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Thread: has dark matter been proven?

  1. #1 has dark matter been proven? 
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    I remember hearing several years ago that the existence of dark matter wasn't quite known, that scientists weren't yet comfortable talking about it as though it had been proven conclusively. Now-a-days, whenever I hear reputable sources talking about the subject, it's talked about as though it has finally become an established fact.

    My question: does the scientific community generally regard the existence of dark matter "proven"? If so, was this shift recent? What are some of the examples of evidence that recently came in (or have been in for a while) that encouraged scientist to take the attitude of certainty about dark matter's existence?


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    In a sense, no. In, a sense, yes.

    There is no known particle that is dark matter. All the properties of dark matter haven't been figured out yet. In part, this is because figuring out galactic dynamics is something that needs a lot of work.

    However, there are many, many co-reinforcing observations out there that only make sense with dark matter. Even people working on alternative cosmologies, like Jayant Narlikar, have been forced to adopt dark matter in order to get their hypotheses to fit the available observations.


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  4. #3  
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    there does seem to be something that is otherwise unaccounted for...so the term dark matter is used....it seems to exert a gravitational force,that ordinary matter does not account for.approx equal to 4 times gravity maybe 5...
    so far this dark matter is indetectable.
    the maths shows it is there,based on observation of its effects.
    .
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    Quote Originally Posted by PhysBang View Post
    However, there are many, many co-reinforcing observations out there that only make sense with dark matter.
    - And there is some, some theory out there that DOES make sense of all these co-reinforcing observations WITHOUT dark matter.
    Name: Anisotropic Geometrodynamics.
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    In astronomy and cosmology, dark matter is a type of matter hypothesized to account for a large part of the totel mass in the universe. Dark matter cannot be seen directly with telescopes, evidently it neither emits nor absorbs light or other electromagnetic radiation at any significant level. Istead, its existence and properties are inferred from its gravitational effects on visible matter, radiation, and the large scale structure of the universe. Dark matter is estimated to constitute 84% of the matter in the universe.

    The Standard Model fells short of being a complete theory of fundamental interactions because it does not incorporate the physics of dark energy or either the full theory of gravitation as described by general relativity. The theory does not contain any viable dark matter particle that possesses all of the required properties deduced from observational cosmolagy. It also does not correctly account for neutrino oscillations (and their non-zero masses). Although the Standard Model is believed to be theoretically self-consistent, it has several apparently unnatural properties giving rise to puzzles like the strong CP problem and the hierarchy problem.
    Everything has its beauty, but not everyone sees it. - confucius
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    Hello and greetings, I would like to begin my post with the following disclaimer, my realm of scientific expertise does not include quantum physics, aside from my armchair reading. With that notion, I must state I find 21st century physic "quests" about as intriguing as it gets, for lack of a better stated sentiment. My question is this: with regard that physics generally excepted the notion of ether, basically as a community, how does the physics community not fear that some of modern day principles are not a repeat of history? I must add I am not looking to begin any pot stirring, as it were. I would like for a kind soul to educate me. Further, I am not looking to inspire any doubt to add credibility to philosophical/political banter. I find that tiresome. Just want to hear a little bit of the science, not on a theoretical physicist scale but also not on a lay person scale either.
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    And here is another approach which can explain the observed phenomena without dark matter and dark energy :

    Scalar
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  9. #8  
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    Quote Originally Posted by Roberto View Post
    Quote Originally Posted by PhysBang View Post
    However, there are many, many co-reinforcing observations out there that only make sense with dark matter.
    - And there is some, some theory out there that DOES make sense of all these co-reinforcing observations WITHOUT dark matter.
    Name: Anisotropic Geometrodynamics.
    http://arxiv.org/ftp/arxiv/papers/0809/0809.1817.pdf

    Quote Originally Posted by Markus Hanke View Post
    And here is another approach which can explain the observed phenomena without dark matter and dark energy :

    Scalar
    Any ideas on how to account for the Fifth Force?
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    Quote Originally Posted by Neverfly View Post
    Any ideas on how to account for the Fifth Force?
    What fifth force ?
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    Quote Originally Posted by Markus Hanke View Post
    What fifth force ?
    Read your link.
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  12. #11  
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    A theory that postulates that we can't detect 84% of the matter in the universe raises more questions than it answers. That is like saying we know all about the ocean except for the water.
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    Quote Originally Posted by Neverfly View Post
    Quote Originally Posted by Markus Hanke View Post
    What fifth force ?
    Read your link.
    I meant what model of that force are you referring to ? There are several distinct approaches, most of which however involve scalar fields.
    In STVG this is a vector field, but one that depends only on the energy of the object ( as in GR ), just like gravity does, but crucially it would have to be carried by spin-1 bosons, which may or may not be massless ( big question - how would a spin-1 boson couple to a rank-2 tensor field ?! ).

    To answer your question - we would probably be looking for a new particle, but one that would be extremely hard to detect at small scales, analogous to the graviton. At large scales its effects would however be rather obvious, and it would seem that is what we indeed observe.
    I know, it's all a bit dodgy, but I think it is a hypothesis which is worth some further consideration, because it does eliminate the need for dark matter altogether.
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  14. #13  
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    Some slight chopping:

    Quote Originally Posted by Markus Hanke View Post
    but I think it is a hypothesis which is worth some further consideration, because it does eliminate the need for dark matter altogether.
    Agreed on that!
    Quote Originally Posted by Markus Hanke View Post
    I meant what model of that force are you referring to ? There are several distinct approaches, most of which however involve scalar fields.
    Actually, I think that was my question to you... <scratches head> If I knew what model you had in mind, I wouldn't need to ask how you account for it.
    ETA: I mean, answer as if I'm actually dumb. Because I actually am.
    Quote Originally Posted by Markus Hanke View Post
    In STVG this is a vector field, but one that depends only on the energy of the object ( as in GR ), just like gravity does, but crucially it would have to be carried by spin-1 bosons, which may or may not be massless. To answer your question - we would probably be looking for a new particle, but one that would be extremely hard to detect at small scales, analogous to the graviton.
    A graviton, if I'm not mistaken, is extremely hard to detect. Makes a neutrino look like a New Yorker. I think it was wikipedia, I'm not sure, where I read it, said that a Jupiter sized detector near a neutron star would still probably not detect a graviton.
    That'll just ruin your whole day...
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    Quote Originally Posted by Neverfly View Post
    Actually, I think that was my question to you... <scratches head> If I knew what model you had in mind, I wouldn't need to ask how you account for it.
    ETA: I mean, answer as if I'm actually dumb. Because I actually am.
    Sorry about that...I think we were talking past each other here
    What I have in mind would be a new particle, a spin-1 boson which is either massless, or at least not very massive.

    A graviton, if I'm not mistaken, is extremely hard to detect. Makes a neutrino look like a New Yorker. I think it was wikipedia, I'm not sure, where I read it, said that a Jupiter sized detector near a neutron star would still probably not detect a graviton.
    That'll just ruin your whole day...
    Absolutely correct. It would be analogous with the vector field in STVG - it would be really difficult to detect experimentally.
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    Can someone answer this:

    Does dark matter get affected by the matter it attracts? Or is it "magically mired" in space? Basically, does dark matter move towards shit?
    It is by will alone I set my mind in motion.
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    Quote Originally Posted by pyoko View Post
    Can someone answer this:

    Does dark matter get affected by the matter it attracts? Or is it "magically mired" in space? Basically, does dark matter move towards shit?
    If dark matter has an observable gravitational effect on other bodies/light, then it is reasonable to assume that those bodies in turn have an effect on dark matter. That is just how gravity works.
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    And I am guessing dark matter attracts dark matter? So that it clumps together like matter?
    It is by will alone I set my mind in motion.
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    Quote Originally Posted by pyoko View Post
    And I am guessing dark matter attracts dark matter? So that it clumps together like matter?
    I would presume dark matter behaves like any other matter, at least in the domain of gravitation. Whether it clumps together or not depends on whether it is best described as a solid, a liquid or a gas.
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    Quote Originally Posted by Markus Hanke View Post
    Sorry about that...I think we were talking past each other here
    Nah, I scrolled up and read, instead of skimming- It was that I let some things go over my head and didn't put it together. It's on me, not you.

    Quote Originally Posted by Markus Hanke View Post
    What I have in mind would be a new particle, a spin-1 boson which is either massless, or at least not very massive.
    This is the bit I had seen you say but for reasons I cannot explain... It didn't sink in that when you said that, you meant to say what you said. I think I treated it as you were giving an example, rather than an answer.
    Remember the dumb I mentioned above? It applies here. I blame heavy lack of sleep.
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  21. #20  
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    Quote Originally Posted by Markus Hanke View Post
    Quote Originally Posted by pyoko View Post
    And I am guessing dark matter attracts dark matter? So that it clumps together like matter?
    I would presume dark matter behaves like any other matter, at least in the domain of gravitation. Whether it clumps together or not depends on whether it is best described as a solid, a liquid or a gas.
    I wonder if enough dark matter can form a dark matter black hole :P What if dark matter is not homogenous and also forms dark matter elements :P Also does dark matter create space-time distortion like matter, or only gravitates matter? Also maybe "cat" spelt backwards is "dog".
    It is by will alone I set my mind in motion.
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    Actually, this question is related to the question: what is our world composed of?. Technically, we have enough experiment results to explain the dark material or dark energy. But the current physics's interpretation is not in a right way.
    Let start with electron, we always think electron is a small particle. But we ignore the electric field around it. The pair production experiment tells us that the photon and electron and positron can be exchanged. This means the electron is made up by electromagnetic field. So the electric field around electron is the extension of electron. A whole electron is a very large particle because the electric field can extend very far away. Other experiment proves that our world is made up by electric field. Based on different structure, some electric field is called particle, some is called field and some is called energy. We can detect the particle, but not the field. That is why we called it dark.
    If you are interested to read my opinion, please email me. I can send a book to you.
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  24. #23  
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    Quote Originally Posted by pyoko View Post
    I wonder if enough dark matter can form a dark matter black hole
    A black hole as a system has really only three degrees of freedom - mass, angular momentum, and electric charge. Therefore, a black hole formed by the accumulation and gravitational collapse of dark matter would look exactly the same as any other black hole.
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