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Space Science

Scientists Capture First Image of Dark Matter Web (inhabitat.com) 156

Kristine Lofgren writes: Scientists have long suspected that the universe is woven together by a vast cosmic connector but, until now, they couldn't prove it. Now, for the first time ever, scientists have captured an image of a dark matter bridge, confirming the theory that galaxies are held together by a cosmic web. Using a technique called weak gravitational lensing, researchers were able to identify distortions of distant galaxies as they are influenced by a large, unseen mass -- in this case, a web of dark matter. In order to create a composite image that shows the dark matter web, scientists had to look at more than 23,000 galaxy pairs located 4.5 billion light-years away. "Results show the dark matter filament bridge is strongest between systems less than 40 million light years apart," reports Phys.Org. The findings have been published in the journal Monthly Notices of the Royal Astronomical Society.
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Scientists Capture First Image of Dark Matter Web

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  • Looks like an onion, right?

  • by techno-vampire ( 666512 ) on Thursday April 13, 2017 @01:19AM (#54226845) Homepage
    From TFA, "...researchers were able to identify distortions of distant galaxies as they are influenced by a large, unseen mass, such as dark matter." That means that what they have are images that appear to imply the existence of Dark Matter, and are hard to explain any other way, not that the images actually show us Dark Matter. That doesn't mean that it doesn't demonstrate that Dark Matter exists, it's just that the images aren't as cut and dried as the article's headline implied. It also means that there's still wiggle room for those who are certain that it doesn't exist. Still, it's a great step in the right direction.
    • by Anonymous Coward on Thursday April 13, 2017 @01:39AM (#54226883)

      Or gravity doesn't act the same over longer distances, thus there appears to be "unexplained" attraction. So yeah, either gravity is different to what we think, or dark matter exists. This "evidence" seems to suggest either option.

      • by Evtim ( 1022085 )

        Wasn't there, rather recently, a claim by some scientists that that the calculations for the movement of galaxies are not correct thus we get results that can be explained only if you introduce the concept of dark matter/energy. I have no idea how serious this is...just some vague memory that it was in the news.

        • by Zumbs ( 1241138 ) on Thursday April 13, 2017 @05:29AM (#54227221) Homepage
          Yes, there was. According to TFS [slashdot.org], they used more precise computational models which caused the need for dark matter to go away. Note that while the story was published on slashdot on April 1st, the article [newatlas.com] is from March 30th and the paper [arxiv.org] is from February 12th.
          • by Pseudonym ( 62607 ) on Thursday April 13, 2017 @06:25AM (#54227353)

            Err... no. That article was about dark energy, which isn't the same thing as dark matter.

            • Err... no. That article was about dark energy, which isn't the same thing as dark matter.

              In the Einstein universe, are they (matter & energy) not simply different states of the same thing? Being that mass and energy rarely appear separately, would not the presence of 'dark energy' strongly infer the existence of 'dark matter'?

              I would take the discovery of 'dark energy' as being at least as strongly indicative, if not more, of the existence of 'dark matter' than data from weak gravitational lensing. Of course, it also depends on how solid the evidence is, and how trustworthy the methods used

              • Conflating terms (Score:5, Informative)

                by sjbe ( 173966 ) on Thursday April 13, 2017 @07:47AM (#54227565)

                In the Einstein universe, are they (matter & energy) not simply different states of the same thing?

                Yes if one isn't being super pedantic. Your "states" analogy is reasonable. To say matter and energy are the same thing isn't exactly accurate but it's good enough for all but the most picky of purposes. But applying that relationship to so called dark matter and dark energy is a little bit fraught because we don't actually know what dark matter and dark energy are. As a result you are understandably conflating some things.

                The terms "dark matter [wikipedia.org]" and "dark energy [wikipedia.org]" are sort of placeholder terms to explain some phenomena that we don't entirely understand yet and they are more marketing terms than precise terms of art. We don't actually know for certain that what we call "dark matter" is actually matter or that "dark energy" is actually energy. We just have some observations we haven't been able to adequately explain so we needed some short hand terms to explain what we are seeing in terms of the models we have. One of three things is happening. Either we are seeing something new, we are making measurement errors, or our models are wrong. Possibly some combination of all three.

                Dark matter arises out of the fact that we see some observations that don't make sense based on the amount of baryonic ("normal") matter we can quantify. Our models of how gravity works tell us that for our observations to match our models there must be a lot more matter than we can see presuming our models are correct. So called dark energy arises out of our observations and measurements of the rate of expansion of the universe but it's even less well understood than dark matter.

                Being that mass and energy rarely appear separately, would not the presence of 'dark energy' strongly infer the existence of 'dark matter'?

                Mass is not the same thing as matter. You can have matter without mass such as with a photon. Mass is a property in some forms of matter, all of which move slower than c (the speed of light).

              • Dark Energy and Dark Matter are just _names_

                They are not connected in any way. It is not that one of them can be transformed into the other ... at least not as we know right now.

              • by suutar ( 1860506 )

                The thing is, "dark matter" and "dark energy" are explaining different things, so they are not equivalent in the same way that everyday local matter and energy are.

                The definition of "dark matter" is, in point of fact, "whatever it is that keeps galaxies from falling apart even though the outside spins faster than we think it should be able to". The definition of "dark energy" is "whatever it is that is causing distant galaxies to recede from us faster than we think they should".

                • Dark matter used to be just matter we couldn't see that explained galactic rotation. It then became also the explanation for gravitational lensing where we can't detect matter, and an explanation for the makeup of the Universe. It appears to be a form of matter that doesn't interact electromagnetically. There have been attempts to detect dark matter particles with weak interactions, with AFAIK no success yet. The idea isn't far-fetched, as neutrinos are dark matter by the definition I gave, although ne

              • would not the presence of 'dark energy' strongly infer the existence of 'dark matter'?

                No, it wouldn't infer any such thing. It might, however, IMPLY the existence of "dark matter".

                Note, by the by, that your statement above allows me to infer that you don't know the difference between "imply" and "infer".

                Alternately, in your statement above, you are implying that you don't know the difference between "imply" and "infer"....

      • Or gravity doesn't act the same over longer distances, thus there appears to be "unexplained" attraction. So yeah, either gravity is different to what we think, or dark matter exists. This "evidence" seems to suggest either option.

        Ya, but if gravity is different, to fit the current observations, it would have to be so different that nobody has been able to come up with even theoretical set of rules that it would describe how it works, and it would probably have to be non-isotropic and turn out to have some sort of polarity like magnetic force.

      • Or gravity doesn't act the same over longer distances, thus there appears to be "unexplained" attraction. So yeah, either gravity is different to what we think, or dark matter exists. This "evidence" seems to suggest either option.

        Or that there is something else that is bending the light that travels toward us. Something like a lens that can bend light due to the different index of refraction. If there was a bunch of dust and gas, and that got more dense as you moved in toward the center of the blob of dust and gas, would bend light in a similar way to what dark matter appears to do.

    • Re: (Score:3, Insightful)

      by Maritz ( 1829006 )

      It also means that there's still wiggle room for those who are certain that it doesn't exist.

      There appears to be a whole anti-DM subculture. Strong on here. Pretty fucking weird to be honest.

      • by Anonymous Coward

        Because dark matter isn't a thing, it's an observation that our current models don't accurately reflect our observations. Dark matter falls in the same category as the old aether theory; it may exist or maybe we're just wildly wrong. Assuming that it does is a fairly unscientific permits. We've had lovely theories before that turned out to be elegant failures.

        • Dark matter is a model. As long as the model matches the observations, and there isn't a simpler model that does the same, the model is held to be correct.

      • I'll admit that I have my doubts, because it seems to have been postulated simply to make our observations match our predictions and because it appears to be defined as "something that has mass but can't be detected any other way." I wouldn't be at all surprised if somebody were to come up with a theory that explains the data without invoking Dark Matter and managed to prove it by observation. Still, if this does turn out to be Dark Matter, it would satisfy my objections. It's potentially a major step for
        • by iris-n ( 1276146 )

          I don't think there is something wrong with postulating stuff to make our observations match our predictions. This is how science advances. Try explaining the observations of particle accelerators without postulating the existence of quarks, electrons, protons, neutrons, or atoms for that matter.

          The real criterion is whether the stuff you postulate has simple properties or it behaves like fairy dust, magically explaining everything by having several arbitrary properties. I think dark matter falls clearly in

          • by Bongo ( 13261 )

            And I guess, does it lead to a novel prediction which later turns out to be true?

            • by iris-n ( 1276146 )

              Well, that is indeed the gold standard of theory falsification, but I think is not strictly necessary. If I have a theory that is both simple and consistent with all available data that theory is good enough for me.

              But this is a bit beside the point, as we have the famous Baryon acoustic oscillations [wikipedia.org], which were predicted by cosmological models with dark matter, and then observed by WMAP and SDSS.

              • If I have a theory that is both simple and consistent with all available data that theory is good enough for me.

                God did it.

                • by iris-n ( 1276146 )

                  That is an extremely complicated theory. Your "God" concept is not even well-defined. The best attempts to do it involve books with hundreds of pages, that are nevertheless full of contradictions.

                  Particles evolving under the laws of General Relativity, on the other hand, can be described in a few pages. The universe doesn't care about whether your primate brain understands it. There exists an objective measure of complexity - Kolmogorov complexity - and this is what science cares about.

          • The real criterion is whether the stuff you postulate has simple properties or it behaves like fairy dust, magically explaining everything by having several arbitrary properties. I think dark matter falls clearly in the former category, as it can interact only through gravity, greatly restricting what it can do.

            No, that only makes it weirder. If you can only interact with it via gravity, then that differentiates it from all the matter we've actually worked with so far. It requires that we change our understanding of physics. That's not simple.

            • by iris-n ( 1276146 )

              If we would go with "weird" as a criterion to discard theories, we wouldn't have quantum mechanics. Or relativity. Or electromagnetism. Or almost anything that goes beyond our day-to-day experience.

              Of course, one needs a lot of evidence to accept a new kind of matter, as it does require changes to our fundamental theories. We do have such evidence, and we don't have any other theory that can explain it.

            • by dryeo ( 100693 ) on Thursday April 13, 2017 @10:45AM (#54228263)

              We already have an example of weakly interacting matter, namely the neutrino, a particle BTW, that was first postulated to balance some equations (fusion) and then later found in the wild.

              • by ceoyoyo ( 59147 )

                Neutrons too. Half of everything around us is made up of things that would be great dark matter particles if they didn't decay outside a nucleus.

                • by dryeo ( 100693 )

                  Doesn't the neutron interact via the strong force as well? Even the neutrino interacts via the weak force whereas dark matter might not even do that.
                  As you imply, lots of particles don't interact via electromagnetism which might be similar to dark matter. I don't understand the hate/disbelief that dark matter gets as it isn't that different and would be interesting if it exists.

                  • by ceoyoyo ( 59147 )

                    The residual strong force, yes. We'd definitely see neutrons in dark matter proportions in particle searches, but they can fit a lot of the cosmological observations because they don't interact electromagnetically. Both the neutron and neutrino were theoretical objects before they were discovered, just like dark matter particles are today. There's nothing magic about new particles that are hard to detect, make theories work properly, and are later discovered.

                    The neutron was actually discovered just befor

        • Dark matter is hardly the first type or class of particles that was postulated first, and then later demonstrated, so why DM gets such a bad rap when the work going on is no different than the work that went on nearly a century ago to determine the inner workings of the atom, and then later postulating classes of particles like quarks.

          Either Einsteinian gravity has a problem, and it seems to work in all other instances (i.e. gravity lenses). This is a matter of parsimony; Occam's razor as you will. Either a

        • by lgw ( 121541 )

          I'll admit that I have my doubts, because it seems to have been postulated simply to make our observations match our predictions and because it appears to be defined as "something that has mass but can't be detected any other way."

          That's what the "Dark" means - unexplained. We know it exists. We knows it's matter. We know it's "cold", i.e., not moving at nearly the speed of light as neutrinos do. That's all we know.

          The first assumptions about what dark matter might be actually composed of - what sort of particles - haven't played out well. The hope is that dark matter would interact with familiar matter via the weak force, but the first detectors built haven't found anything.

          But there's no real questions that it's "cold matter",

      • There appears to be a whole anti-DM subculture.

        I don't think there are "anti-DM" people here outside of maybe a few wingnuts. There are lots of pro-evidence people here, myself included. The problem with dark matter is that there are at least three possible explanations, none of which have been conclusively ruled out. 1) Dark matter is indeed some form of matter as yet not fully understood, 2) Our measurements are in error somehow, and 3) our models for forces (gravity) are incorrect somehow.

        I have a minor in applied physics so I'm not entirely uninf

        • by iris-n ( 1276146 ) on Thursday April 13, 2017 @01:17PM (#54229287)

          I have a PhD in theoretical physics. Not in cosmology, but I have some contact with people who do work on it.

          So, 2) is astronomically unlikely. The experimental evidence comes from multiple independent sources spanning decades. It consists of simple things such as measuring the rotational speed of galaxies and more sophisticated measurements such as anisotropies in the cosmic microwave background. If you are willing to doubt this kind of evidence you might as well doubt GR itself.

          As for 3), everyone and his dog likes to propose modified theories of gravity that would do away with dark matter. The problem is that reconciling them with the mountain of evidence for dark matter is really tough. The most popular candidates, MOND and entropic gravity are far from being able to do it. Until they do, we're stuck with 1).

          • The experimental evidence comes from multiple independent sources spanning decades.

            Not only independent sources - in the simple sense of "coming from many scientists or groups of scientists" - but also using multiple different distinct techniques from fundamental geometry on different scales (which is behind Doppler measurements of velocities) to sophisticated radiometry leading to the maps of the CMB temperature variations. The data is far wider than just having many different groups using similar techniqu

        • by ceoyoyo ( 59147 )

          Lots of physicists have written about why dark matter is a more attractive option than modified gravity. Measurement error is highly unlikely: the story is consistent across a wide variety of different types of measurements, many of them very basic. Cluster motion and galactic rotation curves require that you believe in the Doppler effect and spectroscopy. Gravitation lensing experiments require that you believe gravity bends light.

          The biggest strike against particle dark matter is that we haven't found

    • by Man On Pink Corner ( 1089867 ) on Thursday April 13, 2017 @06:07AM (#54227303)

      It also means that there's still wiggle room for those who are certain that it doesn't exist

      I found this post on /r/space [reddit.com] pretty convincing. It's hard to argue with so many independent observations.

    • Re: (Score:2, Funny)

      by Rhipf ( 525263 )

      Dark Matter does exist and has been photographed (well actually video taped). It has been broadcast on SyFy and Space (Canadian SciFi channel).

      Oh, not that Dark Matter [imdb.com]. :-)

    • not that the images actually show us Dark Matter.

      Most people are "electromagnetic chauvinists", because all of their senses depend on an electromagnetic field in some way. If a physical phenomenon doesn't create an electromagnetic field, many people refuse to believe that it could exist. However, nothing in physics says that everything in the universe has to be able to create an electromagnetic effect.

      In fact, dark matter does slightly alter electromagnetic fields by bending it over cosmic distances (as well as moving normal matter around). This isn't too

  • Dark matter indirectly measured, dark energy debunked. Astrologers are kicking ass this month!

  • Dark matter does not exist, Dark matter is just the name of a theory that scientists have come up with to describe some anomalous gravity data they got when they looked at how the universe was put together mainly how galaxies interact with each other.

    As they could see something is interacting with the galaxies yet they could not directly detect what is causing the interaction they called it dark and as the general consensus is that in order for this amount of interaction it has to come from somewhere and th

    • Dark matter does not exist

      Dark matter certainly might exist. Or it might be measurement error. Or it might be model flaws. We simply aren't sure at this point. No one can say with any certainty that dark matter does not exist because the data isn't conclusive either way. Yes "dark matter" is something of a placeholder marketing term but it describes what appears to be a very real phenomena. There is some reasonable evidence to suggest dark matter is a real thing but none of it is conclusive at present. We have considerable co

      • by lgw ( 121541 )

        Dark matter certainly might exist. Or it might be measurement error. Or it might be model flaws. We simply aren't sure at this point.

        Not true. We know dark matter exists as certainly as we know the Higgs boson exists, or any other modern physics discovery (all of which rely on may layers of inference between measurement and conclusion).

        We don't know if that is the actual explanation but it's a necessity under current models if we presume they are correct.

        Not true. It must exists for current observational evidence to be correct. To quote Feynman "it doesn't matter how elegant or well-accepted the theory, if it disagrees with observational evidence it's wrong.

    • by iris-n ( 1276146 )

      Spoken with the certainty of someone that knows nothing about the subject. Instead of being proud of your ignorance, you should try to read at least the Wikipedia [wikipedia.org] article about it.

  • Does this Dark Matter Web have a URL?

  • should move to the dark-matter-web, a mesh of such complexity that not even God can find it.

  • Dark matter makes up about a quarter of the universe, but it is difficult for us to detect it because it doesn’t reflect or shine light.

    Or block light. That is the more important property I would think.

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