31 ms·

Dark Matter Doesn't Exist

• deleted 4y ago
  [deleted]
• sethjr5rtfgh 4y ago
  > The implications of this are nothing short of a revision of Einstein’s theory of gravitation. Why the scientific community is in denial about the falsification of the dark matter model (...) This is easy to explain. For Einstein's theory of gravitation you have the experimental evidence of every experiment every done, and against you have one guy with a half-baked argument.
  • santoshalper 4y ago
    Actually, the hard thing about dark matter is that the arguments for it and the arguments against it are both relatively compelling. No matter how this shakes out, we're going to have a very different view of the universe when we finally understand what is really happening.
    • TillE 4y ago
      There aren't really any satisfactory alternatives to dark matter. The question is what exactly is it, and how did it get there.
      • nostrebored 4y ago
        > There aren't really any satisfactory alternatives to dark matter (given current models) Dark Matter is a fudge factor used to account for quite good, but still incomplete physical modeling.
        • atty 4y ago
          “Fudge factor” massively undersells it. For instance, measurements from the bullet cluster are quite compelling that there is significant mass in a galaxy that we don’t directly measure. That’s the definition of dark matter.
    • TremendousJudge 4y ago
      Dark matter has always smelled of phlogistons to me. It's this mystery substance that solves all of our problems, and doesn't make any predictions. I have no idea what a more accurate explanation for the observations would look like, but dark matter can't be it.
      • TillE 4y ago
        It does seem like that, and so there have been many attempts to revise the math to make it fit all known observations. But nobody has been successful, and so dark matter remains, at the very least, by far the best explanation we have. It fits the data.
        • airstrike 4y ago
          > It fits the data. To use an analogy from the world of finance, that sounds like building a Balance Sheet model that "plugs" Retained Earnings so that Assets and Liabilities always balance. Of course it fits the data, its very existence is to explain away the part of the model that doesn't fit the data
          • hannasanarion 4y ago
            Dark matter is not just an imaginary number that fills some holes in math. It is a thing that has been observed. Galaxies can have it or not have it. Galaxies can be separated from it in collisions. You can't be separated from something that doesn't exist.
        • TremendousJudge 4y ago
          This article has introduced me to "Modified Newtonian dynamics", which is a field of study I didn't know existed. The premise is pretty obvious now: Newton was pretty cool and all, but he wasn't right about high acceleration environments. Why then should we presume that he was be right about low acceleration environments, when the observations don't fit the predictions? The fact that nobody has come up with an answer doesn't mean there isn't any, and at least these people are actively trying to come up with one. I understand why the author appears to be very frustrated -- I'd be frothing-at-my-mouth angry in his position.
    • citizenpaul 4y ago
      >the arguments for it We don't understand why our numbers don't add up so we made up a number to explain it is "compelling" to you? Dark matter has always reeked of "ether" to me. I looked into some of the alt science on this a long time ago. There is a compelling case that our model of gravity is wrong. Fortunately gravity is such a weak force that at small ie solar system scales it doesn't matter. Which is why we can launch satellites around the system. However the failure shows at large scale like galaxies.
      • hannasanarion 4y ago
        Dark matter isn't just a made-up number. It's an observed phenomenon that MOND and other modified-gravity theories cannot explain. It is an observable fact that dark matter is a distinct substance from baryonic matter. Modified gravity is thoroughly disproven by the many galaxies that have been discovered that have been separated from their dark matter[1], or seem to have never had any in the first place [2]. A galaxy can't be separated from, or be lacking in, something that doesn't exist. Any attempt to dismiss dark matter entirely without addressing this highly conclusive evidence is not valid. 1. https://www.wikiwand.com/en/Bullet_Cluster https://www.wikiwand.com/en/Bullet_Cluster 2. https://www.inverse.com/science/dark-matter-in-galaxies https://www.inverse.com/science/dark-matter-in-galaxies
        • citizenpaul 4y ago
          Its been a very long time since I looked at any of these stuff and I'm certainly not a subject matter expert. I just remember reading about it and the entire idea of dark matter and dark energy came from the fact that the math models they had at the time didn't add up. They needed a way to rectify the math and they did it by saying well if we put this LITERALLY made up number in the equations everything balances out. Then they made up the explanation as to why this number needed to exist as "dark matter/energy" There have been mountains of research made trying to prove this since then that muddy the water of how flimsy the origin was.
  • the_af 4y ago
    Plus accusing the mainstream scientific community of "blindly and religiously believing in [...]" is a page taken directly from the Crackpot Index [1]. "They are suppressing my work!" "They do not want you to read this!" Etc. [1] https://math.ucr.edu/home/baez/crackpot.html https://math.ucr.edu/home/baez/crackpot.html
    • yinser 4y ago
      That's a pretty fun index. If you removed the bias of accepting the current cosmological model as consensus and read it like it was submitted by a grad student how many points would the dark matter & dark energy model accrue? Is it logically consistent to propose a model that requires such a large adjustment by the inclusion of variables that have never been experimentally proven to exist? Does this model rest on the laurels and works of Albert Einstein? "10 points for each new term you invent and use without properly defining it." Do dark matter and dark energy not qualify here? IANAP (physicist) but using this index it's hard not to imagine another place in the multiverse where this dark energy/matter cosmological model receives a high score on this rubric.
      • the_af 4y ago
        Well, the Crackpot Index is obviously tongue in cheek, but also born out of frustration, I think. It must get tiresome for scientists to listen to cranks trying to "disprove" established science with bizarre theories and a complete disregard for the literature. You can address one, two, three of these people, but it soon becomes a bother and you're tempted to write the Index instead. I agree it's probably very difficult to tell really novel and paradigm-shifting theories from the ramblings of cranks. I suppose the Dark Matter model scores highly in some items of the Crackpot Index but very low in "the government is trying to suppress this", "everything they told you is a lie", and also the scientists who proposed it understood the established science and didn't randomly disregard it. I think the "conspiracy" aspect is what sets a crackpot apart. Again, it's possible that a person is a crackpot AND he/she is also right about a particular theory!
        • notpachet 4y ago
  • lisper 4y ago
    > every experiment ever done But that is manifestly untrue. If every experiment confirmed Einstein we would not even be talking about dark matter. > one guy with a half-baked argument But that "one guy" happens to be an expert in the field. And his argument sounds fully baked to me.
    • munchler 4y ago
      Dark matter doesn't contradict general relativity, so it's entirely plausible that a) every experiment confirms Einstein, and yet b) we still need dark matter to explain some observations.
      • lisper 4y ago
        "Dark matter" is a synonym for "some unknown stuff that causes experiment to disagree with theory based on what we currently observe." It's not dark matter per se that contradicts GR, it is the experimental observations that require dark matter to be postulated in the first place that contradict GR.
        • munchler 4y ago
          No, there's nothing in the dark matter hypothesis or observations that necessarily contradicts GR. However, it's true that some other theories that claim to explain the dark matter observations are in conflict with GR, which is why those theories are received very skeptically.
          • User23 4y ago
            Which is odd, because by far our best experimentally verified theory is also in conflict with GR. Our measurements for QED are orders of magnitude more accurate, so I'm inclined to believe GR is the incorrect theory.
            • adgjlsfhk1 4y ago
              Some of our measures of QED are very accurate (10 decimal places give or take), but the measurements QCD are much more complicated and the theory doesn't produce nearly as clean values. Also, there are purely QED experiments (muon G2 for example) where there are some serious contradictions.
  • yinser 4y ago
    The theory of gravitation is not at question here, it is in fact the basis for proposing the existing of some yet-unseen matter to account for why the observed galaxies behave. Someone proposing that there is no such thing as the thing we have never observed is... a pretty "baked" argument.
  • aranchelk 4y ago
    There are other hypotheses competing with dark matter which have revised models of gravity, it’s not just one guy: https://en.wikipedia.org/wiki/Entropic_gravity https://en.wikipedia.org/wiki/Entropic_gravity https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics
  • jbakhos 4y ago
    I would like to toss my own idea into this discussion. This idea incorporates a mechanism that would explain why gravity might slightly deviate from Newtonian and/or GR in some circumstances. This paper also adapts GR in such a way that it is consistent with galactic rotation rates, the anisotropies of the CMB, and cosmological expansion -- while showing that the simple operation of gravity is the cause of each of these phenomena. Cyclic Gravity and Cosmology (CGC) predicts that there are discrete specific sizes allowable for macro-objects. The instability of Bennu and the fact that it behaves more like loosely held scree rather than a compact mass -- is an example of a mass that is not exactly at one of the discrete allowable sizes. Please also refer to the link I included wherein I uploaded a video simulation of the formation of a solar system using this type of force law. (This is in section 18 of the paper) I would greatly appreciate any comments on this idea. Copies may be downloaded here: https://vixra.org/pdf/2203.0032v3.pdf https://vixra.org/pdf/2203.0032v3.pdf
• boosteri 4y ago
  I wondered if this was a spin on this-(insert noun)-does-not-exist
  • samstave 4y ago
    Finland
    • oaiey 4y ago
      That is dark man
      • BubbleRings 4y ago
        It is just an internet joke. https://en.m.wikipedia.org/wiki/User:Herostratus/Finland_does_not_exist https://en.m.wikipedia.org/wiki/User:Herostratus/Finland_doe... Also https://www.cbsnews.com/news/birds-arent-real-origin-60-minutes-2022-05-01/#app https://www.cbsnews.com/news/birds-arent-real-origin-60-minu...
• scotuswroteus 4y ago
• oniony 4y ago
  I wanted to read more about this 'Mond' thing and found this article <https://phys.org/news/2022-07-dark-ditch-favor-theory-gravity.html https://phys.org/news/2022-07-dark-ditch-favor-theory-gravit...>, which seems to be well written and at my level. And this wikipedia article, <https://phys.org/news/2022-07-dark-ditch-favor-theory-gravity.html https://phys.org/news/2022-07-dark-ditch-favor-theory-gravit...>, seems to give a more balanced appraisal.
  • lief79 4y ago
    You included the same link twice. I'm guessing you wanted this one: https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics
• becquerel 4y ago
  I'm extremely skeptical of a 'simple test' which proclaims to overturn decades of scientific knowledge. Why did it take until 2022 for someone to think of this, and not a hungry grad student in the 80s looking to make a name for themselves?
  • greenthrow 4y ago
    Read the article. It isn't a new claim.
    • kazinator 4y ago
      So why isn't hasn't it been accepted long ago?
      • sethrin 4y ago
        Because it fails to account for all DM observations.
        • kazinator 4y ago
          The statement "phlogiston doesn't exist", by itself, also doesn't acccount for all observations for which phlogiston adherents require the existence phlogiston.
          • sethrin 4y ago
            This is a low-brow dismissal without basis in fact. At the moment, multiple independent lines of evidence suggest that DM is real. There are no observations which contradict DM. Any competing theory must explain the same observations, which means that it will necessarily be a theory of dark matter. Dark matter is a real phenomenon, whether or not you choose to acknowledge its reality.
        • deleted 4y ago
          [deleted]
      • 4y ago
• ajross 4y ago
  Research seems to have calculated a bound on the large scale distribution of dark matter that shows it doesn't exist in extragalactic halos. Article makes hyperbolic claims that "dark matter doesn't exist". This is junk, sorry. And that article makes me deeply distrust the otherwise-reasonable-seeming research.
• munchler 4y ago
  > a model universe in which the normal matter we see around us in the form of atoms makes up only 5% of all the energy in it. About 20% is made up of exotic dark matter particles > for each gram of normal matter there are 25 grams of the exotic dark matter 20% is four times 5%, yet there is 25x difference in mass? How does that work?
  • tom-thistime 4y ago
    Yeah the article seems to get some simple percentages wrong early on. (The downvotes on the comment above are incomprehensible, but that's downvotes for you.)
  • ncmncm 4y ago
    They are talking about dark matter in one instance, and dark matter + dark energy in the other. So, no contradiction.
• BillSaysThis 4y ago
  Of course it does -- https://en.wikipedia.org/wiki/Dark_Matter_(TV_series) https://en.wikipedia.org/wiki/Dark_Matter_(TV_series)
  • Octoth0rpe 4y ago
    Even better because the article link is on a .tv domain :)
  • airstrike 4y ago
    Now all we need to find is its elusive 4th season...
• fullstackchris 4y ago
  Armchairing here, but what exactly about Einstein's theory doesn't correspond with this so called "current cosmological model"? This article doesn't really state what, exactly, needs to be "revised". Because, as someone said farther up in the comments, as far as I know, Einstein's theory has been confirmed against every experiement ever done.
  • colechristensen 4y ago
    On galactic and larger scales galaxies move and form as though there is a lot more mass out there than we can see. I forget the exact figure but something like 20x as much. Either you have to patch your gravity theory or assume there’s a bunch of stuff which interacts gravitationally but barely or not at all with electromagnetism.
    • lumost 4y ago
      Has this observation been tested against frame dragging? What if supermassive black holes rotate much faster than we except?
      • colechristensen 4y ago
        I'm sure that every iteration of "have you tried X" has been tried, which is why the most popular theory is "there's a bunch of stuff we can only see through its gravitational effect".
      • raattgift 4y ago
        Central black holes' spins don't drive their host galaxies' rotation. * Elliptical galaxies exist where the rotation curve almost exclusively measures radial motion of blobs of gas (radiating specific wavelengths, whose redshift we can compare with other parts of the same galaxy), and sometimes other bright objects with characteristic spectra, which move outwards and inwards on an elliptical orbit; these galaxies may not spin around an axis, and may not even have anything like an equator. The anomaly is that the difference in these rising-and-falling orbits' is not as large as expected -- the outer reaches are dimmer, less dusty, and less gassy than the denser inner reaches, so there is less ordinary mass out there, but this reduction in mass density is not reflected in the orbital speeds; * In discoid galaxies (spirals, etc.), the spin-axis of the central black hole may point at any angle relative to an axis through the galaxy centre, perpendicular to the thin disc; the polar jets of black holes can even blast mostly into the thin disc, rather than mostly out of it; the polar jets are indicative of the spin-axis of the central black hole; * Galaxies may have more than one central black hole, especially the larger ellipticals. These central black holes typically do not have their spin axes point in the same direction, and where the spin axes are remotely close to perpendicular the black holes might not all spin in the same direction; * Some central black holes are gargantuan, some are petite (ours is small, especially compared to the number of stars in the Milky Way), and some are apparently absent, but the rotation-curve anomalies appear to be very similar nevertheless. That said, active central black holes -- "Active Galactic Nuclei" (AGN), of which quasars are a species -- can blow tremendous amounts of matter out of the central regions of their host galaxies, and that can alter the orbital speeds of gas and dust clouds in those galaxies generally, and much more so the behaviours of X-ray-bright gas and dust they shoot outwards into extragalactic space. AGNs can switch from very bright to essentially off, and as far as we can tell the switch-off of AGNs does not cause the rotation curve anomalies to relax. (Our extremely quiet central black hole may have been an AGN perhaps as recently as millions of years ago. <https://en.wikipedia.org/wiki/Galactic_Center#Gamma-_and_X-ray_emitting_Fermi_bubbles https://en.wikipedia.org/wiki/Galactic_Center#Gamma-_and_X-r...>). Frame dragging by the rotation of central black holes in AGNs may be seen in the corkscrewing of their jet emissions: Galaxy 3C 348 shows this clearly <https://duckduckgo.com/?q=3C+348+galaxy&iax=images&ia=images&iai=https%3A%2F%2Fwww.physicsforums.com%2Fattachments%2Fherc-a-jpg.243430%2F https://duckduckgo.com/?q=3C+348+galaxy&iax=images&ia=images...> as does the more popular M87 <https://apod.nasa.gov/apod/ap011101.html https://apod.nasa.gov/apod/ap011101.html> These jets are very bright in some characteristic wavelengths (radio in 3C 348, X-Rays in M87), but they're much sparser than the starry regions of their respective galaxies. These two galaxies are large ellipticals, and their jets do not align with anything like a central rotational axis as in a spiral galaxy. The screw displacement related to frame dragging happens in the near region to the source black holes. Anomalous gas-cloud rotation curves are found in the far region, at the outer edges of galaxies.
• greenthrow 4y ago
  This article is not very good. It conflates disproving specific models that use dark matter with disproving dark matter itself.
  • horsawlarway 4y ago
    I would place this comment in the same bucket :P You can't "prove" that something doesn't exist. And dark matter is simply a big fat "????" inserted into our math to make our equations match what we see. I think it's fair for them to state that dark matter doesn't exist, in the same way that I can fairly confidently state that "The christian god" does not exist. Doesn't explain how we got here, or what actually needs to change to make our equations match our observations, but it's a reasonable stance to encourage folks to stop spending time on an unlikely solution (even if it so far produces the best model we have).
    • ziddoap 4y ago
      >an unlikely solution (even if it so far produces the best model we have). If it is consistently producing the best model, why is it an unlikely solution? What would be more likely than the model which produces the best match to what we observe?
      • horsawlarway 4y ago
        Well - I would say this article is trying to discuss why it would be unlikely - Namely, most of the experiments we can find to experimentally test for dark matter fail. Just because a model fits our current data doesn't make it correct (honestly - my strong stance is no model is correct, but some models are useful, and some more useful than others). Epicycles were a fantastic explanation for the timing and movements of planets appearing in the sky - They were the best model we had for hundreds of years, but the model was also utterly incorrect. It wasn't until an almost rock solid assumption (that earth was the center of everything) was assaulted by Copernicus that we developed much more robust models. I find it fairly interesting that epicycles were also an attempt to explain a observational data that was very hard to fit into current models. There's a fairly straight parallel to dark matter here. I find it very compelling that we have a foundational assumption in our current model that isn't true, and that's why we're offsetting everything with dark matter to make the math line back up with reality.
• kazinator 4y ago
  What if most of the dark matter surrounding an object is moving in more or less the same direction at the same velocity, being in the same neighborhood? The Chandrasekhar-friction-based objection to dark matter seems to assume that dark matter must be a kind of soup that is standing still, while only the galaxies (or whatever objects) wade through it.
  • ncmncm 4y ago
    If it had the same distribution as visible matter, it wouldn't be "dark". There would just more matter. It is that it is not doing the same as visible matter that makes it useful to patch in for otherwise inconvenient observations. Dark Matter advocates, if honest, should be trying to patch up their definition to account for all these observations. Studiously ignoring them is unscrupulous.
• ape4 4y ago
  Dark Matter gravitational lensing seems pretty convincing. https://www.nasa.gov/content/discoveries-highlights-shining-a-light-on-dark-matter https://www.nasa.gov/content/discoveries-highlights-shining-...
  • april_22 4y ago
    Also, the research done regarding weakly interacting massive particles has been very interesting to follow the past couple of years https://you.com/search?q=Weakly+Interacting+Massive+Particles https://you.com/search?q=Weakly+Interacting+Massive+Particle...
  • ncmncm 4y ago
    We have gravitational lensing, but that cannot save DM from other observations fundamentally incompatible with its premise. Clinging to a single dominant theory is religious orthodoxy, not science. The essence of science is, "we don't pretend to know what we don't". There is plenty we do, that doesn't depend on DM.
• bena 4y ago
  At this point, I consider "Dark Matter" to be a substitute for "Shit We Don't Know About". We know, roughly, how gravity and all these forces are supposed to behave. Certain celestial bodies don't follow those rules according to what we know about both the rules and those bodies. So there's something we don't know about there. Either the body or the rule is missing something. If it's the body, then there's a whole mess of matter that's just imperceptible to our current methods. It is "dark" to our observation.
  • stjohnswarts 4y ago
    Kind of smells like blackholes and we're pretty sure that they exist.
• ziddoap 4y ago
  Last I understood (I am not an expert) MOND and related theories fails to explain certain observed phenomena, and goes against other experimentally verified laws/phenomena. PBS Spacetime covers this topic in several videos, a good one being [1]. Matt (the host, an astrophysicist), describes what MOND (and other alternative theories, like relativistic-MOND) needs to do but haven't done yet: 1. Give the right answer in more than one special case. MOND may describe a few situations accurately, but it does not describe all situations where we have evidence for dark matter. Only some. 2. Consistent with other known laws and theories that are experimentally verified. According to Matt and others, MOND is not consistent with existing laws such as conservation of energy or angular momentum. 3. Make testable predictions beyond what it was tuned for. Am I missing out on some extraordinary development in MOND and/or MOND-like theories that occurred recently? [1] https://www.youtube.com/watch?v=0sTBZ2G4vow https://www.youtube.com/watch?v=0sTBZ2G4vow
  • jvanderbot 4y ago
    The article is not about MOND, it is about the falsification of Dark Matter. They do advocate MOND, but the main takeaway is right up front: > The current cosmological model only works by postulating the existence of dark matter – a substance that has never been detected, but that is supposed to constitute approximately 25% of all the universe. But a simple test suggests that dark matter does not in fact exist. If it did, we would expect lighter galaxies orbiting heavier ones to be slowed down by dark matter particles, but we detect no such slow-down. A host of other observational tests support the conclusion: dark matter is not there.
    • canjobear 4y ago
      So if DM is falsified and MOND is unworkable, what should scientists do? Just admit that they have no idea what's going on, but it looks a lot like missing mass? Oh wait, that's the definition of dark matter.
      • StanislavPetrov 4y ago
        >Just admit that they have no idea what's going on, but it looks a lot like missing mass? The way I see things, the much more prevalent attitude is, "we have a good idea of what's going on, we just haven't been able to confirm our confident assessments with objective data". Very few, if any, prominent people in the field admit, "we don't have any idea what's going on, it is all baseless conjecture that might pan out if 75% of the universe is made of some invisible stuff that we haven't been able to detect in 4 decades despite our best efforts". I'd like to see a paradigm shift from, "we have a good understanding of how things work, now we just need to detect the invisible particles that make all of our formulas work" to "we have really have no idea what is happening, but here is some wild speculation that is the best we can come up with". A lot of the "dark matter" debate reminds me of the Alzheimers/amyloid situation. Groupthink develops among the establishment in the field, based on very little (if any) objective proof, which ends up discouraging and marginalizing those who pursue other theories.
• untilted 4y ago
  (Disclaimer: am particle physicist, but not a cosmologist) For a bit of context, see Sec. III.6 of https://arxiv.org/abs/2105.05208 https://arxiv.org/abs/2105.05208 ("Challenges for ΛCDM: An update", where ΛCDM is the "standard model of cosmology"). The linked article refers to _known_ problems that this model has describing small scale structures. That dark matter doesn't exists seems like a non-sequitur to me.
• incomingpain 4y ago
  It is true that it has never been observed and is hypothetical. However, we have observations which break the rules. https://en.wikipedia.org/wiki/Galaxy_rotation_curve https://en.wikipedia.org/wiki/Galaxy_rotation_curve The thing to me, why do we assume kepler's law applies to galaxies? It has only been proven in relation to the solar system. Perhaps it has been proven to work for the exoplanets in other systems? Also what exactly is dark matter? Is it some exotic unproven god or is it just dust, hydrogen that just doesnt glow or light up? What about our observations are just wrong? What if we haven't adjusted our observations for https://en.wikipedia.org/wiki/Local_Interstellar_Cloud https://en.wikipedia.org/wiki/Local_Interstellar_Cloud and thusly we are slightly off because of some latent glow from the local cloud? Or perhaps even going further and being in some transition to the neighbour cloud is throwing observations off.
  • sethrin 4y ago
    There are multiple independent lines of evidence for DM. Your questions would be answered by reading the Wikipedia article on Dark Matter: https://en.wikipedia.org/wiki/Dark_matter https://en.wikipedia.org/wiki/Dark_matter
    • incomingpain 4y ago
      Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe.[1] We dont have the answers for anything here.
      • sethrin 4y ago
        > We dont have the answers for anything here. This very clearly must hold true for any "we" which refuses to read past the first line of an encyclopedia article.
• causi 4y ago
  If someone were to ask me I'd say I embraced the scientific consensus that dark matter is real, but in my heart of hearts I have to admit that it smells like phlogiston and aether to me, and its lack of falsifiability is not something I can ignore.
  • yccs27 4y ago
    About the falsibility - we have a paper with a method to disprove dark matter right here. There are many different cosmological observations which demonstrate deviations between expected and measured gravity, and they are only getting more numerous. If one theory can explain them all, that would already be a big accomplishment. Dark matter seems to explain more than any competitor, but as I understand it no theory seems to fit perfectly.
    • cedilla 4y ago
      We have the claim of a refutation here, but one that is obviously weak. If your only explanation of why your toy theory is rejected by everyone else is collective, universal delusion you've already disproven yourself. No theory fits perfectly, but that is what we expect in a world of imperfect knowledge.
      • yccs27 4y ago
        The science of their method to disprove dark matter is really pretty good. The problem is how they present other scientists as foolish for holding onto dark matter theory. More researchers should definitely take a look at the evidence. There are some strong reasons why dark matter is the favored model, and it needs to be a strong refutation to rule it out. If other contenders like MOND didn't also have significant problems of their own, people would also be more eager to lend them credibility instead of dark matter.
  • zinclozenge 4y ago
    This is the same situation as when special relativity was being developed. The equations for the mechanical theory of the aether looked exactly the same as the equations for special relativity. Similarly any modified gravity theory will be identical to a dark matter theory, except for the motivating principles. So far modified gravity theories can’t explain everything. That and they would have to integrate with general relativity for which evidence is only getting stronger.
• celeritascelery 4y ago
  I will start by saying that I know very little about theoretical physics so I could be totally off here. But to me the idea of dark matter feels a little like the theory of ether[1]. Basically we observed a behavior we couldn’t explain, so we create a new invisible substance that permeates the cosmos to fill the hole in our scientific world view. It turned out that we just didn’t understand the science well enough, and there was no ether out there in the first place. Dark matter feels like too convenient of an explanation given that we have never detected it. [1] https://en.m.wikipedia.org/wiki/Aether_theories https://en.m.wikipedia.org/wiki/Aether_theories
  • at_a_remove 4y ago
    You have this entirely backward. Ether was introduced because, previously, all other wave motion was waving something. It was standard issue. Waves in the ocean? Must be waving something. Waves in air? Must be waving something. Positing that there was nothing there "waving" would be the new thing. Second, introduction of a "thing," only to find out that it is real is quite common. Witness the neutrino -- originally just a placeholder to make the math work.
    • kortex 4y ago
      How is that any different? Sounds like "dark matter was introduced because, previously, all other matter interaction was pulling on something". It walks invisibly but quacks like matter (lensing, galaxy geometry, etc) so we call it dark matter. It's all the ways in which it doesn't act like matter which make it interesting.
  • taylodl 4y ago
    It's exactly like the theory of the ether. It was the fleshing-out of that theory that made physicists doubt its veracity - a substance must permeate all space, be more rigid than steel yet not impede planets orbiting the sun? Really? The Michelson-Morley experiment put the final nail in ether's coffin - but there were already a number of nails. On the upside, it led to great physics! Let's hope we'll be able to say the same for Dark Matter.
• rsaarelm 4y ago
  How do the recently discovered rare galaxies that look like they have no dark matter fit in with the idea that instead of clumpy stuff that can end up distributed oddly, we're dealing with a universal physical law? Shouldn't the physical law be the same for all galaxies?
  • saberdancer 4y ago
    I'm no physicist but if you want to be cheeky, you introduce a "rare dark matter" to a MOND model and explain away those rare instances. My point is, dark matter explains the observations by being very flexible. There can be any amount of dark matter to fit the observations.
• sega_sai 4y ago
  Astrophysicist here. This is the same shtick from from a known anti-DM guy. A few points. * DM particle haven't yet been found. * The current best theory of the structure formation and galaxy evolution involves dark matter and critically depend on it to reproduce observations. * There is a broad variety of Dark matter models that are consistent with simulations. * It is possible there is some theory that somehow explains everything without the need of dark matter, but it doesn't exist (now), and very likely it would work effectively like dark matter. Without such theory, claiming DM doesn't exist is simply stupid IMO. * There are a few cases where you can find tensions with the existing DM based paradigm. I.e. the is test pointed in the article involving galactic bar in the paper "Fast galaxy bars continue to challenge standard cosmology". Note the toned down title. In this paper they just compared one specific feature of galactic disks in the simulations to the data and show that it doesn't match. I'd argue there are many reasons that could be the case that doesnt' involve killing DM. The same applies to other tensions. * A final point. Even Modified Newtonian Dynamics theories require DM, because without it you cannot form enough structure early in the universe (as dark matter start to collapse earlier) and is essential to reproduce the amount of structure we see in the cosmic microwave background.
  • replygirl 4y ago
    dark matter - the new epicycle?
    • croes 4y ago
      Only if we find a better explanation.
      • kloch 4y ago
        This is a constant bug/feature of human thought. When we try to see beyond the limits of our technology we find it irresistible promote explanations that can't be proved yet. Often these placeholder theories turn out to be complete nonsense (epicycles). Often they are incredibly convincing (Dark Matter), and sometimes they even turn out to be mostly correct - so this process is generally a good thing. Where we run into trouble is by assigning too much credence (or too little skepticism) for that which has not been proven yet. This can be counter-productive as it may stifle research into other areas (in this case gravity). When we take the "best current theory" and deride skeptics of it to the point that it discourages other areas of investigation, that's a bug, not a feature. Our current understanding of gravity is woefully inadequate, as shown by our inability to reproducibly measure the gravitational constant as well as we should be able to with current technology. The flyby anomaly is another example where DM does not help. I hope that the current popularity of DM does not stifle research into gravity.
• NHQ 4y ago
  Dark matter is all hand waves.
• lamontcg 4y ago
  I'd really either like someone to find a new dark matter particle or to fix most of the problems with MOND.
• neosat 4y ago
  Can someone with the appropriate background please confirm or refute? "But a simple test suggests that dark matter does not in fact exist. If it did, we would expect lighter galaxies orbiting heavier ones to be slowed down by dark matter particles, but we detect no such slow-down." Is that hypothesis correct? (i.e. would we expect lighter galaxies orbiting heavier ones to slow down if dark matter exists) If it is correct, and we don't observe that effect, would it not be a very strong argument refuting the existence of dark matter? For folks mentioning this as a "crackpot" or "anti-dm" theory, is the strong claim that the hypothesis is incorrect?
  • deelowe 4y ago
    I've read nearly every comment here and no one seems to have an answer... It is a very convincing argument, to be honest.
    • cryptonector 4y ago
      > and no one seems to have an answer Especially DM proponents!
    • thurn 4y ago
      There are phenomena in the universe that, for example, general relativity does not predict correctly. Is your conclusion that we should discard any useful theory which ever fails to match an observation? Would someone who relied on Newtonian dynamics 100 years ago likewise be incorrect to do so because it failed to explain many aspects of planetary motion?
      • deelowe 4y ago
        No one is suggesting anything should be discarded. Just that the null hypothesis be tested.
    • neosat 4y ago
      Yup, no one still seems to have an answer to a simple, straightforward question, and the lack of any convincing counterargument makes it even more convincing.
• Cryptonic 4y ago
• izzytcp 4y ago
  Germans … always be party pooping. Let us have fun, we don’t always need to be correct.
• deanCommie 4y ago
  Can someone with an actual physics background clarify my understanding: My interpretation of "dark matter" isn't that it's literally "matter" that is invisible and we are trying to find a way to detect it and interact with it. Rather it's just a shorthand term that explains our math. We detect gravity. The only thing that we know that makes gravity is matter. We detect more gravity for the amount of matter we see. Therefore we call what we cannot detect "dark matter". But that's it. We have no other semblance that it is somehow "matter". We might as well call it "Unknown Gravity Generator". Is that right or am I off base? If I'm right, then could it just be as simple that gravity Works Differently at galactic scales much the same way that everything works differently at quantum scales and relativistic (ie high velocity) scales? And as such, we don't really need to "find" dark matter, but rather we just need to find out exactly under what circumstances the equations change - much as Einstein did for relativity? And it's a super hard problem because while we can make things move at the speed of light in a lab, we can't really give something galactic mass in a lab, and observing galactic-masses in the real world on a human scale is very hard as any relevant measurements would require multiple lifetimes to observe (hypothetically) If I'm wrong, in what other ways is dark matter "matter-y" that makes it a useful term? And do scientists believe there is a chance we could actually be able to "generate" it an experimental environment?
  • davrosthedalek 4y ago
    Well, to some approximation, in general relativity, matter=gravity generator. (And dark=not interacting with photons enough that we can see it)
  • sethrin 4y ago
    This theory is called MOND. It is generally considered to have fatal issues with observations: https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics#Responses_and_criticism https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics#Re...
  • raattgift 4y ago
    > [how] is dark matter "matter-y" ... ? Its characterizing bulk behaviour is that dark matter exerts a pressure on galaxies immersed in it, effectively squashing them inwards (or, if you like, preventing discoid galaxies from flying apart as they spin quickly). Under <https://en.wikipedia.org/wiki/Dimensional_analysis https://en.wikipedia.org/wiki/Dimensional_analysis>, pressure has dimension L^{-1}MT^{-2}, which is the same as energy-density. Energy-density is encoded in the (symmetric, gauge-invariant, conserved, (0,2)) matter tensor of the Einstein Field Equations of General Relativity. Among other things this preserves notions that matter/energy cannot be created or destroyed, only converted from one form to another. It is the microscopic constitution of the bulk energy-density, and the details about how or if it can be converted into photons or some other radiation, or other types of matter, that is not known, although the bulk behaviour imposes numerous constraints. As with all matter in General Relativity, dark matter is subject to the strong equivalence principle, just like laboratory Cavendish experiments, or binary or triple pulsar systems, or in galaxies' peculiar motions within galaxy clusters. Finally, your "as simple that gravity Works Differently at galactic scales" is a rejection of the Strong Equivalence Principle, and also raises the question of the (unknown) microscopic details of how the inverse square law holds up so well everywhere except the edges of many known galaxies. Typical approaches involve a new long-range ("fifth") force that in bulk effectively applies a tension on the outer reaches of galaxies where MOND transitions from the familiar 1/r^2 inverse square law for gravity to the slower-decaying 1/r law. Tension has the dimensions of negative pressure, so essentially rather than outside-the-galaxy dark matter pushing the outer gas clouds and stars inwards, we have something inside the galaxy reaching out and pulling the same gas clouds and stars inwards. One is then left struggling to do anything other than to describe the microscopic behaviours of a field that sources this negative pressure, and making that field denser somewhere towards the middle of galaxies.
• rob_c 4y ago
  Big claim, one test (based on their model(, fails to explain gravitational lensing phenomena without a terra centric set of spinning wheels in theory...
• throwaway892238 4y ago
  Stupid person here. Couldn't DM just be like gauge bosons (no mass) and also not carry any other force that would "slow down" other matter?
  • davrosthedalek 4y ago
    Needs mass -- that's what couples to gravitation, and that's the original reason we think there is DM.
• cratermoon 4y ago
  To people saying the Dark Matter sounds like aether, phlogiston, or miasma, I have to wonder. Dark Matter is simply something that isn't affected by electromagnetic fields. We already have particles that don't interact with one or more forces. The weak interaction only affects fermions and antifermions. The strong force only affects quarks, photos are massless, etc. What's so hard to accept about a particle that doesn't interact with electromagnetism, and thus neither absorbs nor emits light?
  • davrosthedalek 4y ago
    Not to forget that neutrinos also do not have an electric charge, i.e. also do not couple to photons directly.
    • cratermoon 4y ago
      There's probably more, I'm not up on all the particles. My thought is that a) a particle that only interacts with gravity is not prohibited by the Standard Model and b) our inability to detect (yet) such a particle is not proof it doesn't exist.
  • ncmncm 4y ago
    The issue is not whether it acts like regular matter. At issue is, rather, whether observations consistent with DM as formulated should be privileged over others that are not. Current behavior of cosmologists is that inconvenient observations should not count, and need not be paid any attention. That is why the authors bring up sociological explanations for cosmologists' behavior. It is not scrupulous science.
  • saberdancer 4y ago
    It's not hard to accept existence of dark matter, but it is an extremely flexible, hard to prove answer. If you see a galaxy that rotates differently, you say it has more or less dark matter. It sounds like an easy answer.
• exabrial 4y ago
  It’s not completely impossible that something doesn’t interact with the electromagnetic force… somewhere we’re missing something something.
• charles_f 4y ago
  I know nothing of astrophysics and my opinion counts for shithole. But DM has always reminded me of aether (https://en.m.wikipedia.org/wiki/Aether_(classical_element) https://en.m.wikipedia.org/wiki/Aether_(classical_element)) - a magical element that we add to current understanding of physics to correct for errors caused by missing knowledge. DM sounds so magical that it feels like an unknown force akeen to gravitation. But once again, I don't know anything about this, so, who cares.
• gauddasa 4y ago
  It's amazing that even theoretical physicists are coerced into believing in superstition by mathematics.
• benreesman 4y ago
  As a complete physics layperson, I can’t comment with any authority on the subject matter. What I do have is a metric fuckton of experience with incentives and mechanism design in technical fields: and mainstream physicists have been talking like people who have bonuses linked to specific outcomes for decades. The moving goalposts around falsifiability, the too-coincidental synergies between supersymmetric-style (and there for string world) stuff and missing mass (dark matter), the growing group of highly-qualified skeptics, the curt public dismissals everything from LQG to constructor stuff to MOND as beneath refutation, the popularizers who go on PBS and don’t even acknowledge a debate. And the alternative explanation, that it takes so long to learn this stuff that your career is over if Dark Matter or String Theory turns out to be hokum? Yeah, that scans.
  • jollybean 4y ago
    This is very cynical but there's some truth to it. I also believe that it's less conscious. Once people accept an idea they're conditioned to think of it as true, and then when jobs and institutions revolved around that it amplifies aberrations. Maybe String Theory is total bupkiss, a lot of people are going to have a hard time with it. But with this subject we're at least working with observable data ...
    • cryptonector 4y ago
      Network effects can yield delusion and fraud without the participants consciously trying for it.
  • ncmncm 4y ago
    Not so different from Alzheimer's researchers continuing to give one another federal grants for ways to block production of amyloids decades after it has been shown to be a dead end. One wonders what all those amyloid biochemists can do with themselves once amyloid grants finally go away.
  • irjustin 4y ago
    To me, this is the cost of discovery. Just like a game of chess, you have to spend a lot of energy/cost thinking about lines that will not come to fruition to find the correct path. Poor Alzheimer's research was/is stunted for a few people at the top pushing the wrong path. We'll see if that's the case for DM vs MOND vs something else. Money will always be distributed to the wrong areas, but as long as you believe the human race to exist far into the future, it will eventually work itself out.
• jalapenos 4y ago
  I've had this theory for a long time that maybe the missing mass that dark matter is supposed to account for is actually antimatter (which also should theoretically exist in equal quantities to matter), due to antimatter actually having antigravity, and therefore dispersing thinly throughout space rather than clumping together. Can someone knowledgeable in physics set me straight on the plausibility of this theory?
  • hexomancer 4y ago
    I am not knowledgeable in physics, but I think dark matter is supposed to be unaffected by electromagnetic forces (hence why it can't be seen) which is definitely not true for antimatter.
  • cryptonector 4y ago
    Antimatter isn't dark. It interacts with matter just fine -- too fine!
• blinding-streak 4y ago
  As a lay person on this topic, a question. I've always heard that string theory was an untestable theory that academia was obsessed with for decades, and research on it soaked up a large amount of academic budgets and grant money. And was ultimately fruitless. (Again, I'm on the outside looking in, I don't work in the field so I'm not 100% sure if this is accurate) Is dark matter in the same boat as string theory was, from a grant money and research standpoint?
  • toast0 4y ago
    There's been concrete expirements looking for dark matter (not yet found). That advances science, even if unfruitful. I don't think there have been any expirements re: strings? So it advances philosophy, but not really science yet.
    • blinding-streak 4y ago
      That's interesting. Good to know.
  • hither_shores 4y ago
    > Again, I'm on the outside looking in, I don't work in the field so I'm not 100% sure if this is accurate It's not. Point by point: > I've always heard that string theory was an untestable theory True in a certain light, but misleading. Any theory of quantum gravity is going to be untestable with current methods: the relevant energy scales are just too high. That doesn't mean they won't ever be testable. We might figure out a qualitatively better collider design, or find a way to get useful data from astronomical observations, or find some other clever way around the problem. Or we might not. Theorists would love to have more experimental evidence to work with - but wanting doesn't make it so. A somewhat more legitimate concern is the size of the "string landscape": (perturbative) string theory permits many, many, many different possible values for different physical constants. It's likely, but not certain, that this is also true nonperturbatively. If so, then we can't use the measured values of those constants as evidence for or against string theory. This is unfortunate, but hardly unique: the standard model, after all, permits infinitely many such possibilities. > and research on it soaked up a large amount of academic budgets and grant money Not really. Most physics funding goes to applied research, most pure research funding is for experimental work, and the majority of theory funding is not for high energy theory. I don't know whether most high energy theory grants go to string theorists: it's possible. > And was ultimately fruitless Only insofar as all work on quantum gravity has been "fruitless".
• isolli 4y ago
  Only 30 years ago we had never seen a brown dwarf, even though its existence had been theorized much earlier. There are not enough brown dwarfs to account for the missing mass in the universe, but is it at all possible that some other type of body that we have not yet seen could account for it? Or is the requirement that dark matter be non-baryonic a fundamental requirement of the theory?
  • sethrin 4y ago
    IANAP. AFAIK, Large massive bodies (MACHOS) have been ruled out by observation, and baryons would be detectable through EM.
• qikInNdOutReply 4y ago
  I have a hard time imagine the shape of dark-matter. What does that look like, a particle iceberg squeezed into a hidden dimension that surrounds all things? Like a Neutrino that does not travell, but instead waves like seaweed? How does it look in 3dimensional terms?
• NoriakiNamba 4y ago
  All the celestial bodies that make up the system are in free fall (acceleration) toward the center of the system. Gravity is the action that tries to maintain a defined acceleration towards the gravity source according to the distance from the gravity source. Therefore, if the gravity source accelerates, the gravitational action should be considered different from when the gravity source is stationary. Sciama named this action "inertial induction" and proposed it. All the stars that make up the galaxy are in free fall (acceleration) toward the center of the galaxy. Current calculation methods do not take this fact into account at all. There is no way that the observation can be explained by a calculation method that ignores the facts. I have written a paper* on how the inertial induction of stars works in galaxies. *N. Namba, "Stellar movement in the galaxy explained by inertial induction", Phys. Essays 15, 156(2002) In addition, I mentioned the essence of gravity and inertia in a 2014 paper, showing that the existing theory of gravity is incomplete. The full text of this paper is now available on GALE ACADEMIC ONE FILE. Please see attached. https://go.gale.com/ps/i.do?p=AONE&u=googlescholar&id=GALE|A444208025&v=2.1&it=r&sid=googleScholar&asid=a5ea3528 https://go.gale.com/ps/i.do?p=AONE&u=googlescholar&id=GALE|A...
• joshspankit 4y ago
  I landed on the page and there doesn’t seem to be an article or a “pay/register to view” prompt. Just the title, the hero image, a word count, and some comments (which prompts to register to add comments) Does it load for others?
• willmadden 4y ago
  Hallelujah. Whenever scientists invent things we cannot measure to explain why their theories are still valid, you know you have a problem. The three biggest issues with the sciences today are: 1) grant money purse strings controlled by bureaucrats with a political agenda 2) the "peer review process" and lack of open source, real-time, collaborative research 3) scientists who become dogmatic about their field of expertise, even if all of their work is built on a flawed theory All three are interrelated and a cancer in terms of humanity's progress. I'm sure you'll find plenty of examples of #3 in this thread, too.