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blondgecko
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Aug 23, 2006, 3:52 AM
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Registered: Jul 2, 2004
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Strong evidence for dark matter found (WARNING: Educational)
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Link. This is pretty cool, if you're interested in this sort of thing. Observations of a pair of galaxy clusters that collided "recently" show that their centres of gravity are not where they should be according to the distribution of visible matter. Basically, dark matter is posited to only interact with itself and with "normal" matter via gravity. So, when these clusters collided, the dark matter passed straight through essentially unhindered, while the super-hot interstellar gas crashed together and slowed down. This effectively shifted the centre of gravity away from the centre of mass of the visible matter, something which can be observed by looking at gravitational lensing of more distant galaxies behind the region of interest. Pretty strong evidence that the stuff actually exists, and against the opposing theory that gravity just acts differently over longer distances. Of course, doesn't tell us anything about what it actually is...
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tradman
Aug 23, 2006, 10:31 AM
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Registered: Jan 14, 2003
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Wow. That's pretty incredible. Hopefully this can lead to more observations that might give us a better idea of what it is and whether it's useful. Wonder what the variable gravity crowd will make of this?
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epoch
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Aug 23, 2006, 10:58 AM
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Registered: Apr 28, 2005
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It's too early to absorb this. Interesting read. Does this mean that my moon boots won't work anymore?
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overlord
Aug 23, 2006, 2:56 PM
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Registered: Mar 25, 2002
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i read about it yesterday, but kinda decided against posting here. very interesting though. what is the most striking feature about it is the fact that they have no idea about what kind of a universe we live in... will it collapse unto itself, will it continue to expand indefinitelly, or is it that special, really rare type of universe that will, in the end, stabilize itself.
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