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we can see most of the science fiction stories, movies, and television serials use the concept of wormholes. Do wormholes really exist in this universe? I'm curious about it.

And also, what are the types of wormholes?

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    $\begingroup$ Many people are curious to know, but wormholes (if you are not talking about holes created by worms ;) ) haven't been observed. $\endgroup$
    – nwolijin
    Feb 9, 2021 at 7:36
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    $\begingroup$ @nwolijin haha :-) so, is that only a concept? $\endgroup$ Feb 9, 2021 at 7:39
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    $\begingroup$ at the moment it is just a theoretical construction. Btw, conditions for implementing it are rather strict. You may want to listen to this podcase: preposterousuniverse.com/podcast/2020/11/23/… $\endgroup$
    – nwolijin
    Feb 9, 2021 at 7:44
  • $\begingroup$ A simplistic explanation, also describes the different types: youtube.com/… $\endgroup$
    – LiefdeWen
    Feb 10, 2021 at 9:50
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    $\begingroup$ Something that most sci-fi stories leave out (or intentionally omit via literary license) is that a wormhole would possibly (probably?) exhibit many properties similar to a black hole (though altered or distorted), spaghettification seems likely, some type of event horizon/boundary where the laws of physics change or are indeterminate, etc., are possible. $\endgroup$ Feb 10, 2021 at 16:00

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General relativity asserts that certain configurations of spacetime, called wormholes, will satisfy the equations that govern spacetime and this is why they are part of mainstream physics. However, there are two qualifying observations:

  1. If at some time there are no wormholes anywhere, then it seems that none can form by any physical process of a type which could in principle be described by classical as opposed to quantum physics. I say "seems" here because this has not been proved in complete generality but it is certainly true in all configurations that one can reasonably expect to come about by natural processes.

  2. The mere existence of a wormhole does not necessarily imply that travel through the wormhole is possible, because of stability considerations (and some kinds of wormhole are not timelike anyway). The stability problem is of two kinds: the impact on the traveler of other stuff such as light passing into the wormhole, and the fact that their very presence (their mass) may cause the spacetime to distort in such a way as to seal the wormhole.

At the moment it is hard, therefore, to assert with any confidence that there really could be a traversable wormhole somewhere.

However one should add that when we bring in quantum physics then the range of possibilities becomes a lot richer. It seems now that one ought not to discount the possibility of wormholes, at least at microscopic scales, which is another way of saying that the structure of spacetime may be very complicated at the Planck scale. However this is not the kind of thing that ordinary people mean when they think about wormholes in science fiction scenarios.

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    $\begingroup$ Unicorns satisfy the equations that govern spacetime as well. Should that make them 'mainstream' in any way? I think the more general question is 'does spacetime exhibit any nontrivial topologies' and the answer is 'not that we have observed'. $\endgroup$ Feb 10, 2021 at 1:47
  • $\begingroup$ Just a note: Gibbons and Hawking seem to confirm that wormholes, within the context of purely classical General relativity can only be created in pairs: maths.ed.ac.uk/~v1ranick/papers/gibhaw2.pdf That doesn't necessarily negate your point of them not happening naturally though. $\endgroup$
    – R. Rankin
    Feb 10, 2021 at 3:38
  • $\begingroup$ Interesting some answers are saying wh can not be actively created, why is this?? Conservation or some idea which we typically like to hold on to? Seem it is a... G.R. Dynamical question as opposed to static, and with G.R. being complicated enough. $\endgroup$ Feb 10, 2021 at 5:20
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    $\begingroup$ @EelcoHoogendoorn Unicorns are an ill-defined phenomenon. Their original definition was simply "a beast with a single horn", something which certainly can and has existed and also could be readily created through either breeding or genetics. $\endgroup$ Feb 10, 2021 at 16:12
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Worm holes are the product of the fact that the differential equations for general relativity have (permit) closed loop solutions. This implies that at the very MOST, the very simple and neat equations allow, looped space and time. These things need a real interpretation which isn't easy. One is that, space gets so warped that it can loop as opposed to being flat, has to do with geometry, and Klein bottle type stuff. But I suppose this leads to unintuitive phenomena, like travelling one way, and ending up a larger distance away than what would seem possible via normal paths.

Similarly with time, I suppose, which is even harder to apply to reality, but would be forward temporal destination leading to past times. Some of these are paradoxical and some reject they could be possible.

On normal scales there is no way to get feedback to the issue. On small scales there are issues with difficulty in making observation again. So I would presume there is little actual evidence in either direction. Only correlation with common measurable phenomena with general relativity field equations. There is no reason necessarily to presume they follow such curves far beyond these regions. It could be that different phenomena emerge which if predictable require new formulations, which do not have such closed solutions.

It is interesting to note that NASA does research a warp drive. This drive would utilize warping space time, so that faster than light travel is achieved. But no holes are utilized, only the contraction of space. This requires the contraction of space, which brings the object closer then normal, allowing faster transit than what would normally be possible even at light speed travel. This method is much more realizable but not to a level that is actually useful for transporting anything yet. But no puncturing of space and time travel is done. No observable puncture has ever been discovered. Black holes could be an example if General Relativity stands, but if not it could be just an extremely massive planet/star thing.

If we think, to any one that did not know better, and thought the earth was flat, because everything locally is flat, it would be similarly odd, to see someone leave travelling one direction, and arrive from the other. So it is presumable that spatial punctures could exist, as well as finite closed space. Closed time seems a little more problematic. But I do not know of any evidence for punctured space. And it can not be known if such things which are solutions to the equations, follow reality.

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    $\begingroup$ "It is interesting to note that NASA does research a warp drive. This drive would utilize warping space time, so that faster than light travel is achieved." - FTL with a warp drive requires exotic matter with negative mass. $\endgroup$
    – Beefster
    Feb 11, 2021 at 17:31
  • $\begingroup$ Do not take out of context, the immediately following comments, to the effect that allow faster transit then light speed travel would allow $\endgroup$ Feb 12, 2021 at 11:27
  • $\begingroup$ The idea is light speed transit time non warped path, vs contracted path. With reguard to the curved space, FTL is not achieved. But otherwise FTL is achieved. $\endgroup$ Feb 12, 2021 at 11:29
  • $\begingroup$ Warp drive is only a theoretical concept. Most likely, we will only be able to achieve subluminal speeds even with a warp drive due to energy and mass requirements. FTL probably (as in 99.9999999999% chance) lives only in the realm of fiction, unfortunately. $\endgroup$
    – Beefster
    Feb 12, 2021 at 17:22
  • $\begingroup$ I do read some claims negative mass would be required to warp space for such drives, though I remain skeptical admit for now it does seem to be the consensus. $\endgroup$ Feb 12, 2021 at 18:00
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No, as far as we know there are no wormholes anywhere in the universe. In fact, we know of no realistic physical mechanism that would lead to the creation of a wormhole in nature.

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    $\begingroup$ I agree that we have no evidence of one actually existing, but the possibility of their existence is mathematically sound. We don't have a realistic physical mechanism that would lead to the singularity that existed prior to the big bang, and yet evidently such a thing did exist according to our calculations and mathematical models $\endgroup$
    – Kevin
    Feb 9, 2021 at 22:41
  • $\begingroup$ @KevinWells, In order for the possibility of the existence “mathematically sound”, we would need a mathematically sound way for them to come into existence, and we don’t. This is ver different from the Big Bang, where we have theorem that generically GR necessitates the existence of a singularity at the beginning and/ or end of time. Although we can’t discount the possibility of wormholes, their status as a possible exotic object is much less certain, then for example magnetic monopoles and cosmic strings, for which we at least have plausible formation scenarios. $\endgroup$
    – TimRias
    Feb 10, 2021 at 0:32
  • $\begingroup$ I'm not sure about your second sentence. Take two very large collections of matter that are maximally entangled with each other and allow them separately to collapse. A lot of people expect this to give us two black holes connected by a wormhole. $\endgroup$
    – d_b
    Feb 10, 2021 at 5:20
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    $\begingroup$ The universe has no limits, isn't it? Maybe there will be wormholes far away from our galaxy. $\endgroup$ Feb 10, 2021 at 8:39
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    $\begingroup$ @KevinWells Technically, the universe could also have formed with primordial invisible purple unicorns scattered about. At this point, we have as much reason to believe in the existence of IPUs as we have in the existence of wormholes. Neither can be excluded as a possibility, but there is essentially no theoretical or observational reason to think that they should exist. $\endgroup$
    – TimRias
    Feb 10, 2021 at 16:50
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Whether or not wormholes exist is an empirical question. So far, the answer seems to be "No", because we simply have not observed any. However, the Universe is very, very big and there is no reason a wormhole might necessarily be easy to spot in all possible ways they could occur. So this is not a really strong "no".

It is sometimes claimed that wormholes are "predicted to exist" by general relativity. This is not actually what it says. It would be better to say that what it says is that they are permitted to exist, in that the existence of one would not in any way, shape, or form contradict or invalidate the theory of general relativity. However, general relativity alone also offers no physical process by which a wormhole could form starting only from things we know to exist, such as ordinary matter and radiation. This would mean that if any wormholes exist, they had to have either been primordial - formed with the creation of the Universe in the Big Bang - or they would have to arise through some other process on whose existence general relativity is silent.

Note that, again, in this last comment, that also doesn't mean general relativity forbids such processes. Only that, given what we know, their existence is not implied by the theory.

In the end, the real answer is "maybe". And it likely will be that way for a quite long time, until we gather the right empirical evidence either to observe an actual wormhole, to rule them and/or their physical processes out, or to gather the empirical evidence needed to substantiate a post-standard model theory from which we can then infer the possible (non)existence of wormholes. And in that regard, we likely will need a moment of serendipity, because the methods we know already to probe post-SM (which I define here as meaning "our existing understanding of the physics of our Universe") physics are stupendously out of reach technologically, such as particle accelerators of dimensions equal to interstellar distances, so that, without wormholes :) they would necessarily take thousands or millions of years to build.

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  • $\begingroup$ I think gr and observation, imply worm holes. There are observed massive objects which would have worm holes, though that is a different question and interesting. I don't pretend to have done the calculations. $\endgroup$ Feb 10, 2021 at 5:09
  • $\begingroup$ @The_Sympathizer thank you very much... a very clear explanation. :-) $\endgroup$ Feb 10, 2021 at 8:03
  • $\begingroup$ Okay nobody answer my comment, but seems like from purely geometrical argument, any looped Surface, isn't contimously deformable to a flat surface. And presumable vice versa. There would need to be some puncturing process, where the one type of topological manifold is punctured and a hole loop is created. $\endgroup$ Feb 10, 2021 at 23:38
  • $\begingroup$ So basically there is no continuous geometrical way to get from one solution manifold to the other. But if we think of Newtonian gravity, you have closed elliptical orbits and then hyperbolic ones which do not have finite length. So it would seem tempting to presume you could have warped space until some point it is metaphorically captured, and a loop is created. $\endgroup$ Feb 10, 2021 at 23:46
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There are considerable theoretical objections to the formation of a wormhole by any process of gravitational collapse. Such a process requires that the topology of the universe change, which is sort of like cutting or gluing spacetime. General relativity loses its predictive power in these situations. That doesn't mean that it can't happen, but it does mean that we would need some other theory of physics to describe it. Many such scenarios also require exotic matter of types that don't actually seem to exist in our universe. These issues are summarized in theorems on topology change by Geroch and Tipler.

Empirically, we do see objects that act like black holes in our universe, including very impressive agreement with theory for black hole mergers are observed in gravitational wave astronomy. This lends support to the theoretical arguments that runaway gravitational collapse produces black holes, not other exotic objects such as naked singularities or wormholes.

The theoretical arguments are classical, so they don't prevent topology change at the microscopic scale in the early universe, where quantum mechanics comes into play. We don't have a theory of quantum gravity, so we don't know. It's conceivable that there are relic microscopic wormholes in our universe right now.

A wormhole can't be traversible without exotic matter inside it. Therefore if there are wormholes in our universe, they probably aren't traversible.

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    $\begingroup$ A wormhole can't be traversible without exotic matter inside it. Oh yes they can, with the help of quantum entanglement. $\endgroup$ Feb 10, 2021 at 11:17
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Short answer: Nobody knows.

Longer one =>

  • Theoreticians have constructed a "traversable wormhole", a wormhole which does not need a negative energy for being stable. Wormhole sides are quantum mechanically connected, like in quantum teleportation. So at least, physicality of wormholes is now one step-closer for us.

  • Scientists are actively inventing methods for wormhole detection. This wormhole detection method is based on the fact that wormhole could induce subtle star -near wormhole throat- orbit perturbations in some way. This method talks that a wormhole will induce a phase modulation in an electromagnetic field passing-by, which can be detected by laser interferometers. But this is of course a very challenging project, due to noise and elimination of unnecessary gravitational waves effect. Scope is bigger than a LIGO project. But it is viable.

  • I'm not a theoretical physicist, but as I've heard, from theoretical physics perspective a wormhole is very hardly distinguishable from a black-hole. So IF wormhole(s) do exists, then we aren't sure anymore - Is there a black-hole or a wormhole in our Milky Way galaxy center?

  • And finally, it depends on how we define what is "a wormhole". If, for example I would define a wormhole as "A quantum channel where quantum information can be teleported from one end to the other" (albeit no faster than light-speed transport is permitted here). Then, such quantum-mechanical wormholes are already proven to exist and tested. For example, here quantum information was teleported over 143 km distance.

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    $\begingroup$ Ok but please do not call quantum teleportation "wormhole" or invite others to do so; it will only lead to confusion. Also, note that in quantum teleportation information is not transmitted by a quantum channel alone; it involves an entangled pair and a classical channel. The classical channel is completely ordinary classical communication. $\endgroup$ Feb 9, 2021 at 16:07
  • $\begingroup$ Quantum teleportation is a very important step, because it is somewhat involved in the traversable wormholes, i.e. throats of traversable wormhole are in a quantum connection. So without quantum teleportation and similar,- we'll not grasp traversable wormhole. I know about classical channel involved. Still this does not make an overall communication in a quantum teleportation a "classical", because it still involves a quantum channel too. So quantum teleportation has nothing to do with classical communication and is solely a quantum mechanical effect. $\endgroup$ Feb 9, 2021 at 16:13
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    $\begingroup$ @AndrewSteane Response to your comment above While it's just a conjecture at this point ER=EPR is extremely intriguing, and there does seem some backup to it. Check out this Stanford Lecture: youtube.com/watch?v=OBPpRqxY8Uw $\endgroup$
    – R. Rankin
    Feb 10, 2021 at 3:42
  • $\begingroup$ @R.Rankin thanks for this link which will certainly be informative for readers. My original comment was based on the following observation. I have performed quantum teleportation experiments in my lab, and spacetime is entirely ordinary in my lab. The same can be said for all the other quantum teleportation experiments. They neither involve nor require unusual topology of spacetime, nor extremes of energy density or anything like that. $\endgroup$ Feb 10, 2021 at 11:27
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    $\begingroup$ @AndrewSteane I don't think the point is to imply there are wormholes linking particles, but rather that the particles themselves might be described as such. Here's that paper by Hawking: maths.ed.ac.uk/~v1ranick/papers/gibhaw2.pdf $\endgroup$
    – R. Rankin
    May 20, 2021 at 20:09
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Wormholes presently is a theoretical hypothesis which arises from general relativity. To this date, there is no concrete observational data or experimental evidence in support for existence of wormholes. Wormhole is like bridge in fabric of spacetime which connects two distant regions.

There are different types of hypothetical and thought wormholes like: Einstein-Rosen Bridge, which describes that blackhole in our universe is connected to a parallel universe in which there is white-hole which spews everything out which fell in blackhole

String-Theory based wormholes, which describe that if string theory is correct description of our universe, then there are already natural wormholes kept open bycosmic strings, waiting to be discovered.

Man-made/Artificial wormholes, which could be made by humans. One possible way could be by creating exotic matter, which has negative gravitational mass, so it could repel things, and keep wormholes open.

These theories and ideas are indeed very wild which however are still unproven or unaccpeted to this date.

There are very strong statements in against existence of wormholes. Many physicists say that opening and traversing a wormhole could break several physics laws. First and foremost is that object traversing the wormhole in fact could travel faster than light which is not possible according to special theory of relativity. It could also create time travel paradoxes, or break casual structure of universe. So, existence of wormhole looks bleak according to our current theories.

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  • $\begingroup$ That is true of traversable wormholes $\endgroup$
    – R. Rankin
    May 20, 2021 at 20:10
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A huge deal in physics going on now is the realization of "ER == EPR". If this turns out to be true, then a wormhole can be created by taking two sets of entangled particles (every particle in A has an entangled partner in B) and collapsing both of them to black holes.

Leonard Suskind has given talks going over this in some detail, including the extent to which the interior can be probed.

By this mechanism, you can't make a sci-fi trope doorway to another part of the universe. And it would be exceedingly difficult to make an actual macroscopic wormhole at all, with which you can do the exact analogy of quantum teleportation (as explained by Leonard), requiring classical communication as well in order to teleport the quantum state through the wormhole.

But, if true, the mechanism exists in a simmering sense, under the scenes and is responsible for the emergence of GR and maybe spacetime itself from more fundamental QM fields. Think of it like "virtual particles" make electric and magnetic forces work, but don't require actual photons to materialize.

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As many answers point out, we don't know.

Yet, recently wormholes became a bit more likely. Indeed it has been discovered that wormholes can be built, as a solution of Einstein-Dirac-Maxwell gravity, in 4D without requiring exotic matter. The key insight with respect to the past has been inserting Dirac fermions (e.g. electron, quarks, etc.).

What does this result teach us? It teach that solid no-go theorems are very hard to build, since there are many ways to add new game changing elements to an existing theory. Also many theorems work with simplified assumptions (e.g. a theory with no fermions), which are often too simple to describe our universe.

So yes, wormholes may very well exists, time will tell!

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  • $\begingroup$ Wormhole could be made but main thing is to make it sustainable which is major problem. Many ideas like exotic matter is proposed which remains a pipe dream. $\endgroup$ Jan 23 at 4:04

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