HST and 'dark matter' |
HST and 'dark matter' |
Guest_PhilCo126_* |
May 11 2007, 05:13 PM
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Guests |
ASA Updates Plans for Hubble 'Ring Of Dark Matter' Briefing
GREENBELT, Md. - NASA will hold a media teleconference at 1 p.m. EDT on May 15 to discuss the strongest evidence to date that dark matter exists. This evidence was found in a ghostly ring of dark matter in the cluster CL0024+17, discovered using NASA's Hubble Space Telescope. The ring is the first detection of dark matter with a unique structure different from the distribution of both the galaxies and the hot gas in the cluster. The discovery will be featured in the June 20 issue of the Astrophysical Journal. |
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Jul 13 2010, 08:04 PM
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#2
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Senior Member Group: Members Posts: 1018 Joined: 29-November 05 From: Seattle, WA, USA Member No.: 590 |
Which means the maximum entropy ought to be when all the particles clump together into a single mass and that mass cools to the background temperature of the universe. (Assuming no black hole.) If there's angular momentum, I think the system can get trapped in a local minimum, where there are multiple bodies orbiting one another; entropy would be lower if they could collide, coalesce, and cool down, but there's no mechanism for them to do so.
Back to the paper, I read through it more carefully, and what he seems to be saying is that if we assume that entropy somehow (means unspecified) increases when one mass approaches another, then, given certain choice of parameters, he can derive the usual laws of gravity. He gives no clue what entropy actually means in this case. Far as I can tell, anyway. --Greg |
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