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Message: <blockquote data-quote="Balesir" data-source="post: 6159961" data-attributes="member: 27160">No; black holes are localised (almost point phenomena, in a galactic context), so you can see how their gravitational effect changes with distance from them. The galactic rotation anomaly is partly that the velocity changes too little as you get further from the galactic centre.Black holes were considered, exoplanets and brown dwarves were considered - all manner of "mundane" explanations. The bottom line is that none of them work, however. The "missing mass" discrepancy is not small - ~75% on the basis of the rotation anomaly alone (and other anomalies thought to be related, such as anomalous "galactic lensing" - the way light is deflected by the gravity well around far away galaxies - have also been found). I.e., at least four times (and currently thought to be maybe seven times) as much mass is needed in the universe as we can see. It's rather a big discrepancy.What we call "reflection" is actually the absorbtion of light (electromagnetic) energy by the electrons in matter, causing those electrons to become "excited" until the drop back down to their "ground state", re-releasing the photon that excited them in a different direction. Metals and non-metals do this in different ways because metals have "free" electrons while non-metals don't, so metals can reflect a coherent picture while (most) non-metals don't.Well, no, neutronium (which I had to look up) is a special case and very speculative. Neutrons don't have charge, but they do have a slight electronic dipole, and they interact with atomic nuclei through the strong nuclear force, since they are hadrons - which was a class that I forgot to say Dark Matter doesn't belong to.Basically, particles of matter interact via one of the "four fundamental forces" - electromagnetism, the strong and weak nuclear forces and gravity. Dark matter - if it exists - interacts only through the last one, gravity.Without being either atoms (i.e. hadron-based matter) it's impossible for anything to be what we would call "dust". Certain other forms of matter are supposed to exist in the extreme conditions within neutron stars and the like, but you'd hardly call those "dust" - they pretty much have to be a big "lump".Without electromagnetic interactivity, light is neither absorbed nor reflected (which are actually similar - what we call "absorbtion" is generally absorbtion and re-emission at a different wavelength, often IR, whereas "reflection" is absorbtion and re-emission at (approximately) the same wavelength).Right - it either travels straight on by without interacting, or it gets absorbed and then re-emitted sooner or later. With "Dark Matter" the idea is that it simply doesn't interact.True, although an astounding number of people seem to want to try to apply real world physics to fantasy worlds. Go figure.Oh, yeah, here you're right. The list of issues with trying to do this just goes on and on, but I have pretty much always found that trying to mix science with D&D ends badly, no matter how you cut it!</blockquote>

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