Dark Matter From 12 Billion Years Ago Detected For the First Time (space.com) 18
Scientists have discovered dark matter around galaxies that existed about 12 billion years ago, the earliest detection yet of this mysterious substance that dominates the universe. Space.com reports: The findings, achieved by a collaboration led by researchers from Japan's Nagoya University, suggest that dark matter in the early universe is less 'clumpy' than predicted by many current cosmological models. If further work confirms this theory, it could change scientists' understanding of how galaxies evolve and suggest that the fundamental rules governing the cosmos could have been different when the 13.7 billion-year-old universe was just 1.7 billion years old. The key to mapping dark matter in the very early universe the cosmic microwave background (CMB), a sort of fossil radiation left over from the Big Bang that is distributed throughout the entire cosmos. [...]
The team combined lensing distortions of a large sample of ancient galaxies with those of the CMB to detect dark matter dating back to when the universe was just 1.7 billion years old. And this ancient dark matter paints a very different cosmic picture. "For the first time, we were measuring dark matter from almost the earliest moments of the universe," [University of Tokyo assistant professor Yuichi Harikane said in the statement]. "12 billion years ago, things were very different. You see more galaxies that are in the process of formation than at the present; the first galaxy clusters are starting to form as well." These clusters can be comprised of between 100 and 1,000 galaxies bound to large amounts of dark matter by gravity.
"Our finding is still uncertain," Harikane said. "But if it is true, it would suggest that the entire model is flawed as you go further back in time. This is exciting because if the result holds after the uncertainties are reduced, it could suggest an improvement of the model that may provide insight into the nature of dark matter itself." The team will continue to collect data to assess whether the Lambda-CDM model conforms to observations of dark matter in the early universe or if the assumptions behind the model need to be revised.
The team combined lensing distortions of a large sample of ancient galaxies with those of the CMB to detect dark matter dating back to when the universe was just 1.7 billion years old. And this ancient dark matter paints a very different cosmic picture. "For the first time, we were measuring dark matter from almost the earliest moments of the universe," [University of Tokyo assistant professor Yuichi Harikane said in the statement]. "12 billion years ago, things were very different. You see more galaxies that are in the process of formation than at the present; the first galaxy clusters are starting to form as well." These clusters can be comprised of between 100 and 1,000 galaxies bound to large amounts of dark matter by gravity.
"Our finding is still uncertain," Harikane said. "But if it is true, it would suggest that the entire model is flawed as you go further back in time. This is exciting because if the result holds after the uncertainties are reduced, it could suggest an improvement of the model that may provide insight into the nature of dark matter itself." The team will continue to collect data to assess whether the Lambda-CDM model conforms to observations of dark matter in the early universe or if the assumptions behind the model need to be revised.
Teenage years (Score:3)
The team combined lensing distortions of a large sample of ancient galaxies with those of the CMB to detect dark matter dating back to when the universe was just 1.7 billion years old.
They can see back to the universe's teenage years. Even though this is good, they still a little farther back to go to unlock a few questions.
Grr. (Score:5, Insightful)
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It's right in TFS. No need to get sucked in. It's just bullshit, just like every other claim to have found it.
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Why do I get sucked into these clickbait headlines? Dark matter was not detected- the apparent effect of dark matter was detected.
If you want to be pedantic, the same can be said of *anything* that is "detected".
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I came here to call bullshit in the comments, GJ.
Milgromian dynamics (Score:2)
Maybe it's not "dark matter," maybe it's just that the models being used are incorrect. "Extraordinary claims require extraordinary evidence." -- Carl Sagan
Early universe is where controversy may be decided (Score:4, Interesting)
There is a small community of dark-matter deniers, of which Pavel Kroupa may be the most entertaining speaker among proponents of that viewpoint.
What I gather from his YouTube videos is that Milgrom's MOND (Modified Newtonian Dynamics) explains individual galaxies and interactions between small numbers of galaxies well, with Kroupa claiming that critics haven't performed detailed simulations of the dynamics of galaxies as he has. The Bullet Cluster is heralded by dark-matter believers as where MOND breaks down, but Kroupa asserts this isn't so.
In a "debate" with a Believer, Kroupa as much as admits that the Early Universe is a potential area of weakness in claiming MOND, especially when you go back to the very early universe described by in homogeneities of the Microwave Cosmic Background. One track he takes is that, yes, some form of Dark Matter is required in the Early Universe, but because of the uniformity of the inferred Dark Matter, it could be hot dark matter in the form of neutrinos, recently in physics history discovered to have mass, rather than some exotic, undiscovered even after massive efforts, heavy cold-dark matter particle -- weakly interacting massive particles or WIMPs.
Kroupa also whinges that a proper test of MOND in the Early Universe would require a relativistic dynamic simulation, for which a computer programmer with enough physics knowledge is hard to find and for whom no one will give him money to hire because as a Dark Matter Denier, Kroupa is in the out-group of who gets their grants funded.
Physicist Sabine Hossenfelder attempts to split the difference between Deniers and Believers, stating that Quantum Mechanics establishes a duality between a field and a particle, and that the source of the discrepancy in the dynamics of galaxies and other cosmic-scale structures could be both field (MOND) or a particle (Dark Matter). For those of you old enough to have watched Saturday Night Live in the late 70's, it is like Sparkle, both a floor wax and a dessert topping.
IANAAP, but based on that speculation, a better way of framing the controversy is not between Dark Matter and MOND, but rather, between whether the undiscovered field or particle is collocated with visible matter, giving the MOND correction to F=ma, or whether it can clump independently from the clumping of visible matter, which is the gravitational effect of Cold Dark Matter.
"Extraordinary claims" (Score:1)
Sometimes that saying is misused or misleading. Much of cosmology is contest among competing theories. None is necessarily more "extraordinary" than others. They are all extraordinary, but it's all we got. We use Occam's razor to select the "current best candidate", and dark matter is currently the top candidate for various observation oddities.
And further, the saying is sometimes used to shut down research and curiosity. "UFO's are alien spaceships" is indeed an "extraordinary" claim. But not, "UFO's are
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Wow, please give us citations to the peer-reviewed journals where you refuted all those papers on dark matter. I'm sure we'd all love to read them, because there's no way you'd just say something that colossally ignorant, right?
First time... (Score:3)
First time...and about time? Better late than never.
Although I often wonder if "dark matter" is akin to the old obsolete theory of "aether" that filled the vacuum of space with some undetectable substance for light propagation through space. Dark matter is not about light transmission, but seems the same kind of nebulous concept as New Scientist [newscientist.com] explains.
JoshK.