The article may sound like promotion for some TV-series but this is not related to experiments done in the Hawkins National Laboratory in the 80s.
As I understand it, this mirror world would be colder than our own and this would affect nucleosynthesis in the early universe. There would be significantly more helium and less heavier particles. Because the mirror universe is connected to our universe trough gravity, we would definitely notice is dark matter stars and planets would go buy. Our universe would have more dense points of matter and the mirror universe would have more light gas clouds circling roughly at the same area as galaxies in our world.
Why do you think any of that? A hotter early universe would produce more helium, not less, and at the cost of hydrogen, not heavy elements. Not only were heavy elements effectively not produced by the big bang but even now make up an utterly insignificant portion of the universe.
Maybe I'm wrong. I'm just referring to what others have said written about this mirror universe theory. I'm not a particle physicist nor do I have original ideas about this subject.
Here is a paper from 2000 "The Early Mirror Universe: Inflation, Baryogenesis, Nucleosynthesis and Dark Matter"
https://arxiv.org/abs/hep-ph/0008105
Is the time difference between the neutron experiment results due to time dilation? One of them had the neutrons moving at high speed, I.e. In a particle beam.
No. Well, sort of. The time difference has to do with how you store free neutrons. Different conditions suppress, to varying extents, the possible energy states of the vacuum field.
Just as in the Casimir experiment it was demonstrated that opposed conductive plates are attracted with a force that results from the suppression of vacuum energy states between them, so must the decay of the neutron be modulated by the vacuum field.
If you contrive the storage system to suppress the vacuum energy to a greater extent, the field will interact less with free neutrons and they will live a little longer. Likewise, the more possible energy states, the shorter they live.
This effect is apparent because the free neutron is quite unstable and short-lived. It is readily affected by the particle-antiparticle pairs that are always popping into and out of existence in the vacuum.
Protons, which are very stable and last a long time, show the same effect, but you would be long dead by the time you observed it. So not a practical experiment.
Why does a radioactive element decay at a particular time? Why is it random? Why is Schroedinger's cat a superposition of alive/dead with no way of predicting which one until you observe it and collapse the wave equation?
The answer to all of these is the same. The background state of the universe is chaotic. It visibly affects things that are unstable, while not having much effect on things that are stable.
The faster something is moving, the more mass it has. The more mass, the less it is affected by the vacuum field. This is the mechanism of time dilation. Increased mass, decreased size, increased density, surrounded by mass, all of these contrive to suppress the interaction of the vacuum field with an object by limiting the possible states it can occupy.
The outcome looks to us like order, but it's not. Everything is randomness and chaos.
Newton's laws are approximations because they apply simple math to chaos. Likewise, general relativity is a geometric theory applied to a chaotic universe. It's a good approximation of what we see, but it's only an approximation. No geometric theory can explain something that is fundamentally chaotic.
The article mentions generating a beam from a reactor core, in which case for a 'Fast Neutron' reaction they would have 2 or 3 MeV, and be travelling at on the order of about 10% of the speed of light. That's fast, but far below the level at which any time dilation effect would be significant.
The most intriguing about stories such as this is that our own ignorance on topics such as e.g. dark matter will, at some point in the future, be something a fresh grad will look back on with bemusement - how could we not possibly have managed to discover [x] as it gradually comes to be seen as self evident? This is long since the case for Newtonian mechanics which are now the domain of secondary education, and is already starting to become the case for relativity for those of sufficient education.
It's kind of an interesting thought experiment to try to put yourself in the mindset of a people before the discovery of something and trying to imagine how you would have perceived the world and if you yourself might have conceived of such notions. For instance the idea that all objects fall at the same rate of speed is something that's oddly enough an extremely recent discovery. The tale of the apple falling on Newton's head dates to but 350 years ago. We, of today, are separated by then by little more than about 4 lifetimes.
It feels at times that science progresses through 1% genius and 99% creativity. Newton's gravity is, relative to the times, no more simple or complex than Einstein's gravity and undoubtedly whatever we may eventually find to be the source of dark matter. The tricky part is that the universe has this habit of requiring us to cast aside what we think we know and look towards paths that seem insane. A feather falls at the same rate of speed as a bowling ball? Time itself can move differently for people in the same location based upon their relative velocities? Physical distances can literally contract or expand again for people in the same location and again based on their relative velocities? Objects themselves can bend what seems to be emptiness and, in turn, bend light itself (to say nothing of also having an impact on time)? These ideas are mostly so difficult to develop not because of mathematical or technical problems, but because they sound insane. It's really quite a blessing for the inquisitive and creative that we seem to live in a universe that prides itself in as being as defiant of intuition as it possibly can.
I doubt that anything like that will become standard curriculum. Some conclusions and effects might become common knowglede, but the mechanisms and theory not.
It would have to be taught in high scholl, and even then not everyone have a complete high school knowledge. People don't generally know Newtonian mechanics unless they are physics undergrads or graduates. You need calculus to get it.
I would argue that Newton's theory was more complex because it required new math. Einstein didn't. The math was already there, and he managed to incept his idea without it. Riemannian geometry just simplified description. It's similar to Maxwell. He had electromagnetism in over 20 equations, then some lad whose name I forgot, made work and closed it down to four, that again 99 percent or more people don't know, though they govern nearly everything at our scale. Touch, vision and chemistry is described by them. I can come with only two things that are part of everyday life, that lie outside. Gravity, in the part that makes us stick to the planet, and atomic energy, though that's fast trasformed back to EM domain. Everything else seems to be far away, except for the fact they make things stable, but we don't harness it.
To me ingenuity and creativity are essentially the same. It's the abilty to have those insane ideas, perhaps genius is to pick important ones to ponder upon. I think we agree, that scientific breakthroughs seem to be based on making up grander picture, where what you physically see is some kind of special case of generally opposite rules. One of the greatest example is the idea that movement is generally self sustained, seems crazy here in the atmosphere, where the 1st theories said, that it requires force and work to keep going. Something we all experience.
Well, that's a long tought-chain. Hope someone's find it interesting.
When pondering progress in physics, do not underestimate the role of technological progress and the impact that has on experimental evidence, which are at the heart of all grest theories. These would not have been dreamt up without certain experimental data as the starring point for a new explanation.
Quantum mechanics required the weirdness of the blackbody radiation spectrum to spring to life. The special theory of relativity is based on the observation that the Maxwell equations are not Galileo invariant and the results of their strange Lorentz invariance can be observed. The general theory of relativity is baed on the realization that despite efforts to measure a difference, inertial mass and gravitational mass always have the same value.
It took time for these things to become measurable and to make people go "hmmm..." and think about nature in new ways. The answers are creative and genial, but they required starting points. And creating those takes time.
Barring the terrible style of the article, I think the concept of a mirror universe is not difficult to understand.
If we take our three spacial dimensions, and add another time dimension, then we can do a reflection at t=0 and this will produce a mirror object of everything from t>0 at t<0. (Note that in three dimensions, if we perform a reflection it is the same as a rotation when we add a fourth dimension, meaning we can do this "mechanically" if that is worth anything to you.)
This universe at t<0 looks exactly the same as our universe at t>0, except that you switch chirality (or left and right if you will). Now my toy example does not have exotic matter (abundance) differences and also cannot comment at things at the speed of light. In that sense it is Euclidean or perhaps Newtonian.
But what is interesting is that this toy example gives us a concrete way to understand right and left. You can choose anything to call left and anything to call right. But the side at which your heart is of your body will be switched at t<0. Additionally, and this is the only part that I find important or useful, we have actually partitioned things now according to whether they internally define left and right in the usual way or in the opposite way. And finally, we can even now say that subatomic particles that decide to decay as matter or antimatter now self-identify themselves for us and their choice of chirality determines their position at either x > 0 or -x < 0.
EDIT: Disclaimer: I am a mathematician, not a physicist.
We can imagine all sorts of arbitrary transformations of our universe into various geometrical forms, but they're just imaginary. What turns speculation like this into physics is a mechanism.
Yes sure, that's true. But what my toy example does provide a way to understand chirality and what it means to switch chirality. As far as I can tell, mathematics is agnostic with regards to chirality. But we can partition into two sets the universe of objects according to their internal resolution of their choice of a left/right axis. We will know then that all the ones in t>0 and t<0 are grouped together, respectively, but we don't know which is the set t>0 and which is t<0 as they both look exactly the same.
You would have to account for the fact that the earth is moving around the sun, the sun around the galactic core, and so on.
Their time backwards is our time forwards, but penguins at the south pole, polar bears at the north pole, and all the birds in every tropical jungle near the equator will watch the moon and the stars spin across the sky, as evolutionary eons pass.
If we pass through some kind of temporal lens, and at the zero crossing, we come to understand the other side is an equal but opposite negation of ourselves, a look into the temporal mirror still doesn’t unlock the future. We’ll only catch an alternative perspective of now, and we also can’t do much to treat the mirror like furniture. There’s only one arrow of time, and the reflection isn’t separate and distinct just as shadows are anymore separate and distinct from the objects that cast them.
This article speaks about mirror universe that exists in the same 3+1 dimensional space-time as ours. It's just that the two are transparent to each other. Only gravity ties them together.
If this concept is interesting to you, Greg Egan has written an entire scifi novel (Dichronauts) set in a 2+2 universe. Weirdness abounds, but quite rigorous.
Was going to highlight that book too. It's also helpful / fun to explore the articles and visualizations outside the book either before/during/after reading it. https://www.gregegan.net/DICHRONAUTS/DICHRONAUTS.html
In this mirror universe, do the men have goatees and compassion is seen as a weakness? If so, I have a few theories on how we can find that universe...
I liked the original form of this idea better, when it was hypothesized that universes are packed into a stack-like structure of membranes, although the mirror hypothesis has the benefit of being theoretically accessible to experimentation.
There are a couple of neat effects that fall out of the (mem)brane hypothesis. For example, it offers a model for why gravity is seemingly so weak compared to the other forces: because a large part of it leaks out into neighboring universes. In that case, we'd have a handy explanation for dark matter as well: it's gravity that leaks in from neighboring universes. This would mean that stuff clumps together across universes. It could also be an auxiliary model for black hole formation in certain cases where we have yet to find out how some black holes could grow very quickly.
If we ever become a K3 civilization we could attempt to send a message across universes with gravity, or possibly even paint a symbol into the sky using large masses. Not we know how likely the other universes are to support life (probably not very).
I don't know since merely controlling the area is not enough, you'd have to capture (and use) all the stellar energy that comes out of that region. So K4 could be something like "uses the energy of the entire visible universe", but that's a shrinking concept over the time scales in question.
It's not a well-defined scale anyway, since you could probably build a K3-equivalent civilization with only a few star systems using miniature black holes as reactors; conversely, you could easily be a galaxy-spanning civilization but only use a fraction of the total stellar output.
The concept of translating into another universe does seem like an appropriate achievement and next step after K3. Since another universe might have wildly different basic parameters, classical sci-fi portals and such are probably out of the question. You'd have to translate the information stored in the brain into something appropriate that could continue to perform roughly the same functions on the other side.
With a gravity well, to be sure. We can reflect and collimate beams, but I don’t think there’s much success capturing sizable volumes of free neutron particles in a chamber.
We know that we can collect neutrons into a degenerate gas. But it probably all tends to sink toward the center of the earth, like subatomic bouncy balls.
It’s still theoretical though. We haven’t bottled it for sale yet. It would probably have lots of interesting applications, not the least of which would include weaponization.
It’s probably a magnetic bottle. Despite not having any net electric charge, neutrons have a magnetic moment. Not being a physicist I have no idea how to calculate their behaviour in a magnetic field, but I am aware they respond to one.
With very cold temperatures and magnets. The article had a link to a much better article in Science Mag [1] with more information about how neutrons are trapped.
This reminds me of 'The Gods Themselves', by Asimov. Doesn't talk about a mirror universe per se, but a parallel one. It's one of my favourite Asimov stories outside the Foundation/Robots series.
Personally I think it is Asimov's best work, with I Robot not far behind and Foundation in a distant third. Honestly not sure why people are so enamored of Foundation.
I disliked The Gods Themselves when I read it the first time because of all the freaky alien sex that was described in so much detail. Of course I was a child at the time.
I liked Foundation because of the series aspect - it was a cool premise and it was good to have so many books cover it thoroughly. I did find the last bits that were just to tie it together with the Elijah Bailey stories to be boring.
>Doesn't talk about a mirror universe per se, but a parallel one. It's one of my favourite Asimov stories
This reminds me of the two-part episode in Season 4 of "Enterprise", "In a Mirror, Darkly", which was probably the best episode of the series, and definitely had the very best opening sequence and music of the show.
They might have already found us, and realized that we were the "evil twin" universe where humans are malevolent, and have decided to avoid all contact with us.
Mirror universes are a popular plot line in Sci-Fi so there are plenty of source materials to reference. However the HN community generally disapproves of pop culture references and jokes unless they're presented in an informative context.
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This is a semantic problem, not a physical. Generally, there is no single definition of the word 'universe' that all physicists ascribe to. When you have causally disjoint set of spacetimes that may or may not be governed by the same set of physical laws, some people choose call these multiple universes.
It is more about studying the universe within a framework than about going through a magic door to other universes. For example, if you take a mathematical group one thing you can do is view every group as a group of permutations. That changes the "framework" but it is equivalent to working with an alternate encoding of the group.
Similar to what happened with the word atom, it literally means indivisible, but instead of renaming atoms, we just kept adding other names when we found out the atom was actually very much divisible.
The assignment and communication of meaning is a fascinating topic/problem that affects pretty much everything we do, yet it's usually invisible or transparent to us most of the time.
I was under the impression baryonic matter has been strongly excluded as a candidate for dark matter, because dark matter does not seem to clump together; it seems to interact with itself only through gravity as well. So it can't be any kind of baryonic matter, in a mirror universe or a nearby brane or anything like that, which is also why the idea of "dark matter life" does not seem likely; you can't build life out of a material that interacts with itself only gravitationally.
Although, do free neutrons clump?
Then again, if the neutrons oscillate to "mirror" and then have a high probability of coming back, presumably an independent probability over time, that can't be dark matter either since it tunnels back on timeframes even humans consider short.
Anyhow, on the article's own terms, the connection to dark matter seems tenuous.
So the mirror universe is where the dark matter we can't find is, and for some reason it just happens to form halos around where our galaxies are, just to make their rotations weird. This is a strangely specific mirror universe.
If our scientists are trying to inject neutrons into a mirror universe, are mirror-world scientists trying to inject neutrons into ours? Could we detect that if they did?
Don't know enough physics to talk about the specifics of this particular experiment/research. But, it seems to me, that we live in the midst of the intersection of the "real" world and the mirror one. Similar to Newton's third law (action/reaction), for anything to exist (or make sense to us), the complement of that thing needs to exist too. For example, if there was only one color, there would be no colors, we need for two colors to exist so we can tell them apart. Things only make sense to us in contrast to what they are not.
Following the above concept, you could "split up" (conceptually) the world/universe into explicit complements and you'd have the universe and its mirror. And this is in fact a very old concept, very well illustrated by the yin and yang.
According to modern physics, the total energy of our universe is in fact zero, with matter and radiation contributing to "positive" energy, and gravity and other quantum effects contributing to "negative" energy. This is actually the reason we're able to say that our universe could have arisen from nothing, since only a universe with zero total energy can do that.
Therefore, by Occam's razor, we don't need another "mirror" universe to balance out this one.
I had never considered it like that, but it feels true. Do you have some reference material for the statement that gravity and quantum effects are “negative energy”?
It's not difficult to derive why the gravitational potential energy must be negative.[0]
For the cosmological implications of this fact, there's Lawrence Krauss's book "A Universe from Nothing", also "The Inflationary Universe" by Alan Guth, and Stephen Hawking touches on it in "A Brief History of Time."
64 comments
[ 3.6 ms ] story [ 76.2 ms ] threadAs I understand it, this mirror world would be colder than our own and this would affect nucleosynthesis in the early universe. There would be significantly more helium and less heavier particles. Because the mirror universe is connected to our universe trough gravity, we would definitely notice is dark matter stars and planets would go buy. Our universe would have more dense points of matter and the mirror universe would have more light gas clouds circling roughly at the same area as galaxies in our world.
Here is a paper from 2000 "The Early Mirror Universe: Inflation, Baryogenesis, Nucleosynthesis and Dark Matter" https://arxiv.org/abs/hep-ph/0008105
Just as in the Casimir experiment it was demonstrated that opposed conductive plates are attracted with a force that results from the suppression of vacuum energy states between them, so must the decay of the neutron be modulated by the vacuum field.
If you contrive the storage system to suppress the vacuum energy to a greater extent, the field will interact less with free neutrons and they will live a little longer. Likewise, the more possible energy states, the shorter they live.
This effect is apparent because the free neutron is quite unstable and short-lived. It is readily affected by the particle-antiparticle pairs that are always popping into and out of existence in the vacuum.
Protons, which are very stable and last a long time, show the same effect, but you would be long dead by the time you observed it. So not a practical experiment.
Why does a radioactive element decay at a particular time? Why is it random? Why is Schroedinger's cat a superposition of alive/dead with no way of predicting which one until you observe it and collapse the wave equation?
The answer to all of these is the same. The background state of the universe is chaotic. It visibly affects things that are unstable, while not having much effect on things that are stable.
The faster something is moving, the more mass it has. The more mass, the less it is affected by the vacuum field. This is the mechanism of time dilation. Increased mass, decreased size, increased density, surrounded by mass, all of these contrive to suppress the interaction of the vacuum field with an object by limiting the possible states it can occupy.
The outcome looks to us like order, but it's not. Everything is randomness and chaos.
Newton's laws are approximations because they apply simple math to chaos. Likewise, general relativity is a geometric theory applied to a chaotic universe. It's a good approximation of what we see, but it's only an approximation. No geometric theory can explain something that is fundamentally chaotic.
There. Is. No. Meaning.
Sleep well!
It's kind of an interesting thought experiment to try to put yourself in the mindset of a people before the discovery of something and trying to imagine how you would have perceived the world and if you yourself might have conceived of such notions. For instance the idea that all objects fall at the same rate of speed is something that's oddly enough an extremely recent discovery. The tale of the apple falling on Newton's head dates to but 350 years ago. We, of today, are separated by then by little more than about 4 lifetimes.
It feels at times that science progresses through 1% genius and 99% creativity. Newton's gravity is, relative to the times, no more simple or complex than Einstein's gravity and undoubtedly whatever we may eventually find to be the source of dark matter. The tricky part is that the universe has this habit of requiring us to cast aside what we think we know and look towards paths that seem insane. A feather falls at the same rate of speed as a bowling ball? Time itself can move differently for people in the same location based upon their relative velocities? Physical distances can literally contract or expand again for people in the same location and again based on their relative velocities? Objects themselves can bend what seems to be emptiness and, in turn, bend light itself (to say nothing of also having an impact on time)? These ideas are mostly so difficult to develop not because of mathematical or technical problems, but because they sound insane. It's really quite a blessing for the inquisitive and creative that we seem to live in a universe that prides itself in as being as defiant of intuition as it possibly can.
It would have to be taught in high scholl, and even then not everyone have a complete high school knowledge. People don't generally know Newtonian mechanics unless they are physics undergrads or graduates. You need calculus to get it.
I would argue that Newton's theory was more complex because it required new math. Einstein didn't. The math was already there, and he managed to incept his idea without it. Riemannian geometry just simplified description. It's similar to Maxwell. He had electromagnetism in over 20 equations, then some lad whose name I forgot, made work and closed it down to four, that again 99 percent or more people don't know, though they govern nearly everything at our scale. Touch, vision and chemistry is described by them. I can come with only two things that are part of everyday life, that lie outside. Gravity, in the part that makes us stick to the planet, and atomic energy, though that's fast trasformed back to EM domain. Everything else seems to be far away, except for the fact they make things stable, but we don't harness it.
To me ingenuity and creativity are essentially the same. It's the abilty to have those insane ideas, perhaps genius is to pick important ones to ponder upon. I think we agree, that scientific breakthroughs seem to be based on making up grander picture, where what you physically see is some kind of special case of generally opposite rules. One of the greatest example is the idea that movement is generally self sustained, seems crazy here in the atmosphere, where the 1st theories said, that it requires force and work to keep going. Something we all experience.
Well, that's a long tought-chain. Hope someone's find it interesting.
Quantum mechanics required the weirdness of the blackbody radiation spectrum to spring to life. The special theory of relativity is based on the observation that the Maxwell equations are not Galileo invariant and the results of their strange Lorentz invariance can be observed. The general theory of relativity is baed on the realization that despite efforts to measure a difference, inertial mass and gravitational mass always have the same value.
It took time for these things to become measurable and to make people go "hmmm..." and think about nature in new ways. The answers are creative and genial, but they required starting points. And creating those takes time.
If we take our three spacial dimensions, and add another time dimension, then we can do a reflection at t=0 and this will produce a mirror object of everything from t>0 at t<0. (Note that in three dimensions, if we perform a reflection it is the same as a rotation when we add a fourth dimension, meaning we can do this "mechanically" if that is worth anything to you.)
This universe at t<0 looks exactly the same as our universe at t>0, except that you switch chirality (or left and right if you will). Now my toy example does not have exotic matter (abundance) differences and also cannot comment at things at the speed of light. In that sense it is Euclidean or perhaps Newtonian.
But what is interesting is that this toy example gives us a concrete way to understand right and left. You can choose anything to call left and anything to call right. But the side at which your heart is of your body will be switched at t<0. Additionally, and this is the only part that I find important or useful, we have actually partitioned things now according to whether they internally define left and right in the usual way or in the opposite way. And finally, we can even now say that subatomic particles that decide to decay as matter or antimatter now self-identify themselves for us and their choice of chirality determines their position at either x > 0 or -x < 0.
EDIT: Disclaimer: I am a mathematician, not a physicist.
Their time backwards is our time forwards, but penguins at the south pole, polar bears at the north pole, and all the birds in every tropical jungle near the equator will watch the moon and the stars spin across the sky, as evolutionary eons pass.
If we pass through some kind of temporal lens, and at the zero crossing, we come to understand the other side is an equal but opposite negation of ourselves, a look into the temporal mirror still doesn’t unlock the future. We’ll only catch an alternative perspective of now, and we also can’t do much to treat the mirror like furniture. There’s only one arrow of time, and the reflection isn’t separate and distinct just as shadows are anymore separate and distinct from the objects that cast them.
This article speaks about mirror universe that exists in the same 3+1 dimensional space-time as ours. It's just that the two are transparent to each other. Only gravity ties them together.
What is an intuitive explanation of what being in a 3+0 spacetime would be like? Since there's no time, nothing can "happen"...
Imagine a 3D object squashed between two glass plates until it's a single plane. You can see everything without changing focus.
I see "We are here" and think...well, sorta, but if the graph were continuous we're at exactly (3.0,1.0) or so it seems.
There are a couple of neat effects that fall out of the (mem)brane hypothesis. For example, it offers a model for why gravity is seemingly so weak compared to the other forces: because a large part of it leaks out into neighboring universes. In that case, we'd have a handy explanation for dark matter as well: it's gravity that leaks in from neighboring universes. This would mean that stuff clumps together across universes. It could also be an auxiliary model for black hole formation in certain cases where we have yet to find out how some black holes could grow very quickly.
If we ever become a K3 civilization we could attempt to send a message across universes with gravity, or possibly even paint a symbol into the sky using large masses. Not we know how likely the other universes are to support life (probably not very).
It's not a well-defined scale anyway, since you could probably build a K3-equivalent civilization with only a few star systems using miniature black holes as reactors; conversely, you could easily be a galaxy-spanning civilization but only use a fraction of the total stellar output.
The concept of translating into another universe does seem like an appropriate achievement and next step after K3. Since another universe might have wildly different basic parameters, classical sci-fi portals and such are probably out of the question. You'd have to translate the information stored in the brain into something appropriate that could continue to perform roughly the same functions on the other side.
It seems that in the crucial part the article makes gross oversimplification. I would imagine storage impacts observed half-life.
We know that we can collect neutrons into a degenerate gas. But it probably all tends to sink toward the center of the earth, like subatomic bouncy balls.
https://en.wikipedia.org/wiki/Neutronium
It’s still theoretical though. We haven’t bottled it for sale yet. It would probably have lots of interesting applications, not the least of which would include weaponization.
[1] https://science.sciencemag.org/content/360/6389/627
I liked Foundation because of the series aspect - it was a cool premise and it was good to have so many books cover it thoroughly. I did find the last bits that were just to tie it together with the Elijah Bailey stories to be boring.
This reminds me of the two-part episode in Season 4 of "Enterprise", "In a Mirror, Darkly", which was probably the best episode of the series, and definitely had the very best opening sequence and music of the show.
The definition of THE universe is: "all existing matter and space considered as a whole; the cosmos".
The assignment and communication of meaning is a fascinating topic/problem that affects pretty much everything we do, yet it's usually invisible or transparent to us most of the time.
Although, do free neutrons clump?
Then again, if the neutrons oscillate to "mirror" and then have a high probability of coming back, presumably an independent probability over time, that can't be dark matter either since it tunnels back on timeframes even humans consider short.
Anyhow, on the article's own terms, the connection to dark matter seems tenuous.
The quality level here smacks of 1999 vintage Onion:
https://www.theonion.com/worlds-top-scientists-ponder-what-i...
Or is the 'portal' mechanism triggered so rarely that we would probably never observe it happening naturally?
Following the above concept, you could "split up" (conceptually) the world/universe into explicit complements and you'd have the universe and its mirror. And this is in fact a very old concept, very well illustrated by the yin and yang.
Therefore, by Occam's razor, we don't need another "mirror" universe to balance out this one.
For the cosmological implications of this fact, there's Lawrence Krauss's book "A Universe from Nothing", also "The Inflationary Universe" by Alan Guth, and Stephen Hawking touches on it in "A Brief History of Time."
[0] https://en.wikipedia.org/wiki/Gravitational_energy