own past light cone the wormholes will collapse.

If CPCs don't exist though the Novikov self-consistency principle might prevent any possibility of changing the past.

Last edited by a moderator:
JesseM
As to your second point about causality, the same http://www.webfilesuci.org/WormholeFAQ.html" seems to have an answer for that:

Don’t quantum effects prevent wormholes from being turned into time machines?
No. It’s true that calculations seem to show that a wormhole-destroying feedback loop of virtual particles appears whenever a wormhole is configured as a time machine. But these calculations don’t assume the existence of the parallel universes that would have prevented the feedback. Even without this assumption, it’s possible to make the feedback arbitrarily small by replacing the single wormhole with a Roman ring of wormholes.

What is a Roman ring?
An arrangement of several wormholes that functions collectively as a time machine, even though no subset of the wormholes functions as one.
This is based on calculations in semiclassical gravity though, and many physicists would argue they just suggest that semiclassical gravity is probably no longer a good approximation to quantum gravity in situations involving wormholes. For example, see this paper on Roman rings by wormhole expert Matt Visser (author of the textbook Lorentzian Wormholes: From Einstein to Hawking), where in the conclusion on p. 4 he writes: "My interpretation is perhaps a little different: I view this not as a vindication for time travel enthusiasts but rather as an indication that resolving issues of chronology protection requires a fully developed theory of quantum gravity [5]."

Last edited by a moderator:
I really don't get the parallel universe thing and how that would help. If the wormhole connects to another universe then time travel won't apply.
Yeah, there's a FAQ (answer) for that:

Isn’t time travel by wormhole or any other means impossible due to the paradoxes that it implies?
Not necessarily. Dealing with time travel paradoxes by conjecturing the impossibility of time travel is only one of three ways of resolving the issue. The other ways are:
1) Impose self consistency on classical physics: A time traveler cannot change the past because he was always part of it. When he attempts to change the past, his efforts will be thwarted by an apparent conspiracy of events. 2) Impose self consistency on quantum physics: A time traveler cannot change the past because all possible pasts have already occurred in parallel universes. When he attempts to change the past, his efforts will not seem to him to be thwarted. This is because he will have entered the past of a preexisting parallel universe in which he has already made the changes that he seeks to effect.

If quantum fluctuations or even real particles would cause a wormhole to collapse then a roman ring wouldn't help, no matter how you do it when the QFs or real particles enter their own past light cone the wormholes will collapse.
http://arxiv.org/abs/gr-qc/9702043" [Broken] that the semi-classical calculation of the wormhole destroying feedback loop of virtual particles is unrealiable, because semi-classical calculations also show that these effects can be made arbitrarily small with a Roman ring. Here's the abstract for his 1997 paper entitled, "Traversable wormholes: the Roman ring":

"In this brief report I introduce a yet another class of geometries for which semi-classical chronology protection theorems are of dubious physical reliability. I consider a Roman ring'' of traversable wormholes, wherein a number of wormholes are arranged in a ring in such a manner that no subset of wormholes is near to chronology violation, though the combined system can be arbitrarily close to chronology violation. I show that (with enough wormholes in the ring) the gravitational vacuum polarization (the expectation value of the quantum stress-energy tensor) can be made arbitrarily small. In particular the back-reaction can be kept arbitrarily small all the way to the reliability horizon''---so that semi-classical quantum gravity becomes unreliable before the gravitational back reaction becomes large."

Last edited by a moderator:
Ryan_m_b
Staff Emeritus
Yeah, there's a FAQ (answer) for that:

Isn’t time travel by wormhole or any other means impossible due to the paradoxes that it implies?
Not necessarily. Dealing with time travel paradoxes by conjecturing the impossibility of time travel is only one of three ways of resolving the issue. The other ways are:
1) Impose self consistency on classical physics: A time traveler cannot change the past because he was always part of it. When he attempts to change the past, his efforts will be thwarted by an apparent conspiracy of events. 2) Impose self consistency on quantum physics: A time traveler cannot change the past because all possible pasts have already occurred in parallel universes. When he attempts to change the past, his efforts will not seem to him to be thwarted. This is because he will have entered the past of a preexisting parallel universe in which he has already made the changes that he seeks to effect.
Yeah I got that my point was that it's not really time travel if you are travelling to another universe because you haven't arrived in you're past light cone, you've arrived in a universe which is exactly the same as conditions at the time you were aiming for in your past light cone.

http://arxiv.org/abs/gr-qc/9702043" [Broken] that the semi-classical calculation of the wormhole destroying feedback loop of virtual particles is unrealiable, because semi-classical calculations also show that these effects can be made arbitrarily small with a Roman ring. Here's the abstract for his 1997 paper entitled, "Traversable wormholes: the Roman ring":

"In this brief report I introduce a yet another class of geometries for which semi-classical chronology protection theorems are of dubious physical reliability. I consider a Roman ring'' of traversable wormholes, wherein a number of wormholes are arranged in a ring in such a manner that no subset of wormholes is near to chronology violation, though the combined system can be arbitrarily close to chronology violation. I show that (with enough wormholes in the ring) the gravitational vacuum polarization (the expectation value of the quantum stress-energy tensor) can be made arbitrarily small. In particular the back-reaction can be kept arbitrarily small all the way to the reliability horizon''---so that semi-classical quantum gravity becomes unreliable before the gravitational back reaction becomes large."
I'll admit that the maths here is beyond me so maybe that's why I can't understand why a roman ring would avoid the problem. If the quantum fluctuations get back inside their own past light cone via any mechanism surely that should lead to collapse? However I feel I should conclude the same way Visser has

I view this not as a vindication for time travel enthusiasts but rather as an indication that resolving issues of chronology protection requires a fully developed theory of quantum gravity

Last edited by a moderator: