Wormhole Creation: Theoretical Methods and Questions

[TheTraveler]

Hello, I'm a liberal arts type with an interest in wormholes, so bear with my "science".

From my readings, there are two (highly theoretically, of course) ways of creating a wormhole:

1. Focus a galactic-level beam of energy/mass at a single point. This will create a naked singularity that would somehow create a twin singularity elsewhere in the universe. A tunnel would exist between these singularities. Then you dump in a massive amount of exotic matter, whose negative mass would largely negate the gravity of the singularities and change them into transversable mouths.

2. Natural wormholes pop in and out of existence at the Planck level. One of these wormholes would be grabbed from this "quantum foam", probably by means requiring a massive amount of energy as well. By focus energy at this wormhole, it grows to a macroscopic size. Although this is not a singularity, it is a heavily dense object because of the massive energy poured into it to inflate it. Now you pour massive amounts of exotic matter to hold it open and prevent it from collapsing in on itself.

My questions are:

1. Am I getting these ideas right, or am I off the mark?

2. Is the first method classical? I understand the second is quantum, but is the first classical?

3. In both methods, is the location of the second mouth entirely random? I just don't understand where the second mouth comes from, in either method. Do quantum wormholes and singularities naturally "reach out across the universe" and somehow pair up with a "kindred spirit" (i.e., another singularity or quantum wormhole mouth) randomly. Or would controlling the level of positive energy pumped into it (during inflation) also control how and where the wormhole connects to?

4. For the first method, rather than just creating your own singularity, could you not instead dump a massive amount of exotic (negative mass) matter into an existing Kerr black hole? Dump enough of this matter into it, then it would eventually evaporate, right? Once evaporated, would you not have a ring-shaped singularity that acts like a wormhole then? Wouldn't the exotic matter negate the gravitational pull of the black hole, and in turn destroy its event horizon and make it safe to go through?

Again, I understand this is all theoretical, I was just curious if there are any experts out there that could illuminate some of these points that I am struggling with. Thanks!

 

[Nabeshin]

Hey TheTraveller and welcome to Physics Forums!

As you note, the study of wormholes is highly theoretical at this point. Much of what is written and heard about wormholes is derived through heuristic arguments in which we are sort of smelling our way to what we think the answer might be. So, while we can use Einstein's theory of General Relativity to describe static (unchanging) wormholes, we basically have to wave our hands around to talk about them changing or interacting with the environment.

That said, let me address a few of your questions.

1. This doesn't make any sense. There is no reason to think that the singularity formed here would be naked, so you would just produce a black hole.

2. This is slightly more plausible. Again, though, we sort of have this notion of Planck scale wormholes that comes from heuristic arguments in typical variations in the metric at the Planck scale. And then we sort of wave our hands around and note that negative energy stabilizes the throat, so we maybe say we could inflate such a hole to macroscopic sizes. It's certainly far from clear if this is possible, and will likely require a full theory of quantum gravity for us to be sure. But this one has at least more basis than the first.

3. This is actually a question I've never seen directly answered in the literature. Again, this is likely because the dynamics of these objects are very poorly understood, so we can only talk about the (Semi)precisely once they have already formed. It seems to me that it cannot be random though. The overall geometry and topology of the universe should determine, to at least some probabilistic distribution, where the other mouth of an intra-universe wormhole would land. Some remarks in Matt Visser's "Lorentzian Wormholes" make me think he agrees that there should be some control over where the "other end" lands.

4. It's not entirely clear what happens when a black hole evaporates, but most people's money is against naked singularities.

 

[Chronos]

Naked singularities? Not the sort of thing discussed in polite company. As I recall Stephen Hawking and Rodger Penrose has a long running bet that Hawking eventually conceded [Hawking on the pro side]. I have no clue how you would manipulate the location of the 'outlet' of a wormhole. I would guess the distance should somehow be related to the energy input, but, that is purely speculative. Furthermore, it could be hugely difficult to stabilize the outlet position - which might be an issue for prospective explorers.

BTW, A black hole need not expire until it reaches Planck mass. It can no longer remain a black hole at that point. No gigantic explosion, just a gamma 'poof'. On the other hand, this is why I see no possibility of creating a miniature black hole with the LHC. The Planck mass is still many orders of magnitude above those accessible by the LHC.

 

[dimension10]

Hello, I'm a liberal arts type with an interest in wormholes, so bear with my "science".

From my readings, there are two (highly theoretically, of course) ways of creating a wormhole:

1. Focus a galactic-level beam of energy/mass at a single point. This will create a naked singularity that would somehow create a twin singularity elsewhere in the universe. A tunnel would exist between these singularities. Then you dump in a massive amount of exotic matter, whose negative mass would largely negate the gravity of the singularities and change them into transversable mouths.

2. Natural wormholes pop in and out of existence at the Planck level. One of these wormholes would be grabbed from this "quantum foam", probably by means requiring a massive amount of energy as well. By focus energy at this wormhole, it grows to a macroscopic size. Although this is not a singularity, it is a heavily dense object because of the massive energy poured into it to inflate it. Now you pour massive amounts of exotic matter to hold it open and prevent it from collapsing in on itself.

My questions are:

1. Am I getting these ideas right, or am I off the mark?

2. Is the first method classical? I understand the second is quantum, but is the first classical?

3. In both methods, is the location of the second mouth entirely random? I just don't understand where the second mouth comes from, in either method. Do quantum wormholes and singularities naturally "reach out across the universe" and somehow pair up with a "kindred spirit" (i.e., another singularity or quantum wormhole mouth) randomly. Or would controlling the level of positive energy pumped into it (during inflation) also control how and where the wormhole connects to?

4. For the first method, rather than just creating your own singularity, could you not instead dump a massive amount of exotic (negative mass) matter into an existing Kerr black hole? Dump enough of this matter into it, then it would eventually evaporate, right? Once evaporated, would you not have a ring-shaped singularity that acts like a wormhole then? Wouldn't the exotic matter negate the gravitational pull of the black hole, and in turn destroy its event horizon and make it safe to go through?

Again, I understand this is all theoretical, I was just curious if there are any experts out there that could illuminate some of these points that I am struggling with. Thanks!

I guess wormholes can't exist? I mean a wormhole is connected to a white hole so wouldn't antigravity speed up time? and stephen hawking proved that's wrong? i think in the first idea a black hole will be produced.

 

[TheTraveler]

3. This is actually a question I've never seen directly answered in the literature. Again, this is likely because the dynamics of these objects are very poorly understood, so we can only talk about the (Semi)precisely once they have already formed. It seems to me that it cannot be random though. The overall geometry and topology of the universe should determine, to at least some probabilistic distribution, where the other mouth of an intra-universe wormhole would land. Some remarks in Matt Visser's "Traversable Wormholes" make me think he agrees that there should be some control over where the "other end" lands.

Thanks for all the feedback!

OK, so "random" isn't the correct way to describe where the other end will be at. You are saying that if an advanced civilization in Andromeda "grabs" a quantum wormhole, they will have a .05 probability that it will lead to a place around Vega, a .01 probability that it will lead to Alpha Centari, a .10 probability that it will lead to my living room (I better tidy up if I have company arriving), etc. So it is still sort of a game of change, but an advanced civilization with super computers could map the topology of the universe as they know it, and from that make estimated guesses about where a quantum wormhole will lead to. Do I (more or less) understand this correctly?

 

[Nabeshin]

You are saying that if an advanced civilization in Andromeda "grabs" a quantum wormhole, they will have a .05 probability that it will lead to a place around Vega, a .01 probability that it will lead to Alpha Centari, a .10 probability that it will lead to my living room (I better tidy up if I have company arriving), etc. So it is still sort of a game of change, but an advanced civilization with super computers could map the topology of the universe as they know it, and from that make estimated guesses about where a quantum wormhole will lead to. Do I (more or less) understand this correctly?

You understand my inkling of it correctly, yes. But don't go around quoting this as fact! This is merely the hunch I have about the matter, and isn't really substantiated by any evidence (theoretical or otherwise!). Especially with quantum wormholes, it just seems inevitable (to me) that there must be some kind of probabilistic distribution of how it is connected.

 

[TheTraveler]

Naked singularities? Not the sort of thing discussed in polite company.

Things to never discuss in polite company:

1. Religion
2. Politics
3. Backwards time travel

Now I will add naked singularities to this list :)

Thanks for the feedback. I think I read in the forums about creating a singularity for the purpose of a wormhole, but after all this feedback a black hole sounds like a dead end (pun completely intended).

 

[TheTraveler]

You understand my inkling of it correctly, yes. But don't go around quoting this as fact! This is merely the hunch I have about the matter, and isn't really substantiated by any evidence (theoretical or otherwise!). Especially with quantum wormholes, it just seems inevitable (to me) that there must be some kind of probabilistic distribution of how it is connected.

Thanks, that actually clears up a few cobwebs for me. Dr. Thorne's "Black Holes and time warps" mentioned the probability of the topology within the quantum foam, and I really couldn't follow what he was getting at. I think this was what he was explaining, and I get it now.

One last question I forgot to ask:

Would a wormhole's mouths be massively heavy, or neutral? I read (http://news.nationalgeographic.com/news/2005/09/0916_050916_timetravel_2.html) that a wormhole mouth would weigh a 100 million solar masses, is that right? Wouldn't the exotic matter threading the wormhole negate this massive weight? Or at least bring it down to significantly?

That article is the only place that I've ever read about the weight of a wormhole mouth, but I would think that exotic matter could be used to negate the positive mass of the mouths; otherwise, the mouths would collapse in on themselves and create event horizons, right?

 

[Nicodemus]

Thanks, that actually clears up a few cobwebs for me. Dr. Thorne's "Black Holes and time warps" mentioned the probability of the topology within the quantum foam, and I really couldn't follow what he was getting at. I think this was what he was explaining, and I get it now.

One last question I forgot to ask:

Would a wormhole's mouths be massively heavy, or neutral? I read (http://news.nationalgeographic.com/news/2005/09/0916_050916_timetravel_2.html) that a wormhole mouth would weigh a 100 million solar masses, is that right? Wouldn't the exotic matter threading the wormhole negate this massive weight? Or at least bring it down to significantly?

That article is the only place that I've ever read about the weight of a wormhole mouth, but I would think that exotic matter could be used to negate the positive mass of the mouths; otherwise, the mouths would collapse in on themselves and create event horizons, right?

The concept of "holding" the mouth of a wormhole open comes from negative energy solutions that MIGHT lead to the desired effect. I don't think there's any way assign a mass to the wormhole that isn't the mass assigned to the black hole in general. Whatever the mouth/throat of a wormhole would require to say "open" is a theoretical negative mass.

When you talk about holding something that may or may not exist open with something that may or may not exist, it's very hard to give answers that aren't fundamentally misleading.

 

[TheTraveler]

The concept of "holding" the mouth of a wormhole open comes from negative energy solutions that MIGHT lead to the desired effect. I don't think there's any way assign a mass to the wormhole that isn't the mass assigned to the black hole in general. Whatever the mouth/throat of a wormhole would require to say "open" is a theoretical negative mass.

When you talk about holding something that may or may not exist open with something that may or may not exist, it's very hard to give answers that aren't fundamentally misleading.

Don't worry, I totally understand we are treading more into sci-fi and theory, rather than textbook physics.

The reason I ask about the weight is because one of Morris-Thorne's requirements for a transverable wormhole would be for it to provide a smooth ride. With a mouth only having a surface area of a few meters, but having the mass of a massive black hole, I would think the tidal forces would rip a traveler apart. And that's assuming it wouldn't start to create an inescapable event horizon, whose absence is also a Morris-Thorne requirement.

I was thinking that exotic matter (along with providing the tension to hold the mouths open) was also needed to negate this massive gravity (i.e., negative mass would counter balance the massive positive energy/mass). This is entirely conjecture on my part though. I haven't seen any other explanation of how to prevent the wormhole from just collapsing into a black hole, and exotic matter is the only thing that I can see mentioned anywhere that would prevent this.

 

[Nabeshin]

I'm not sure about the whole mass issue. It is not even entirely clear to me if it is meaningful to assign a mass to a wormhole. A wormhole is a property of the spacetime geometry, specifically an irregularity in its topology. So, at the most basic level it doesn't make much sense to talk about the mass of a topological feature.

So I'm really confused as to what Gott means when he references such a specific mass in that article. I have a hunch that he's not talking about a physical mass, but rather relating something deeper into a unit the public can get their heads around (or not, since it's still huge).

As far as tidal forces are concerned, it's quite trivial, within the framework of GR, to construct a wormhole which has identically zero tidal forces. Whether or not these solutions resemble at all the kind of quantum wormholes Wheeler predicted is another matter entirely...

 

[Nicodemus]

I'm not sure about the whole mass issue. It is not even entirely clear to me if it is meaningful to assign a mass to a wormhole. A wormhole is a property of the spacetime geometry, specifically an irregularity in its topology. So, at the most basic level it doesn't make much sense to talk about the mass of a topological feature.

So I'm really confused as to what Gott means when he references such a specific mass in that article. I have a hunch that he's not talking about a physical mass, but rather relating something deeper into a unit the public can get their heads around (or not, since it's still huge).

As far as tidal forces are concerned, it's quite trivial, within the framework of GR, to construct a wormhole which has identically zero tidal forces. Whether or not these solutions resemble at all the kind of quantum wormholes Wheeler predicted is another matter entirely...

Yeah, the only mass number I know of that you associate with a black hole is the mass within the event horizon. Anything else is... who the hell knows? Still, I'd like to see how Gott arrived at a number at all, unless it's just what you say: a teaching tool.

 

[TheTraveler]

A wormhole is a property of the spacetime geometry, specifically an irregularity in its topology. So, at the most basic level it doesn't make much sense to talk about the mass of a topological feature.

I see, so a wormhole is better described as a part of spacetime itself. I should stop thinking of them as separate objects, like what black holes and stars are.

I think all is clear to me now, thank you so much for all your help!

 

[Nicodemus]

I see, so a wormhole is better described as a part of spacetime itself. I should stop thinking of them as separate objects, like what black holes and stars are.

I think all is clear to me now, thank you so much for all your help!

Black holes, at least from the event horizon inward, are also a deformation in spacetime, one that becomes most extreme at the singularity. There is no way for modern physics, AFAIK, to define anything which relies on information beyond the event horizon of a black hole. Any theory which could "slice" a part of what's inside the event horizon would be amazing, but may be too much to ask even for a theory of quantum gravity.

 

[stevebd1]

One of the supposed problems for wormholes to exist is radiation feedback and there would have to be a way of protecting the wormhole throats from allowing a loop of EM or virtual particles. One very tenuous way of doing this is to consider the weak singularity at the Cauchy horizon of a rotating/charged black hole, where the curvature singularity increases like a Dirac delta function, this is like a pinch in spacetime where EM and VP might be stopped/collected whereas a spaceship which is robust enough would be allowed to pass through. If the black hole was a^2+Q^2=M^2 then the inner Cauchy horizon and outer horizon would merge, while in some cases, it's considered that both event horizons would disappear, they would actually become degenerate, only when a^2+Q^2>M^2 do they disappear, this may mean that the Dirac delta function is still in effect and EM and VP would be prevented from entering the wormhole throat. The degenerate horizon might also have the appearance of a regular horizon but allow passage back and forth. For this to work as a means of travelling, you would need the exact same arrangement for another Kerr-Newman black hole elsewhere.

 

[Nabeshin]

One of the supposed problems for wormholes to exist is radiation feedback and there would have to be a way of protecting the wormhole throats from allowing a loop of EM or virtual particles.

Isn't this only a problem for wormholes which also act as time machines? That is, the time delay between the two mouths is greater than the spatial separation between them?

 

[stevebd1]

Isn't this only a problem for wormholes which also act as time machines? That is, the time delay between the two mouths is greater than the spatial separation between them?

You're right. I suppose the above only applies to time travel wormholes.