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Thread: What Could the Matter of Dark Matter Be?

  1. #1 What Could the Matter of Dark Matter Be? 
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    I found it odd that dark matter while considered matter has not been considered an element.
    Hypothetically, if dark matter were an element it would have to be one of a huge atomic mass. Running with this hypothetical, Could there be an element that is so heavy that the atomic orbits no longer possess the capability to allow light to bounce off of it? As in, it absorbs all light instead of slivers like in a typical elemental spectrum.

    Going further, if that is the case could black holes force more common elements into this larger “lightless” element from the sheer gravity involved in a black hole? Black holes might be responsible for dark matter, perhaps even dark matter themselves. Remember, galaxies do contain massive black holes in the center and scientist have yet to find physical proof of what holds galaxies together. Clearly, supermassive black holes and dark matter play a huge role in the formation of galaxies. Maybe they are connected some how or even one in the same. Could anyone debate with me on this concept or give some professional reasoning that I might have overlooked?
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    An interesting idea. It is possible for an atom to absorb light and then convert that energy into kinetic energy, but seemingly this would have a limit. If the atom ran into something else, it would then transfer that energy. So perhaps we should see the results of such impacts. We'd have to work out the rate of absorption required to account for the mass, then figure out what that would to to the energy content of a galaxy or galaxy cluster and the luminosity. (Reminds me of some attempts to link absorption of dust to dimming and reddening of galaxies/supernovae in order to confound redshift vs. distance calculations.)

    Another problem would be looking at the relative abundance of the decay produces of such an element. What is the half-life of such an element? We would then have to work out production and destruction rates for various stars/galaxies and then look to the change in density of this element over cosmological time. If there turns out to be a difference in the ratio of luminous matter to dark matter over time, then this could be a viable solution or part of the solution.

    A really big problem is that this dark matter solution makes dark matter into baryonic matter (essentially normal matter) and thus increases the presence of baryonic matter in the very early universe. I suspect that dark matter made up of heavy elements would be very difficult to form in the early universe. Additionally a large density of baryonic matter in the early universe probably violate two things. 1) They stop the universe from forming the relative abundance of light elements that seems to be there. 2) They might not allow for the observed spectrum of inhomogeneities in the early universe that form the basis for contemporary research in cosmology.
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    I failed to consider the early universe. One would think such elements wouldn't be required in the beginning as the universe was a hot soupy mess void of collective structures such as galaxies. Still, there is the issue of there then having to be 5x more matter than previously calculated, even if it is all just hydrogen/helium. I do know that there is a scientific consensus on the amount of matter in the universe, is it possible we could be mistaken? Science is after all, about taking no idea, not even our own, at face value.
    Eh I'm grasping now, I don't like it.

    I'll have to think this over. The dark matter theory always seemed off, as if it made more sense mathematically than physically. This becomes more troubling when even the quantum realm seems more realistic at times. There just must be more to dark matter than we currently know. What creates it for one thing. Also black holes strange matter shrinking ability seemed bizarre too. Is an iron atom still an iron atom in a black hole? If so how does it shrink yet maintain its elemental form. Atom orbital electrons, as far as I'm aware, do not share the same orbits together.
    Oh the things that keep me up at night,
    Thank you for your quick reply PhysBang
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    (Sorry, quote button doesn't work for me on this site).

    Dark matter is "dark" because we can't see it. The "light absorbing" quality in the OP would make actual dark areas of the sky, that we'd be able to see. (By them blocking out or at least dimming/blurring what's behind).

    Dark matter - Wikipedia, the free encyclopedia
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    The quote button does not work for me on this forum either. As far as I know, neither dark matter or energy have been directly detected, and that is why they are called "dark" - granted maybe not the best term for something that is thought to exist because of otherwise not currently explainable seemingly continued expansions of space that seem to defy pull gravity.

    I think a lot of this is based on red shift phenomenon seen from space telescopes that do not really fit into current scientific understandings and theories.
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  6. #6  
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    Pzkpfw

    Your right I finally found some information about how dark matter does not seem to emit or absorb light, though its affects can be seen by the light around it since it bends around strong gravitational influences. HubbleSite - NewsCenter - Hubble Finds Ring of Dark Matter (05/15/2007) - The Full Story

    I do apologize I must of been google searching half asleep when I was looking up this info I missed some big parts.
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  7. #7  
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    Quote Originally Posted by Alklazaris
    I found it odd that dark matter while considered matter has not been considered an element.
    What ever gave you that idea? Elements are made of protons, neutrons and electrons. Neutrons and protons are baryons. Baryons have been eliminated as being dark matter. See
    Dark matter - Wikipedia, the free encyclopedia
    There are three separate lines of evidence that the majority of dark matter is not made of baryons (ordinary matter including protons and neutrons):

    * The theory of Big Bang nucleosynthesis, which very accurately predicts the observed abundance of the chemical elements,[12] predicts that baryonic matter accounts for around 4–5 percent of the critical density of the Universe. In contrast, evidence from large-scale structure and other observations indicates that the total matter density is about 30% of the critical density.

    * Large astronomical searches for gravitational microlensing, including the MACHO, EROS and OGLE projects, have shown that only a small fraction of the dark matter in the Milky Way can be hiding in dark compact objects; the excluded range covers objects above half the Earth's mass up to 30 solar masses, excluding nearly all the plausible candidates.

    * Detailed analysis of the small irregularities (anisotropies) in the cosmic microwave background observed by WMAP and Planck shows that around five-sixths of the total matter is in a form which does not interact significantly with ordinary matter or photons.
    That's only part of it. You need to reads the whole thing because some baryonic matter are candidates for dark matter. i.e. A small proportion of dark matter may be baryonic dark matter: astronomical bodies, such as massive compact halo objects, that are composed of ordinary matter but which emit little or no electromagnetic radiation.

    Hypothetically, if dark matter were an element it would have to be one of a huge atomic mass. Running with this hypothetical, Could there be an element that is so heavy that the atomic orbits no longer possess the capability to allow light to bounce off of it? As in, it absorbs all light instead of slivers like in a typical elemental spectrum.

    Quote Originally Posted by Alklazaris
    Going further, if that is the case could black holes force more common elements into this larger “lightless” element from the sheer gravity involved in a black hole? Black holes might be responsible for dark matter, perhaps even dark matter themselves.
    Black holes are on the list of objects which could compose part of the dark matter we detect. Dark matter need not be of only one kind of matter by the way.
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    Quote Originally Posted by pzkpfw View Post
    (Sorry, quote button doesn't work for me on this site).
    Yes, there seems to be a bug of some sort. A workaround is to click twice on the quote button. That seems to work most of the time.
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    Quote Originally Posted by mayflow View Post
    The quote button does not work for me on this forum either. As far as I know, neither dark matter or energy have been directly detected, and that is why they are called "dark" - granted maybe not the best term for something that is thought to exist because of otherwise not currently explainable seemingly continued expansions of space that seem to defy pull gravity.

    I think a lot of this is based on red shift phenomenon seen from space telescopes that do not really fit into current scientific understandings and theories.
    Please google the terms "dark matter" and "dark energy". You don't have to just guess and make up stuff. It makes for far higher-quality discussion if one makes at least a basic effort to learn a bit before posting "information."

    In this case, the evidence for dark matter comes primarily from galaxy rotation curves. It has zero to do with redshift. Nothing. Zip. Nada. See, e.g., Galaxy rotation curve - Wikipedia, the free encyclopedia. From the plots, you can see the discrepancy between what is predicted on the basis of visible matter, and what is actually observed.

    The evidence for dark energy comes from the observation that the universe's expansion is accelerating (see, e.g., Dark energy - Wikipedia, the free encyclopedia). That, in turn, comes primarily from observations of type 1a supernovae (which are excellent "standard candles" whose intrinsic luminosity is well known, so that observed brightness can be reliably correlated with distance). Other measurements fit as well.
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  10. #10  
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    Quote Originally Posted by Alklazaris View Post
    I found it odd that dark matter while considered matter has not been considered an element.
    Hypothetically, if dark matter were an element it would have to be one of a huge atomic mass.
    It's not as odd as one might think. For one, dark matter appears not to interact electromagnetically at all. An element, even (actually, especially) a high-Z one, possesses electrons that would offer ample opportunity for electromagnetic interaction. As atoms grow more massive, their ionisation potentials actually decrease. The observed non-observation of dark matter tells us that something more exotic than ordinary matter is involved. On top of that, there is the additional difficulty of the instability of massive atoms. Although there are periodic "islands of stability" among the transuranics, "stability" is a relative term here. We would see plenty of radiation from the decay of these putative high-Z atoms. In short: invoking high-Z elements as a major constituent of dark matter doesn't work.
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