nyc_nurse
sage
Reged: 07/29/09
Posts: 254
Loc: nyc
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Interesting article in the NYTimes.
Is it going to checkout or is it going to fizzle like "cold fusion."
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Sam P.
www.agirlandaguy.blogspot.com
Pentax 7X50
TV-102 APO w/ (Starbeam - on backorder  )
Ash Gibraltar w/ SkyTour DSC
NZ3-6, N9T6, N13T6
TV 20 Plossl
Pan 24, 35
Pentax XW10, XW14
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b1gred
Enginerd
Reged: 04/01/04
Posts: 15715
Loc: Castle Rock, CO 6677' MSL
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It's an interesting concept, and it would be cool if they can prove it via indirect observation.
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"Dark Skies & Great Viewing"
RandyR / W0RDR
GPS 9.25 XLT/Sky Align /FeatherTouch
TV85 w/FeatherTouch
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RonBurgundy
sage
Reged: 06/16/09
Posts: 271
Loc: Philadelphia
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This is nothing short of phenominal... Wow!!!!!!
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Kipp Ginsburg
8" LX200-ACF
Orion 120mm F/5.0 Piggybacked Refractor
Meade UWA Set [4.7mm-30mm]
DSI-II
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HiggsBoson
Pooh-Bah
Reged: 02/21/07
Posts: 1118
Loc: Kal-li-fornia
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The link does not work for me. However, I am among those who accept the shot of the two colliding galaxies as showing a separation between Dark and Baryonic matter. This shot was taken by the Chandra X-Ray Space Telescope and some other ground based instrument. It was published in 2006.
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Michael
ATM: 6" F/9 Newtonian Travel Scope
ATM: 12.5" F/4.5 Real Soon Now...
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ragebot
Carpal Tunnel
Reged: 08/26/05
Posts: 1672
Loc: Tallahassee, FL, USA
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Quote:
The link does not work for me. SNIP
The link basically said the paper was designed to be sorta milk toast; and there would be a following paper with stronger claims about dark matter. There was also some comments from a well respected researcher who thinks this is not that big a deal.
I don't have the smarts to confirm or deny this shows evidence of dark matter; but my take is the paper is a step in the right direction but not a smoking gun.
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Meade ETX 90, Meade AR5, Orion ED80, Atlas GT, 8 in Newt, Coronado DS SM40, Garrett 10.5X70, Sigma SD10, SD14, Canon 1D2, Xti, Nikon CP4500, C-14
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HiggsBoson
Pooh-Bah
Reged: 02/21/07
Posts: 1118
Loc: Kal-li-fornia
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My point was that a smoking guy was found back in 2006.
http://en.wikipedia.org/wiki/Bullet_Cluster
The photo was taken of the Bullet Cluster which shows two colliding galaxies. It shows that the center of Baryonic mater is in a different location than the center of mass. Visible shows the baryonic matter and X-Ray shows gravitational lensing of an object behind the cluster. The lensing indicates that the largest mast is not in the location as the normal matter.
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Michael
ATM: 6" F/9 Newtonian Travel Scope
ATM: 12.5" F/4.5 Real Soon Now...
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ragebot
Carpal Tunnel
Reged: 08/26/05
Posts: 1672
Loc: Tallahassee, FL, USA
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Quote:
My point was that a smoking guy was found back in 2006.
http://en.wikipedia.org/wiki/Bullet_Cluster
The photo was taken of the Bullet Cluster which shows two colliding galaxies. It shows that the center of Baryonic mater is in a different location than the center of mass. Visible shows the baryonic matter and X-Ray shows gravitational lensing of an object behind the cluster. The lensing indicates that the largest mast is not in the location as the normal matter.
There is a difference between "a smoking gun" and "the smoking gun". Another explanation is that the gravity model being used does not fit the matter we are seeing.
There is a school of thought that dark matter is just a confusing way of saying "we got gravity wrong".
I don't find it very elegant to say the only way to explain the model we are using is by postulating we can only see ~5% of the stuff out there and the rest is dark matter and dark energy.
If I was forced to make a call I would probably say there is "something" out there AND the model is wrong.
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Meade ETX 90, Meade AR5, Orion ED80, Atlas GT, 8 in Newt, Coronado DS SM40, Garrett 10.5X70, Sigma SD10, SD14, Canon 1D2, Xti, Nikon CP4500, C-14
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Glaucus
member
Reged: 07/12/09
Posts: 45
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The point is that the Bullet clusters is where all variants of MOND totally fail.
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 709
Loc: Rodeo, NM
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Quote:
There is a school of thought that dark matter is just a confusing way of saying "we got gravity wrong".
I don't find it very elegant to say the only way to explain the model we are using is by postulating we can only see ~5% of the stuff out there and the rest is dark matter and dark energy.
I've made this point before, but this looks like a good place to make it again ...
Suppose we dismiss dark matter and dark energy, and just try to explain it all away with a modified theory of gravity. What you'd need, then, is a "gravitational force" that follows an inverse-square law at stellar distance scales, becomes *stronger* than inverse-square at galactic distance scales (to explain away dark matter), and then switches gears completely and turns into a *repulsive* force at cosmological distance scales (to explain away dark energy).
And then, of course, gravity has to do something else yet again at the quantum level.
ragebot makes the point that he thinks the correct solution may be a mixture of modified gravity and new phenomena, and that may very well be correct.
My own point is that rejecting dark matter and dark energy entirely and depending on modified gravity to perform the tricks does not appear to be a good bet.
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Terry (astrotrf)
Edited by astrotrf (11/01/09 05:40 AM)
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HiggsBoson
Pooh-Bah
Reged: 02/21/07
Posts: 1118
Loc: Kal-li-fornia
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It is also the case that without Dark Energy and Dark Matter one must find a way to explain the measured mass/energy density of the universe. The dark matter and dark energy postulates fit a wider scope of observed phenomena that just explaining the rotation of galaxies. Moreover the theory predicted Dark Energy. It was a bias about the stability of the universe that caused a very smart person to hide this prediction by the introduction of a cosmological constant. The dark energy postulate is supported by theory which is based upon postulates unrelated to the galactic rotation problem.
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Michael
ATM: 6" F/9 Newtonian Travel Scope
ATM: 12.5" F/4.5 Real Soon Now...
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 709
Loc: Rodeo, NM
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Indeed. In fact, I find it interesting and perhaps revealing that MOND theories are dropping by the wayside, one after another, based on observation, while the cosmological constant remains consistent with observation.
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Terry (astrotrf)
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Glaucus
member
Reged: 07/12/09
Posts: 45
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It's not cosmological constant/dark energy here. But dark matter.
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HiggsBoson
Pooh-Bah
Reged: 02/21/07
Posts: 1118
Loc: Kal-li-fornia
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Yes, but dark energy, dark matter, radiation and baryonic mater make up pieces of a larger picture. If one decides to replace dark matter with gravity one must no adjust other areas of cosmology. The fact that dark matter fits into the larger framework supports the dark matter postulate.
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Michael
ATM: 6" F/9 Newtonian Travel Scope
ATM: 12.5" F/4.5 Real Soon Now...
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