Simulation Predicts Clumps of Dark Matter Within Galaxies

A team of researchers has simulated the gravitational interaction of dark matter particles over the course of a hypothetical 13.7 billion years. They found that the particles tended to form clumps large enough to assist in the formation of galaxies. The results contradicted observations from previous, smaller studies, but they lent support to an unrelated simulation of how the Milky Way formed. UCSC's press release is also available. Quoting ScienceNews: "The clumps of dark matter in the simulation have densities that are remarkably similar to densities that a University of California, Irvine research group found when simulating the formation of the Milky Way and its satellite dwarf galaxies, says James Bullock, the astrophysicist who leads the UC-Irvine group and was not involved in the new study. 'This is a remarkable success of the particular model simulated and adds strong support to the idea that the dark matter is made up of particles that are "cold." There are a number of planned experiments aimed at detecting the dark matter that are betting on it being cold, so this is generally good news for the community,' Bullock says. And, [study co-author Piero Madau] notes, larger simulations that might help constrain the nature of dark matter even more are already in the works."

Where's the evidence?

[Nazlfrag]

I doubt this simulation did more than let them see what they wanted to see. "The researchers note that the simulation does not model any forms of normal matter such as stars or planets." Hardly a complete picture they drew.

Why the obsession dark matter? Say with MOND, why are we so scared to think that perhaps Newtonian mechanics aren't quite enough to calculate with on galactic scales? Why do they think MOND is for cranks and crackpots? What of a static non-expanding universe and alternate redshift paradigms? Are they not just as feasible as exotic matter that only interacts gravitationally?

That's a lot of questions, so I'll break it down to one. I'm just curious as to why dark matter is so widely supported, is it merely because breaking the standard model makes physicists too uncomfortable?

Slightly off topic: Dyson Spheres

[Abeydoun]

I've been curious... if there was an incredibly advanced civilization that was capable of building near perfect dyson spheres [wikipedia.org] around large expanses of space absorbing essentially all the radiation of the stars within it, wouldn't that look like "dark matter"?

Cosmic Smog?

[Tablizer]

It would certainly be interesting if dark matter turned out to be some kind of pollution from advanced civilizations.
     

Gravity from "elsewhere"?

[YttriumOxide]

For some time, I've been making random notes from articles relating to dark matter, string theory and quantum entanglement. I've been trying to form a hypothesis of dark matter with information from all of these three.

Interestingly, this article has now given a lot more focus to one part of the idea that was forming that was a bit "wishy-washy" before (okay, it's still very wishy-washy, but less so now).

The overall concept is basically along the lines of quantum entanglement being a property of the fact that two entangled particles are in fact just ONE string that's being bent through space in some rather unconventional ways (extra dimensions neither being "large and flat" nor "very very small and coiled", but rather "hideously complex monstrous things").
This, combined with gravity ("graviton"strings) being freely able to travel through those dimensions rather than tied to an endpoint (hence appearing much weaker than the other forces, even though ALL forces have absolutely identical strength (another wild-ass guess, just because it would be "nice")) would lead us to an elegant idea about dark matter actually being gravity from perfectly normal matter that happens to be showing up in unexpected places.

The fact that there are clumps of it definitely does not blow my ideas out of the water, but it does mean I need to re-work my idea of "hideously complex monstrous things" for the extra dimensions as I was assuming dark matter showed up "generally" in areas with other matter rather than specific clumps as "normal" does. It needs to be more structured than I had been thinking for a clump of matter in one place to form a "clump of dark matter" (e.g. the gravitational effect seen) elsewhere. That's actually a good thing though, because any structure lent to the process makes it closer to a testable hypothesis (anything completely unstructured could never become one, and having "no real clue" about the structure as I was, made it far too vague.)

Note that this is still a very early infancy idea, and is somewhat around the "wild guess" point rather than even "hypothesis", so I'd be quite happy for people to comment on this - can anyone blow me completely out of the water on this line of thinking? Or can anyone offer ideas that support it? Or even just expand it a little? Does anyone know of any other research along these lines that I could read?

Re:Where's the evidence? (emission, too!)

[pterandon]

I think gravity is safe. Speaking as a layman, do we really know THAT much about the emissivity of the ordinary matter around us-- on galactic scales? I cannot help but think our theories of the emissivity of objects is not so robust that we have to come up with a new class of matter when this decade's calculations of gravity vs. emission don't add up. Seems like the simpler solution is to refit the emission theories. Q: And aren't there a whole bunch of reasons why emitted photons won't reach terrestrial eyeballs? What if there were really big objects out there? Wouldn't the centers be practically invisible to us?

Re:Gravity from "elsewhere"?

[YttriumOxide]

On large scales, physics is pretty classical

Other than the large amount of seemingly "dark matter"...

entanglement just isn't that relevant on cosmological scales

Certainly true, but I wasn't really implying it needs to be. If we have a pair of entangled particles, they can THEN be separated by (apparently) quite any distance in classical space and nevertheless remain entangled. We haven't found a good way to use this as "faster than light communication", and there are very strong arguments that it can't be, however it seems to remain fact that these particles are somehow "connected" despite being physically quite separate ("spooky action at a distance"). This is why my hypothesis considers that they may actually not be physically separate at all - they are "right beside each other" through twisted "extra" dimensions, just in some way that we currently do not have the ability to measure or understand particularly well. This leads on to the idea of "dark matter" being gravity from "nearby" objects that are classically quite distant, but in reality quite "close".

Note, I don't actually disagree with you, but clearly there's something going on that we really don't understand very well yet.
Also note that I'm probably wrong - my idea is just that, an idea - I don't necessarily believe it!