I wonder if it has a goatee.
February 18, 2024 10:03 AM Subscribe
The invisible substance called dark matter remains one of the biggest mysteries in cosmology. Perhaps, a new study suggests, this strange substance arises from a 'dark mirror universe' that's been linked to ours since the dawn of time.
If I'm reading this article right, the hypothesis posits the existence of an ideal universe in which protons have the correct mass and therefore cannot bind together and form stable atoms. If the protons in the broken, mirror universe in which we live had only been slightly heavier, we, too, could exist only as a peaceful sea of free-floating neutrons.
posted by Faint of Butt at 10:34 AM on February 18 [3 favorites]
posted by Faint of Butt at 10:34 AM on February 18 [3 favorites]
No, the "mirror universe" is not a new hypothesis. But coming up with testable predictions is tough.
When I was active in nuclear physics there was an ongoing proposal to put a neutron source at the entrance to a huge evacuated region with zero magnetic field, so the neutrons would be free to "rotate" into undetectable "mirror neutrons." But making zero magnetic field is hard. Experiments whose result is "the beam gets slightly less intense" are hard. There is a measurement that, if isolated neutrons disappear into the mirror-matter sector, their lifetime is longer that some minimum. But that limit is not interesting compared to the neutron beta decay lifetime, which has its own measurement challenges.
posted by fantabulous timewaster at 10:39 AM on February 18 [7 favorites]
When I was active in nuclear physics there was an ongoing proposal to put a neutron source at the entrance to a huge evacuated region with zero magnetic field, so the neutrons would be free to "rotate" into undetectable "mirror neutrons." But making zero magnetic field is hard. Experiments whose result is "the beam gets slightly less intense" are hard. There is a measurement that, if isolated neutrons disappear into the mirror-matter sector, their lifetime is longer that some minimum. But that limit is not interesting compared to the neutron beta decay lifetime, which has its own measurement challenges.
posted by fantabulous timewaster at 10:39 AM on February 18 [7 favorites]
Is this a new 'study' or a new hypothesis?
As I read it (and I have a few times now trying to understand what data backs this up), it is entirely a new hypothesis, and that is all.
That said, as it relates to Dark Matter, I'm not sure how much more would be possible.
The previous work on the authors seems abundant and on topic, so I would assume this is a hypothesis based in a great degree of understanding.
posted by dogbusonline at 10:40 AM on February 18 [3 favorites]
As I read it (and I have a few times now trying to understand what data backs this up), it is entirely a new hypothesis, and that is all.
That said, as it relates to Dark Matter, I'm not sure how much more would be possible.
The previous work on the authors seems abundant and on topic, so I would assume this is a hypothesis based in a great degree of understanding.
posted by dogbusonline at 10:40 AM on February 18 [3 favorites]
Brilliant job on the post title. I busted out in laughter. Evil, maniacal laughter.
posted by armoir from antproof case at 10:47 AM on February 18 [3 favorites]
posted by armoir from antproof case at 10:47 AM on February 18 [3 favorites]
I would also like to complain about this chain of pop-science journalism:
"There is more dark matter than regular matter. Five percent of the energy density of the universe is ordinary matter, and 26.8% is dark matter."
"That's too complicated."
"Well, it's about a factor of five. For every kilogram of ordinary matter, there are 5 kilograms of dark matter."
"Yes, but I'm afraid of the metric system."
"Well, a kilogram is about two pounds."
The article: "For every 2 pounds (1 kilogram) of ordinary matter, there are 10 pounds (5 kilograms) of dark matter."
It could have been worse. They could have blindly copied an online converter and written the ratio as 2.205 pounds to 11.025 pounds (which is precise enough that it's actually inaccurate).
posted by fantabulous timewaster at 10:51 AM on February 18 [6 favorites]
"There is more dark matter than regular matter. Five percent of the energy density of the universe is ordinary matter, and 26.8% is dark matter."
"That's too complicated."
"Well, it's about a factor of five. For every kilogram of ordinary matter, there are 5 kilograms of dark matter."
"Yes, but I'm afraid of the metric system."
"Well, a kilogram is about two pounds."
The article: "For every 2 pounds (1 kilogram) of ordinary matter, there are 10 pounds (5 kilograms) of dark matter."
It could have been worse. They could have blindly copied an online converter and written the ratio as 2.205 pounds to 11.025 pounds (which is precise enough that it's actually inaccurate).
posted by fantabulous timewaster at 10:51 AM on February 18 [6 favorites]
Another interesting read on dark matter came up recently on Quanta: the Dark Dimension; the idea is that if one of the extra tiny universes in string theory were much bigger than the others ... complicated gravity things would happen ... and ... tada!
(in case you can't tell, I read Quanta for the pictures, not the articles.)
Despite this stemming from string theory it does actually make a testable hypothesis - albeit one that would require measuring the gravitational attraction between two objects a micron apart, which is 50 times more accurate than currently possible.
posted by protorp at 10:56 AM on February 18 [5 favorites]
(in case you can't tell, I read Quanta for the pictures, not the articles.)
Despite this stemming from string theory it does actually make a testable hypothesis - albeit one that would require measuring the gravitational attraction between two objects a micron apart, which is 50 times more accurate than currently possible.
posted by protorp at 10:56 AM on February 18 [5 favorites]
> "It could have been worse."
"Vergon 6 was once filled with the super-dense substance known as Dark Matter, each pound of which weighs over 10,000 pounds."
posted by kyrademon at 11:27 AM on February 18 [6 favorites]
"Vergon 6 was once filled with the super-dense substance known as Dark Matter, each pound of which weighs over 10,000 pounds."
posted by kyrademon at 11:27 AM on February 18 [6 favorites]
There are a lot of mathematically appealing, basically untestable hypotheses like this, especially coming out of string theory. String theory is math focused, and has a lot of freedom to change parameters around to get interesting results
posted by The Manwich Horror at 11:49 AM on February 18
posted by The Manwich Horror at 11:49 AM on February 18
If nothing else, I have now been introduced to the term reheaton, which I will be using inaccurately during cooking from now on.
posted by mittens at 1:09 PM on February 18 [8 favorites]
posted by mittens at 1:09 PM on February 18 [8 favorites]
>"Based on observational tests of large scale structure and constraints on halo structure, dark matter is generally taken to be cold and essentially collisionless. On the other hand, given the large number of particles and forces in the visible world, a more complex dark sector could be a reasonable or even likely possibility. This hypothesis leads to testable consequences, perhaps portending the discovery of a rich hidden world neighboring our own. We consider a scenario that readily satisfies current bounds that we call Partially Interacting Dark Matter (PIDM). This scenario contains self-interacting dark matter, but it is not the dominant component. Even if PIDM contains only a fraction of the net dark matter density, comparable to the baryonic fraction, the subdominant component’s interactions can lead to interesting and potentially observable consequences."
"Physicists: A mirror universe might explain dark matter
Denyse O'Leary January 10, 2019"
posted by clavdivs at 1:50 PM on February 18 [1 favorite]
"Physicists: A mirror universe might explain dark matter
Denyse O'Leary January 10, 2019"
posted by clavdivs at 1:50 PM on February 18 [1 favorite]
These are testable claims. The abstract explains:
there can naturally be order-one couplings mediated by TeV scale particles which can allow experimental probes of the dark sector at high energy colliders.
This is why CERN is looking to build the FCC a 100 TeV particle collider to look for these kinds of particles. This compares to the LHC at 14 TeV.
However, Sabine Hossenfelder would probably point out this is a multi-billion dollar stab in the dark as there's very little evidence for dark matter particles.
posted by betaray at 4:35 PM on February 18 [2 favorites]
there can naturally be order-one couplings mediated by TeV scale particles which can allow experimental probes of the dark sector at high energy colliders.
This is why CERN is looking to build the FCC a 100 TeV particle collider to look for these kinds of particles. This compares to the LHC at 14 TeV.
However, Sabine Hossenfelder would probably point out this is a multi-billion dollar stab in the dark as there's very little evidence for dark matter particles.
posted by betaray at 4:35 PM on February 18 [2 favorites]
"dark matter" is just rebranded phlogiston. something is wrong with the way they're doing the math.
posted by graywyvern at 4:37 PM on February 18 [2 favorites]
posted by graywyvern at 4:37 PM on February 18 [2 favorites]
The dark matter and energy is just the underlying computer memory resources and processing power of our 2D universe stored in someone else's simulation.
Do you really think THIS time line with the amount of plot armour for great historical figures is in anyway reasonable? Ha!
posted by Comstar at 4:56 PM on February 18 [1 favorite]
Do you really think THIS time line with the amount of plot armour for great historical figures is in anyway reasonable? Ha!
posted by Comstar at 4:56 PM on February 18 [1 favorite]
This time for sure!
I lost my faith in dark matter after the first 50 years. If the "missing mass" is ever found it will likely be running a perpetual motion machine.
Time to give up and recognize that our traditional model of gravity doesn’t cover all the angles at very large scales.
posted by Tell Me No Lies at 5:11 PM on February 18 [1 favorite]
I lost my faith in dark matter after the first 50 years. If the "missing mass" is ever found it will likely be running a perpetual motion machine.
Time to give up and recognize that our traditional model of gravity doesn’t cover all the angles at very large scales.
posted by Tell Me No Lies at 5:11 PM on February 18 [1 favorite]
"dark matter" is just rebranded phlogiston.
I remember having this debate with a chemistry professor at University. this is where judo comes in handy.
posted by clavdivs at 9:07 PM on February 18
I remember having this debate with a chemistry professor at University. this is where judo comes in handy.
posted by clavdivs at 9:07 PM on February 18
Phlogiston supporter or phlogiston denier?
posted by flabdablet at 1:48 AM on February 19 [1 favorite]
posted by flabdablet at 1:48 AM on February 19 [1 favorite]
> "Time to give up and recognize that our traditional model of gravity doesn’t cover all the angles at very large scales."
This really doesn't account for the observational evidence. As one example, there's the Bullet Cluster, where the center of mass and the baryonic center of mass are in two different places. That's easy to explain if there's something else there. It's a lot harder to explain if it has to be, "large-scale gravity is different in some way which affects the Bullet Cluster in a manner that it doesn't for most other places we've observed that puts its center of mass in a different place than its center of mass."
posted by kyrademon at 5:08 AM on February 19 [9 favorites]
This really doesn't account for the observational evidence. As one example, there's the Bullet Cluster, where the center of mass and the baryonic center of mass are in two different places. That's easy to explain if there's something else there. It's a lot harder to explain if it has to be, "large-scale gravity is different in some way which affects the Bullet Cluster in a manner that it doesn't for most other places we've observed that puts its center of mass in a different place than its center of mass."
posted by kyrademon at 5:08 AM on February 19 [9 favorites]
The Law of Cosines is a lot tougher to explain than the Pythagorean Theorem, and yet it gives us the tool we need to move beyond the simple case.
posted by Tell Me No Lies at 6:26 AM on February 19 [1 favorite]
posted by Tell Me No Lies at 6:26 AM on February 19 [1 favorite]
I mean, sure. And there's been no knock-down proof that Modified Newtonian Dynamics isn't the answer. But literally all the evidence that's been coming in recently -- from the acoustic peaks in the Cosmic Microwave Background to the mass centers of post-collision galactic clusters to the galaxies that behave as if they are "dark matter free" (or unaffected by modified gravity, if you prefer) -- are better explained by dark matter than by modified gravity.
That doesn't mean it's Definitely Wrong, but with all the evidence coming down on the other side, the hill modified gravity theory has to climb is getting steeper and steeper.
posted by kyrademon at 7:08 AM on February 19 [3 favorites]
That doesn't mean it's Definitely Wrong, but with all the evidence coming down on the other side, the hill modified gravity theory has to climb is getting steeper and steeper.
posted by kyrademon at 7:08 AM on February 19 [3 favorites]
There is no dark side of the universe, really. Matter of fact, it's all dark.
posted by kirkaracha at 11:02 AM on February 19 [2 favorites]
posted by kirkaracha at 11:02 AM on February 19 [2 favorites]
That doesn't mean it's Definitely Wrong, but with all the evidence coming down on the other side, the hill modified gravity theory has to climb is getting steeper and steeper.
There’s no question that dark matter is a better explanation, but we’ve been theorizing and gathering evidence and in general spending our intellectual resources on it for 50 years now with no substantial process on actually finding it.
I’m not suggesting abandoning the search, but I do think it’s time to take a big step back and think about whether our understanding of gravity is in fact the understanding of a special case.
Although honestly I’m not stuck to that theory either. I am stuck to the idea that after you spend 50 years looking for something and have failed you need to widen your investigation substantially.
posted by Tell Me No Lies at 11:21 AM on February 19 [1 favorite]
There’s no question that dark matter is a better explanation, but we’ve been theorizing and gathering evidence and in general spending our intellectual resources on it for 50 years now with no substantial process on actually finding it.
I’m not suggesting abandoning the search, but I do think it’s time to take a big step back and think about whether our understanding of gravity is in fact the understanding of a special case.
Although honestly I’m not stuck to that theory either. I am stuck to the idea that after you spend 50 years looking for something and have failed you need to widen your investigation substantially.
posted by Tell Me No Lies at 11:21 AM on February 19 [1 favorite]
Phlogiston supporter or phlogiston denier?
pre or post Lavoisier.
posted by clavdivs at 2:00 PM on February 19
pre or post Lavoisier.
posted by clavdivs at 2:00 PM on February 19
It's modified phlogiston all the way down.
posted by Pouteria at 5:24 PM on February 19 [1 favorite]
posted by Pouteria at 5:24 PM on February 19 [1 favorite]
Phlogiston is more like dark energy. Dark matter would be the Luminiferous Aether. And the strings in string theory are likely composed of vril.
posted by FatherDagon at 10:32 PM on February 19 [1 favorite]
posted by FatherDagon at 10:32 PM on February 19 [1 favorite]
If there are strings (plural) composed of vril, what are the distinctions between them composed of?
posted by flabdablet at 11:08 PM on February 19 [1 favorite]
posted by flabdablet at 11:08 PM on February 19 [1 favorite]
If there are strings (plural) composed of vril, what are the distinctions between them composed of?
Vron't.
posted by The Manwich Horror at 5:56 AM on February 20 [4 favorites]
Vron't.
posted by The Manwich Horror at 5:56 AM on February 20 [4 favorites]
In the history of solar system science we've had orbital anomalies explained by unseen planets where:
* The planet exists and causes the anomalies
* The planet coincidentally exists but wasn't causing the anomalies: our planetary mass estimates were simply wrong.
* The planet doesn't exist: our theory of gravitation was subtly wrong.
So is dark matter more like Neptune, Pluto, or Vulcan? I think dark matter will turn out like Neptune, because it's not just in galactic rotation curves where we see its gravitational effect.
posted by mscibing at 9:17 AM on February 20
* The planet exists and causes the anomalies
* The planet coincidentally exists but wasn't causing the anomalies: our planetary mass estimates were simply wrong.
* The planet doesn't exist: our theory of gravitation was subtly wrong.
So is dark matter more like Neptune, Pluto, or Vulcan? I think dark matter will turn out like Neptune, because it's not just in galactic rotation curves where we see its gravitational effect.
posted by mscibing at 9:17 AM on February 20
The first manned mission to a naked singularity and back had collected enough data to keep the cosmologists buzzing for decades.
The astronauts back at the Space Center, eating in the cafeteria.
Astronaut 1: That was so crazy. It's good to be home.
Astronaut 2: ...I don't think we're home. *points to Netflix on the television on the wall, as a 'Regular Mirror' episode starts.*
posted by otherchaz at 5:22 PM on February 20 [1 favorite]
The astronauts back at the Space Center, eating in the cafeteria.
Astronaut 1: That was so crazy. It's good to be home.
Astronaut 2: ...I don't think we're home. *points to Netflix on the television on the wall, as a 'Regular Mirror' episode starts.*
posted by otherchaz at 5:22 PM on February 20 [1 favorite]
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