Talk:Wormhole

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[edit] Wormholes but not physics

These pages consist of about 0.1% physics (the Schwartschild wormhole) and 99.9% fantasy fiction. The completely imaginary wormholes of TV space operas need to be clearly distinguished from the nonphysical solutions to classical gravitational field equations that are actually part of physics.

Further, the physics, as it is presented, is not even necessarily correct on the page. For example, the argument that wormholes do not allow faster than light travel is flawed, as it does place you in another part of the universe at a distance that is forbidden based on the time it took by a world line. Such possibilities do create causal impossibilities according to special relativity. Further, wormholes are not two dimentional circles, as they would be if we lived in a 2D universe, but rather, to extend the analogy illustrated in the first image, it would have to be a sphere connecting two space-time points by a fifth dimention (past the three space dimentions and the time dimention). I'm not saying that I know all of the physics behind a wormhole, but I am saying that none of the people who wrote this page (with the exception of the topology material) know it either. I would prefer for someone with actual knowledge of the physics behind it (i.e. have taken a general relativity course in college or preferably grad school) to come and fix the page.

In Argument: Not nessearily, the wormhole is a portion of Theorectical Physics which is at this present time being researched and studied. As you say this article does contain mostly fiction, but most of what is here complies with the theorectical physics. While the wormholes of all TV shows and operas are in fact fictional, that is not to say that the "wormhole" is 99.9% fiction and .1% truth. Also for some of those shows which you speak of (e.g. Stargate SG-1) they have done a considerable amount of research surrounding the Subject of Theorectcal Physics, and from this chose the mode of Space Travel which was most practical. THIS IS NOT TO SAY THAT WHAT YOU SEE ON STARGATE SG-1 IS REAL, This is only to say that they did a considerable amount of research into this before going around making things up (obviously there is most likely no 'Orie' and/or 'Jafaah' in the Universe). I do however agree with you in the fact that they should probably be seperated and clearly labled as FICTIONAL if they have not been proved or refuted. Please let me know what you think of my counter argument at lespaulYX@yahoo.com. Thanks

  • Well the section is labeled "wormholes in fiction" - though it might not have been when you posted the comments - which should be enough to make the reader realize that they shouldn't take what it say as the way nature works (in case the Fi part of SciFi wasn't enough). At this point the fiction section takes up about as much space as the science section, so maybe it's time to split it off. Koweja 03:31, 6 June 2006 (UTC)

In argument to the argument: The research done on television shows is incomplete at best, and representing it as fact in any way is misleading. The research done on most shows (including stargate) is just into jargon in order to make it sound imposing. There is no reason to believe that anything presented is based in reality.

[edit] Wormhole as an IT term

Wormhole also refers, by analogy, to IT applications in network concentrators for example. Data or data packets enter the concentrator and to prevent blocking and data loss the packets (with header bits) can move transversally through the columns as well as along the lines. —The preceding unsigned comment was added by 62.175.67.195 (talk • contribs) on 08:12, 20 May 2004.

[edit] Additional physicist

I see Einstein and Rosen mentioned, but wasn't there a third guy? Podolsky, or something? Or was that a separate but related conjencture? Amayzes 06:13, 2005 Apr 16 (UTC)

You're thinking of the EPR Paradox. --khaosworks 06:26, 16 Apr 2005 (UTC)

[edit] Added some more info

I have expanded the article a bit. Although there are many different kinds, the empasis is still on traversable wormholes. It would be great of someone could cover the other types. MadIce 14:21, 8 May 2005 (UTC)

[edit] Various fixes

Could somebody look at this and please make sure I've retained its meaning? It wasn't very clear to begin with:

== Traversable wormholes ==

Lorentzian traversable wormholes would allow travel to one part of the universe very quickly as well as from one universe to another. Because wormholes not only connect spatial locations they would also allow time travel.

Jayc 03:13, May 13, 2005 (UTC)

[edit] Attempt to explain the idea a bit better

I've tried to explain the idea a bit better. It doesn't "sound well", but it should get the point across.

== Traversable wormholes ==

Lorentzian traversable wormholes would allow travel from one part of the universe to another part of that same universe very quickly or would allow travel from one universe to another universe. Because wormholes not only connect spatial locations they would also allow time travel. MadIce 00:33, 16 May 2005 (UTC)

[edit] Merger with 'wormhole metrics'

Sounds like a good idea. ---Mpatel (talk) 17:36, August 30, 2005 (UTC)

[edit] Wormholes and naming: apples vs books

I think the origin of "wormhole" is probably more to do with bookworms than apple-worms (although I know that people like using apples as examples as a Newton in-joke, eg the cover of MTW's "Gravitation"). The "distance between opposing the pages of a book, when the pages are pressed together" analogy crops up in at least one ancient sci-fi short story, probably an HG Wells jobby.

I also liked the alternative name that appeared in an episode of Sliders, where they arrive in a parallel universe where these things are instead referred to as "mouseholes".

[edit] The light cone

Don't wormholes contradict the light cone on the Lightspeed page? Since a wormhole would allow you to go to a point outside the cone anyway --213.118.112.4 15:37, 30 October 2005 (UTC)

You would have travel a distance within the light cone to a location that only appears to be out of the light cone. If you were to draw the cone so it also moves through the wormhole you would see it is within reach of the light cone. —The preceding unsigned comment was added by 66.213.78.130 (talk • contribs) on 19:34, 24 May 2006.

[edit] treading on sacred ground and request a link

It is my contention that Traversable Wormholes exist on earth and that strange creatures, perhaps made of exotic matter or anti-matter, such as large unkown hairy humanoids and some lake monsters, are able to utilize them for passage to other universes (dimensions). Wormholes then are not just exotic theory, but have a practical basis and use. I assure you this is not a joke. Please add this link in external links, request to the page founder, :

http://www.beckjord.com/wormholesinuse

FWIW, it is my theory that humans who engage in the out of body experience, OOBE, may in fact be going through a workhole to another universe and then back. The sam may apply to certain realistic dreams,and the "dreams" may be a record of an actual mental voyage.


Thanks,

beckjordBeckjord 08:13, 17 December 2005 (UTC)

[edit] Confused terminology

I'm curing two problems with terminology in this article. First, the terms 'wormhole' and Einstein-Rosen bridge are not synonymous in ordinary usage. The ER bridge is the Schwarzschild wormhole, but not all wormholes are of this type. Second, the ER bridge received its name from the 1935 paper by A. Einstein and N. Rosen, "The particle problem in the general theory of relativity", Phys. Rev. 48, 73-77 (1935). This has nothing to do with Podolsky or the EPR paper, and ER bridges are never, in my experience, referred to as EPR bridges. Physicist 19:22, 21 December 2005 (UTC)

[edit] Merge from Alice Universe

Alice universe should be merged into this page or deleted. It is not notable enough to have its own page.

I disagree. If we can have entries for, say, pokemon characters, then we can certainly have an entry for Alice universes. Think of Alice universes as fancruft for physicists. Physicist 23:09, 22 January 2006 (UTC)
That is a non sequitur. Notable pokemon characters are more notable than Alice Universe. Non-notable pokemon characters should not have their own page.. can you name one? Zargulon 03:12, 23 January 2006 (UTC)
It's not a non sequitur. Your second sentence indicates that you are disagreeing with one of my premises, not with my mode of reasoning. And no, I can't name any pokemon characters: none of them is notable. Physicist 15:04, 23 January 2006 (UTC)
"If we can have entries for, say, pokemon characters, then we can certainly have an entry for Alice universes" is a classic non sequitur. I also happen to disagree with your premise that no pokemon characters are notable (although they don't interest me personally), and I strongly disagree with your implication that pokemon characters' non-notability follows from the fact that you can't name any! I can't think of any reasonable definition of notability which sets Pikachu as less notable than Alice Universe. If you can, please don't hesitate to share it. Zargulon 15:14, 23 January 2006 (UTC)
It's not a non sequitur, classic or otherwise. You are refusing to recognize all of the premises which I implied (or tried to imply) with my statement. I'm not sure whether you really found my remarks confusing because you were unable to infer my premises, or whether you are simply feigning stupidity for the sake of argument. In any event, this argument doesn't further our efforts to improve Wikipedia. Let's focus on that. Notable means "worthy of notice; remarkable; memorable; noted or distinguished", according to the Wictionary. Alice universes appear to me to be "worthy of notice" because they arise naturally as soon as one begins thinking about field theories in curved spacetimes; in a sense, you can't help noticing them. On the other hand, pokemon seems to me to be some element of popular culture; as such, I don't see why it's worthy of notice. However, I'm willing to accept that perhaps it is. I didn't mean to imply "that pokemon characters' non-notability follows from the fact that [I] can't name any"; that was an incorrect inference. Physicist 17:00, 23 January 2006 (UTC)
I accept that you did not consciously make a non sequitur, and that you believed you somehow implied premises which in turn gave integrity to your opening statement. I also promise that any actual stupidity on my part is completely natural and unfeigned. I accept your definition of notability, but like most wikipedians I acknowledge degrees of notability, and I totally stand by my opinion that, due to their degrees of notability, Pikachu should have its own article whereas Alice Universe should not. That doesn't mean I think that Alice Universe is so non-notable that it should not be mentioned in wikipedia at all, nor have I suggested that. I didn't understand your sentence "pokemon seems to me to be some element of popular culture; as such, I don't see why it's worthy of notice".. was that a) just an opinion (which is fine), b) an argument which is alleged to follow from our definition of "notable" (if so, it appears to me like a non sequitur) or c) an argument which follows from other implied premises (in which case, what are they?) Zargulon 18:53, 23 January 2006 (UTC)

Changing merge to Non-orientable wormhole. Zargulon 16:40, 26 January 2006 (UTC)

[edit] Citation of this page

Just letting contributors to this article know that a page on the BBC website here about their new documentary series Time links to this page as an explanation of wormholes. --RobertG ♬ talk 12:46, 28 February 2006 (UTC)

[edit] Explain wormhole metrics

I was wondering if it would be a good idea for someone to explain the formulae under the heading Wormhole Metrics. I dont understand it and was wanting to. I was thinking that other people may be thinking the same thing. Stwalkerster 21:37, 24 March 2006 (UTC)

This is (in principle) explained in Kruskal-Szekeres coordinates, but the present state of this article is not very illuminating. Alain Riazuelo 23:18, 9 July 2006 (UTC)

[edit] Why...

Can someone explain why Michio Kaku is not mentioned ? His site is www.mkaku.org and it has a LOT of material concerning wormholes. Martial Law 21:19, 13 April 2006 (UTC) :)

His field of expertise seems to be string theory. He's talked about wormholes in popular-science type presentations, but he's also talked about many other things. --Christopher Thomas 19:08, 14 April 2006 (UTC)

[edit] Split the Sci and the Fi?

Right the Wormholes in Fiction section is about the same size as the entire rest of the article. Would anybody object to me creating a separate Wormholes in Fiction page and moving that part of the page over? It would also make it easier to organize and clean up the information. Koweja 03:34, 6 June 2006 (UTC)

This sounds reasonable, though a more MoS-compliant title would just be Wormholes in fiction (capitals only at the front or for proper nouns). I'd also suggest keeping a bulleted list of a few noteworthy examples in the main article, with a caveat in comments that new entries should be added to the fiction article]]. --Christopher Thomas 03:58, 6 June 2006 (UTC)

[edit] 2D diagram doen't match up with 3D reality

I don't understand the diagram, it shows a 2D space, but how does that apply to 3D space? And if a wormhole is flat, with the 'mouth' on one face, then what is one the opposite face?

[edit] Concerning the THROAT

This is something about that i read in a book called LIFE AFTER DEATH by MARY T BROWNE. Well she talk about the soul of the person after dying seems to be travelling through a tunnel of some sort. At the end of the tunnel live the sould of the people. Well i was just wondering, could this be another type place in the universe where the souls may be living? And if yes, then there's a worm hole connectin the earth to that place?

This question is well beyond the realm of scientific fact. --Fastfission 23:42, 11 September 2006 (UTC)

[edit] recent edit explanation

The Scwharzschild wormhole isn't traversible, but the event horizon of a black hole is not necessarily a barrier to a black hole /white hole sort of wormhole. Just as one must always fall into a black hole, one must always fall out of a black hole. Thus one would not get "trapped in the middle" as the article stated. Pervect 23:43, 27 August 2006 (UTC)

Are you sure this is correct? One of the external links[1] had a qualitative overview of the problem (as far as I can figure out, it only looks like a white hole/black hole pair at one instant in time, and ends up looking like a pair of black holes or a pair of white holes at other times). My math isn't good enough to check the claims directly. --Christopher Thomas 20:15, 27 August 2006 (UTC)
For what I actually wrote in the main article, see for instance http://arxiv.org/PS_cache/physics/pdf/0505/0505108.pdf page 4. Thorne was aware of the Einstein-Rosen bridge, and it's non-traversibility. After being contacted by Sagan, Thorne realized that exotic matter could be used to hold open the throat of a Schwarzschild wormhole and make it traversable.
Most wormholes actually don't have event horizons. Looking at the metric in the above URL, it appears that Thorne's metric doesn't have an event horizon. I don't see any logical impossibility in having a "one-way" wormhole with an event horizon, and someone told me once that such wormholes existed and were discussed in Visser's "Lorentzian wormholes". Unfortunately I don't have this particular book so I'm relying on hearsay and logic. This probably wouldn't be good enough to put in the main article, but I see that my claims in the main article were a little more modest.
I don't think there's a real major discrepancy with what I read in Hamilton's url, which is I assume your reference. He points out that there would be some unpleasant thermodynamic consequences to white holes. I agree that they would be unpleasant, but I wouldn't agree that this makes them logically impossible.
A more important practical issue is that the geometry caused by a gravitational collapse wouldn't actually be a Schwarzschild black hole. It would be a BKL singularity. The Schwarzschild geometry isn't stable in the interior region of a black hole formed by gravitational collapse. —The preceding unsigned comment was added by Pervect (talk • contribs) on 23:48, 27 August 2006.
Scroll down to the section titled "impossible to pass through the wormhole", for the commentary. I'm not convinced the page is accurate - as I see where the "one-way" model comes from, and don't see a qualitative reason for it to be wrong - but I'd certainly hope that the reference page checked the math. I agree that the wormholes end up being non-traversible for other reasons (pinching off instantly and not forming from stellar collapses), but the statement that such a wormhole _could_ be traversible if stabilization occurs inside the horizon should still be verified. I've taken a careful look at the reference you cite above, and it doesn't seem to address this concern (instead it just carefully constructs the geometries involved).
I agree that it should be possible to use exotic matter to stabilize a wormhole in such a way as to not have a horizon forming at all (by putting the shell of exotic matter outside the Schwarzschild radius), but that's a different issue. --Christopher Thomas 01:08, 28 August 2006 (UTC)


I agree now that that's what your reference says. Thus in some sense it's "fair game" for citation. However, I don't think that the explanation makes any sense. A particle transversing the wormhole experiences no singularity, yet the article would have us believe that the worldline of a traversing particle, with the "arrow of time" drawn in, looks like this ----><-----, two one-way roads meeting at a common point. This topology just doesn't make any sense. There is nothing like a singularity to make any one point "special" such that it should be the points where the worldlines collide. Worldlines suddenly stopping for no reason don't make any sense either. It makes much more sense to me to assume that the manifold isn't time-orientable. Not all manifolds allow a consistent assignment of the direction of time. To quote Wald "Thus non-time orientable spacetimes have the physically pathological property that we cannot consistently distinguish between the notions of going "forward in time" as opposed to "backward in time". While I have references that say that non-time orientable manifolds exist in GR, I don't have a reference to say specifically that the manifold under discussion is an example of such. We don't even have a metric at this point. Of course the reference doesn't offer us a proof that the manifold in question is time orientable either. Pervect 05:32, 28 August 2006 (UTC)
The reference you cited proves metrics. It should be possible to tune the Morris-Thorne wormhole metric, which represents the case of a wormhole stabilized with exotic matter, to an arbitrary throat radius (greater than and less than the Schwarzschild radius). I don't have the math to trace timelike geodesics in the resulting system, but we could always ping User:Linas, User:Salsb, or one of the other GR types at WikiProject Physics to sanity-check it for us (or you could check it, as you seem to be reasonably familiar with the subject). If the statements on the web page are demonstrably incorrect, I'm more than happy to keep the statements as you've laid them out even without an external citation. I actually think you're probably right; I'm just hesitant to endorse the change as long as the conflict with a reference exists. --Christopher Thomas 06:10, 28 August 2006 (UTC)

I'm going back to zero level indent for my convenience...

The note after reference 12 comes close to giving us a metric, but unfortunately the potential function Φ isn't defined in terms of coordinates. My first impulse is to trace out the null radial geodesics via

e^{2 \Phi} dt^2 = \frac{dr^2}{1-\frac{{b_0}^2}{r^2}}

I would guess b0 is a constant, but I'm pretty sure Φ is a function.

Possibly, we might be able to work with just what we've got, though. The term on the left hand side will always be positive. So will the term on the right hand side if |r|<b0. When r=b0, we have an event horizon, light never reaches r=b0 in a finte amount of coordinate time. If we imagine light coming in one horizon, it must either "bounce" somewhere (for instance at r=0) and since it reverses direction, leave through the same horizon it entered by (impossible), or else it must continue on, and leave through the opposite horizon. There's no way for it to 'get stuck' that makes sense mathematically that I can see, i.e. one that satisfies the above equation. The equation was dervied just by setting the Lorentz interval to zero for a null geodesic. Pervect 07:22, 28 August 2006 (UTC)

Let me (hopefully) clarify a few things. A change to conformal time tc should allow us to write the metric as
ds^2 = \frac{1}{1-\frac{{b_0}^2}{r^2}} (dr^2 - dt_c^2)
where
dt_c= e^{-\Phi} \sqrt{\frac{1}{1-\frac{{b_0}^2}{r^2}}} dt
This makes the path of light "straight", as dr=dtc when we switch to conformal time.
Insisting that the second derivative always remains continuous leads to the argument that dr/dt should never change sign. However, due to the nature of our coordinate system, we expect that dr/dt will change sign when the particle passes through the origin even if it has a flat metric. Consider a radial photon in flat space. As it approaches the origin dr/dt < 0. At the origin dr/dt > 0. The second derivative is undefined at the origin. So we expect dr/dt to change sign at the origin.
If we assume for the sake of seeing what happens the photon never changes sign for dr/dt, even at the origin, it gets "reflected" back on its outgoing path. This is obviously wrong. So we expect the particle to change the sign of dr/dt at the origin, and nowhere else. This leads to the behavior I described, where the photon comes in from one event horizon and leaves through the other. The key points are that conformal time monotonically increases with coordinate time (in the region |r| < b0, dt>0 implies dtc > 0 ) and that the path of light is straight in conformal time. We can make both of these staments without knowing the details of Φ because eΦ is always positive. Pervect 20:24, 29 August 2006 (UTC) Pervect 21:48, 29 August 2006 (UTC)
This is sounding reasonable. The only thing that gives me pause is that it should be possible to define a coordinate system on the Morris-Thorne wormhole that doesn't have the photon reach r = 0, as the throat has nonzero radius. The author of the web page about wormholes has accepted corrections to the page in the past; perhaps ping him about this thread? --Christopher Thomas 01:30, 30 August 2006 (UTC)
I was going to suggest doing the analysis on the traversable wormhole on the webpage, but there isn't much point as it doesn't have a horzion. But the procedure to do it on the incomplete metric is the same. Basically because none of the metric coefficients is a function of \phi\,, assuming that \Phi\, isn't a function of \phi\, which I believe is correct, E_{\phi} \, should be constant. This means that for \theta = \pi/2\,, r^2 \frac{d\phi}{d\tau} should be constant, where \tau\, is proper time. Solving this together with the Lorentz interval being zero should give us the the needed two equations for finding a non-radial null geodesic.
I think that you make a reasonable suggestion in dropping the author of the webpage a note. I'll do so. Pervect 02:44, 30 August 2006 (UTC)
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