Comments by "EebstertheGreat" (@EebstertheGreat) on "The Absurd Search For Dark Matter" video.

Discovering dark matter in this experiment won't necessarily lend any credence to string theory. There are plenty of much simpler extensions to the standard model that predict the existence of WIMPs. It is likely that we will never directly confirm any of string theory's predictions, even if it is true. Most versions are still generally considered untestable in practice.
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@aqualung2000 It's not like in the past 40 years, we have found evidence that every last particle had been discovered. Dark matter seems like a more robust hypothesis than ever. But of course alternatives are being explored. There are papers published on MONDY and other alternatives every day. But in spite of this, dark matter still explains observations better than anything else we have come up with. Also, 40 years is not a long time. It took nearly 50 years to find the Higgs boson after it was theorized, and that's in spite of the fact that we knew exactly what to look for. And we will probably never detect a graviton. There is no expectation that we should have found dark matter by now, except in a few very optimistic models.
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@harrison00xXx The density of radiation (which is mostly light) is well-constrained by our models of cosmology. But more importantly, we can see light. The whole thing about dark matter is that it's dark; there appears to be mass where we don't see anything. Light does produce a pressure, and a photon gas also has mass and thus gravitationally attracts matter. We can measure these directly, and they do not explain the enormous discrepancy between the mass of observed matter in galaxies and the mass calculated from rotation curves.
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@harrison00xXx The supermassive black hole Sgr A* has a mass of only about 4 million solar masses. By comparison, the Milky Way has a mass of about a trillion solar masses. So the black hole has only 0.0004% of the galaxy's mass. Most stars are not orbiting the black hole so much as the core of the galaxy, or in a sense, really the entire galaxy. Vacuum energy is a conventional but problematic explanation for dark energy, not dark matter. A positive vacuum energy would actually produce an effectively antigravitational effect and cause the universe to expand. However, theoretical computations suggest vacuum energies dozens of orders of magnitude higher than the observed cosmological constant, so we don't really know what's going on.
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@harrison00xXx We do not live in a black hole.
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@GeorgeMonet Well, all stable massive particles that we know about interact with the weak force at least. They don't necessarily interact electromagnetically, because they don't all have an electric charge. For instance, neutrinos have no charge, which is part of what makes them so hard to detect. Neutrinos qualify as WIMPs, though there are not enough known neutrinos to account for all the mass of dark matter. No matter what dark matter is made of, it certainly does interact with light gravitationally (if "interact" is even the right word). Gravitational lensing from dark matter is observable. Unfortunately, that kind of observation gives us practically no information about dark matter except for the total mass of it in some place. However, dark matter does not absorb or emit light (at least to any appreciable degree), which is what makes it dark.
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