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Serious blow to dark matter theories? New study finds mysterious lack of dark matter...
http://phys.org ^ | 04-18-2012 | Provided by ESO

Posted on 04/18/2012 12:11:06 PM PDT by Red Badger

Full title: Serious blow to dark matter theories? New study finds mysterious lack of dark matter in Sun's neighborhood

The most accurate study so far of the motions of stars in the Milky Way has found no evidence for dark matter in a large volume around the Sun. According to widely accepted theories, the solar neighbourhood was expected to be filled with dark matter, a mysterious invisible substance that can only be detected indirectly by the gravitational force it exerts. But a new study by a team of astronomers in Chile has found that these theories just do not fit the observational facts. This may mean that attempts to directly detect dark matter particles on Earth are unlikely to be successful.

A team using the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory, along with other telescopes, has mapped the motions of more than 400 stars up to 13 000 light-years from the Sun. From this new data they have calculated the mass of material in the vicinity of the Sun, in a volume four times larger than ever considered before.

"The amount of mass that we derive matches very well with what we see — stars, dust and gas — in the region around the Sun," says team leader Christian Moni Bidin (Departamento de Astronomia, Universidad de Concepcion, Chile). "But this leaves no room for the extra material — dark matter — that we were expecting. Our calculations show that it should have shown up very clearly in our measurements. But it was just not there!"

Dark matter is a mysterious substance that cannot be seen, but shows itself by its gravitational attraction for the material around it. This extra ingredient in the cosmos was originally suggested to explain why the outer parts of galaxies, including our own Milky Way, rotated so quickly, but dark matter now also forms an essential component of theories of how galaxies formed and evolved.

Today it is widely accepted that this dark component constitutes about the 80% of the mass in the Universe [1], despite the fact that it has resisted all attempts to clarify its nature, which remains obscure. All attempts so far to detect dark matter in laboratories on Earth have failed.

By very carefully measuring the motions of many stars, particularly those away from the plane of the Milky Way, the team could work backwards to deduce how much matter is present [2]. The motions are a result of the mutual gravitational attraction of all the material, whether normal matter such as stars, or dark matter.

Astronomers' existing models of how galaxies form and rotate suggest that the Milky Way is surrounded by a halo of dark matter. They are not able to precisely predict what shape this halo takes, but they do expect to find significant amounts in the region around the Sun. But only very unlikely shapes for the dark matter halo — such as a highly elongated form — can explain the lack of dark matter uncovered in the new study [3].

The new results also mean that attempts to detect dark matter on Earth by trying to spot the rare interactions between dark matter particles and "normal" matter are unlikely to be successful.

"Despite the new results, the Milky Way certainly rotates much faster than the visible matter alone can account for. So, if dark matter is not present where we expected it, a new solution for the missing mass problem must be found. Our results contradict the currently accepted models. The mystery of dark matter has just become even more mysterious. Future surveys, such as the ESA Gaia mission, will be crucial to move beyond this point." concludes Christian Moni Bidin.

More information: This research was presented in a paper, "Kinematical and chemical vertical structure of the Galactic thick disk II. A lack of dark matter in the solar neighborhood", by Moni-Bidin et al. to appear in The Astrophysical Journal.

Notes

[1] According to current theories dark matter is estimated to constitute 83% of the matter in the Universe with the remaining 17% in the form of normal matter. A much larger amount of dark energy also seems present in the Universe, but is not expected to affect the motions of the stars within the Milky Way.

[2] The observations were made using the FEROS spectrograph on the MPG/ESO 2.2-metre telescope, the Coralie instrument on the Swiss 1.2-metre Leonhard Euler Telescope, the MIKE instrument on the Magellan II Telescope and the Echelle Spectrograph on the Irene du Pont Telescope. The first two telescopes are located at ESO's La Silla Observatory and the latter two telescopes are located at the Las Campanas Observatory, both in Chile. A total of more than 400 red giant stars at widely differing heights above the plane of the galaxy in the direction towards the south galactic pole were included in this work.

[3] Theories predict that the average amount of dark matter in the Sun's part of the galaxy should be in the range 0.4-1.0 kilograms of dark matter in a volume the size of the Earth. The new measurements find 0.00±0.07 kilograms of dark matter in a volume the size of the Earth.


TOPICS: Culture/Society; Miscellaneous; News/Current Events; Technical
KEYWORDS: astronomy; energy; physics; space; stringtheory
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To: Lurker
If there’s as much “dark matter” in the universe as these scientists postulate my lawn should be covered with the stuff.

It is. That's not dog poo.

21 posted on 04/18/2012 12:27:23 PM PDT by Lazamataz (Shut up and drill.)
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To: muawiyah

‘Dark Matter’ is just a label, a name, to explain what the scientists don’t know...........The 21st century equivalent of ‘Aether’..............


22 posted on 04/18/2012 12:30:15 PM PDT by Red Badger (Think logically. Act normally.................)
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To: Red Badger

I’ve thought about that too. But obviously it’s not a possibility under consideration... and they are the “experts”...


23 posted on 04/18/2012 12:30:54 PM PDT by samtheman
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To: Red Badger

Next up, my Really Really Dark Matter Theory. I need a grant.


24 posted on 04/18/2012 12:31:01 PM PDT by Billthedrill
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To: Red Badger

Lots of words to say “we really don’t know much.”


25 posted on 04/18/2012 12:31:09 PM PDT by EternalVigilance (You can be a Romney Republican or you can be a conservative. You can't be both. Pick one.)
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To: Billthedrill

So far they have come up with Dark Matter and Dark Energy.

I guess the NEXT theory will be Dark Gravity.............


26 posted on 04/18/2012 12:33:25 PM PDT by Red Badger (Think logically. Act normally.................)
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To: muawiyah
Naw, it’s there alright ~ lots of it. We just haven’t figured out how to perceive it

So let me get this straight. This "dark matter" stuff exerts enough gravitational energy to keep the Universe from expanding forever but: It never seems to hit Earth even though Earth has it's own gravity. Somehow in all the billions of years Earth has been in existence they can't scrap ANY of the stuff off of ANYTHING. It's totally invisible except for it's gravitational influence. It emits no energy of any kind even when it's heated to millions and millions of degrees around stars and stuff. The dark matter theory has as much validity as AGW.

27 posted on 04/18/2012 12:33:25 PM PDT by Lurker (The avalanche has begun. The pebbles no longer have a vote.)
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To: Red Badger

First “they” come for the dark matter. And then “they” come for the rest of us.


28 posted on 04/18/2012 12:33:41 PM PDT by techcor (I hope Obama succeeds, in being a one term president.)
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To: Red Badger

LOL! That’s awesome!


29 posted on 04/18/2012 12:34:06 PM PDT by MNDude
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To: taterjay

But in science, being wrong is bad for you career..........


30 posted on 04/18/2012 12:35:04 PM PDT by Red Badger (Think logically. Act normally.................)
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To: Red Badger
Well dang, how could that be!
I mean we know everything about mass, gravity, the speed of light and the laws of physics here,
so they just have to apply precisely to the rest of the universe on a macroscopic scale………Right?
31 posted on 04/18/2012 12:36:10 PM PDT by The Cajun (Palin, Free Republic, Mark Levin, Newt......Nuff said.)
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To: cripplecreek

Where ever it is, when “O” finds it, he’ll tax it!


32 posted on 04/18/2012 12:37:06 PM PDT by SMARTY ("The man who has no inner-life is a slave to his surroundings. "Henri Frederic Amiel)
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To: Red Badger

Didn’t they come up with the theories of “dark” energy and matter in order to fudge the calculations that disproved some pet creation theory, like the Big Bang?

There are a couple more problems, I’ve heard, as well.
Where are the monopole magnets and the missing anti-matter?

Why can Hubble “see” further away, light-years-wise, than they estimate the universe is old?


33 posted on 04/18/2012 12:39:06 PM PDT by MrB (The difference between a Humanist and a Satanist - the latter knows whom he's working for)
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To: Red Badger

Well, I’m holding out hope. “It’s out there, I just can’t find it” is a perfectly viable state. It works for my car keys. And my sex life.


34 posted on 04/18/2012 12:42:48 PM PDT by Billthedrill
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To: Red Badger

Yup.

Purely a fudge factor.


35 posted on 04/18/2012 12:44:35 PM PDT by djf (If you are depressed all the time, at least you are never disappointed!)
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To: cripplecreek
This guy took it...


36 posted on 04/18/2012 12:47:13 PM PDT by Bigh4u2 (Denial is the first requirement to be a liberal)
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To: Red Badger
Ah yes, the aether that was so dramatically proved to exist by the Michelson-Morley experiment.

A fiasco soon to be eclipsed by the failure to discover the "God particle" a.k.a. the Higgs boson.

I love hubris! It's what makes our _resident so special.

37 posted on 04/18/2012 1:03:31 PM PDT by Aevery_Freeman (Typed using <FONT STYLE=SARCASM> unless otherwise noted)
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To: djf

The more we understand the less we know. I love my faith cause it has all the answers.


38 posted on 04/18/2012 1:09:20 PM PDT by Baseballguy (If we knew what we know now in Oct would we do anything different?)
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To: MrB
Where are the monopole magnets and the missing anti-matter?

Magnetic fields can send particles to infinity:

http://phys.org/news/2012-04-magnetic-fields-particles-infinity.html

39 posted on 04/18/2012 1:13:09 PM PDT by Red Badger (Think logically. Act normally.................)
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To: Baseballguy

About a year ago, I stumbled on an article, can’t remember where exactly.

They said there had been further, much more refined runs of the Michelson-Morley experiments and that they had indeed showed some kind of cosmic drift, or Zero-Point energy field related to spatial geometry, thus contradicting GR.

But once again the effect was so small you can’t hardly put your finger on it...


40 posted on 04/18/2012 1:15:27 PM PDT by djf (If you are depressed all the time, at least you are never disappointed!)
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