Vast Web of Dark Matter Mapped 86
astroengine writes "Astronomers from the University of British Columbia and University of Edinburgh have created a vast cosmic map revealing an intricate web of dark matter and galaxies spanning a distance of one billion light-years. This is the largest map of its kind and demonstrates that this large-scale web stretches across the universe in all directions. The results of this groundbreaking discovery were presented at the American Astronomical Society conference in Austin, Texas on Monday."
What are the odds... (Score:4, Interesting)
...dark matter eventually turns out to be like luminiferous aether from the 19th century? I don't believe anyone has directly observed dark matter.
Re:What are the odds... (Score:4, Interesting)
From the way it clumps around galaxies and clusters of galaxies, I think we know that it isn't moving at or close to the speed of light, which rules out gravitons and a bunch of other things.
Re:What are the odds... (Score:2, Interesting)
So was Dark Matter. People felt that the Aether should exist because the existing theories at the time governing the physical laws of the universe predicted that it ought to exist. and its nonexistence would mean that those theories were wrong (and they were). What is particularly interesting about proving the non-existance of the Aether (who says you can't prove that something doesn't exist?) is that it was accomplished without adequately forming another explanation for what was expected to happen... it was simply a blanket disproof that stated that those expectations (in particular, that the wave properties of light would not be possible unless the phenomenon were happening inside of some medium) were simply wrong, with no real explanation as to why. With Dark Matter, if it is disproven, I expect it is much more likely that we will actually discover how our existing theories are wrong at roughly the same time that the existence of Dark Matter is disproven.
Re:What are the odds... (Score:2, Interesting)
One of the many things that has always bothered me about Dark Matter is how it has gravity but at the same time doesn't seem to be affected by gravity.
Case in point, an Astronomer was able to map out the DM field around a pair of colliding galaxies but the DM cloud from one galaxy had just sailed through the DM cloud of the other galaxy without any apparent affect. But at the same time all the visible matter behaved exactly as predicted, swirling together and merging into a larger galaxy.
Does anyone know why these big clouds of Dark Matter, each with enough gravity to hold a galaxy together, don't collapse in on themselves. Regular matter gets blown around by light, a cloud of Hydrogen collapses and heats up too fast the heat blows the cloud apart, preventing further collapse. So what keeps DM from collapsing into some kind of super sized uber black hole?
Re:Did I miss... (Score:4, Interesting)
There's a bit more too it than that though, dark matter is no longer just a guess, there is more direct evidence to back it up. To extend your analogy, lets say instead of a single ball hanging you have hundreds of them. A follower of the string theory (pun definitely intended) might make a prediction: some of the balls should have a detectable periodic motion from past disturbances. A thorough survey of the floating balls shows that yes, some of them are swinging like pendulums. It doesn't prove that the balls are hanging from strings, but it means that there's yet another effect that a modified theory of gravity has to take into account, which can be explained very easily by positing the strings. Similarly, there have been a host of indirect observations which show that either there is large amounts of matter that we can't detect or there are dozens and dozens of gravitation effects that are not only not included in current theory but in some cases appear to be mutually exclusive.
Re:What are the odds... (Score:2, Interesting)
Lack of friction and no way to dissipate energy or angular momentum. It cannot radiate photons, as doing so would make it not dark.