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Post by dopeydog on Sept 7, 2008 12:13:21 GMT
"orbits the center of mass of this Universe"
Didn't know the universe rotated around a center. Source?
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Post by stranger on Sept 8, 2008 1:11:59 GMT
A source for the center of mass of the Universe?
After sixty years titles escape me, so I would not try to remember the name of that astronomical tome. It was in blue covers, ran around 1200 pages and smelled like dust. And I was probably the first person to open it after the librarian put a number on its spine.
But consider: Everything in this solar system rotates around the center of mass of the system. So much so the that Sun wobbles a bit and the CM is frequently outside the photosphere.
It is much the same with our Galaxy. Which supposedly at least rotates around a center of mass colocated in a humongous black hole with a few tens of millions of stars mass, out Sagittarius way.
Next up, we have the "Local Cluster" which orbits its center of mass. Next comes groups, then clusters, and finally super-clusters. All arrayed in a frothy structure much like the bubbles in baby's bubble bath.
Assuming that gravity behaves as we think it does, everything from the smallest meteorite to the clusters at the furthest edge of the Universe must be gravitationally bound and there must be a center of mass for the Universe. There may be nothing there but a very good vacuum but somewhere there will be a center of mass of the Universe.
Of course, if gravity does not behave as we think it should, all bets are off. But if our theories are correct and man-not-so-kind survives long enough and makes enough observations the presence and location of the Center will become obvious.
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Post by byz on Sept 8, 2008 6:39:59 GMT
Well they are predicting frost on the UK.
This is about a week earlier than the long term average.
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Post by dopeydog on Sept 8, 2008 16:35:27 GMT
A source for the center of mass of the Universe? After sixty years titles escape me, so I would not try to remember the name of that astronomical tome. It was in blue covers, ran around 1200 pages and smelled like dust. And I was probably the first person to open it after the librarian put a number on its spine. But consider: Everything in this solar system rotates around the center of mass of the system. So much so the that Sun wobbles a bit and the CM is frequently outside the photosphere. It is much the same with our Galaxy. Which supposedly at least rotates around a center of mass colocated in a humongous black hole with a few tens of millions of stars mass, out Sagittarius way. Next up, we have the "Local Cluster" which orbits its center of mass. Next comes groups, then clusters, and finally super-clusters. All arrayed in a frothy structure much like the bubbles in baby's bubble bath. Assuming that gravity behaves as we think it does, everything from the smallest meteorite to the clusters at the furthest edge of the Universe must be gravitationally bound and there must be a center of mass for the Universe. There may be nothing there but a very good vacuum but somewhere there will be a center of mass of the Universe. Of course, if gravity does not behave as we think it should, all bets are off. But if our theories are correct and man-not-so-kind survives long enough and makes enough observations the presence and location of the Center will become obvious. Not questioning a center of mass for the universe, just that we orbit around it. Local phenomenom (which includes even super clusters) don't prove anything about the universe as a whole. I have never seen or read anything about the universe doing anything but expanding. And if it were rotating, how would we even know without a frame of reference.
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Post by ron on Sept 8, 2008 18:37:33 GMT
Universal rotation (and the resultant centrifugal force) could be the cosmological constant (fudge factor) or dark energy? As gravity loses the battle everything gets farther away from the center of the universe the expansion would seem to be accelerating. No? I'm not a physicist. Can we be rotating in 3 dimensions?
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Post by stranger on Sept 8, 2008 21:19:39 GMT
Mr. Dog, there will be some mighty unhappy physics theorists if the local group does not orbit the center of mass of the universe. But until we can improve the resolution of our instruments by a few orders of magnitude our efforts to determine proper motion of objects near the limit of our instruments is limited. And I am sure you know that the next best thing will a few centuries of observation.
But no, gravity is not likely to be dark matter. Or to be matter at all in any sense we know.
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Post by dopeydog on Sept 8, 2008 22:34:33 GMT
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Post by stranger on Sept 8, 2008 23:59:06 GMT
Killing time is for people younger and less occupied than I am. If I had any to kill I would add it to my sadly abbreviated sleep time.
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Post by jimg on Sept 9, 2008 5:24:09 GMT
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Post by ron on Sept 9, 2008 14:55:26 GMT
LOL
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Post by Ole Doc Sief on Sept 10, 2008 4:08:49 GMT
Boy I'd hate to go to the doctor with your weight problem. Can't imagine being told I need to lose a couple of super clusters.
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Post by dopeydog on Sept 10, 2008 16:49:48 GMT
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Post by woodstove on Sept 11, 2008 2:56:07 GMT
The low-temperature outlier is probably just that -- and yet...
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Post by dopeydog on Sept 11, 2008 16:11:32 GMT
A month ago the ensemble was just less than -.5. It has been steadily dropping ever since. And the weekly ENSO report is using more and more blue ink.
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Post by byz on Sept 14, 2008 18:49:18 GMT
It's started snowing in the north of Canada you can see it on CT !!! And the ice is growing back to Europe. My Tomatoes are getting late blight
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