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Profile Jayargh
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Message 3853 - Posted: 9 Nov 2007, 5:15:48 UTC

In depth explanation from the scientist involved...

Galaxies are ever evolving systems that can provide insight into how the universe came to be what it is now. One thing we have learned about galaxies is that they often merge into larger galaxies. We know this because we can observe it (e.g. here and here). However, there is only so much you can learn by looking at these mergers since we only see a two dimensional projection. Therefore, we are going to study the Milkyway since it is the only galaxy where we can study in all three dimensions. We are also in luck for in 1994 Rodrigo Ibata discovered that the Milkyway was currently merging with another galaxy: the Sagittarius (Sgr) Dwarf Ellipsoidal Galaxy. Due to its relative small size compared to the Milkyway, the Sgr dwarf is being tidally disrupted. This means that due to the Milkyway's much stronger gravitational force the Sgr dwarf is being ripped apart and drawn out into long tidal streams that lead and follow the actual core of the Sgr dwarf. You can see a simulation of this disruption and get a better understanding of it here. This tidal debris gives us a unique insight into our Galaxy. In general, we can only tell where a star is and where it is going. However, by studying these streams we can see where the stars were. In this way streams leave a map that allow us to be able to study the gravitational potential of the Milkyway. Also, since the potential is an estimated 90% due to dark matter we will be able to get a good handle on the distribution of the dark matter within the Milkyway.

It is this tidal debris that we be studying using Milkyway@home. We have developed a method to be able to isolate and determine the properties of this debris. We also do not plan to limit ourselves to simply studying known streams (this will be the first step though), but to also be able to discover/study new pieces of tidal debris.

Somewhat similar to Cosmo on a local scale.Dark matter analysis is a major objective here.

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Profile Martin Beltov

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Message 3854 - Posted: 9 Nov 2007, 8:40:11 UTC

Sounds really interesting
Thank you very-much for the information
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Message 4194 - Posted: 7 Dec 2007, 6:04:36 UTC - in response to Message 3853.  

In depth explanation from the scientist involved...

Direct link
me@rescam.org
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Message 4200 - Posted: 7 Dec 2007, 21:32:06 UTC

I believe that \"dark matter\" is the name we have given to our ignorance of the laws of gravity. I am convinced that those laws are considerably more complex than has been recognized and look forward to the day when this dark matter is illuminated (pun intended).

Ditto \"dark energy\".
In the beginning, there was nothing, which exploded.
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Profile Benjamin Wandelt
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Message 4213 - Posted: 9 Dec 2007, 0:21:36 UTC - in response to Message 4200.  

I believe that \"dark matter\" is the name we have given to our ignorance of the laws of gravity. I am convinced that those laws are considerably more complex than has been recognized and look forward to the day when this dark matter is illuminated (pun intended).

Ditto \"dark energy\".


It\'s funny, but I had exactly the same reaction when I first heard about dark matter and I know that many of my colleagues felt the same. But no one has been able to explain all available data with a theory that is as simple as GR and does not contain dark matter.

Even if it were possible to explain everything we know without dark matter and dark energy in terms of \"considerably more complex\" laws of gravity - would that be necessarily better? The search for a fundamental theory is also the search for beauty in simplicity.

In any case, there is hope. The Large Hadron Collider will come online next year, Planck will fly, huge astronomical surveys will chart the observable Universe, and many other experiments will continue to probe the laws of physics.

We might yet \"see\" dark matter in detectors or even produce it at the LHC. Then only dark energy remains and the explosion of astronomical data that is already beginning to happen may give us just the clues we need.

All the best,
Ben

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Message 4219 - Posted: 9 Dec 2007, 2:49:39 UTC

Ben, thanks for the response. As to the gravity issue, I am excited about MOND and the TeVeS extensions. I think that is the way forward, even if it doesn\'t entirely satisfy Occam\'s Razor. I don\'t believe Newton had the whole picture.

I am no scientist by a long shot, just an amateur enthusiast who likes playing with computers. Thinking about this stuff makes my head hurt, so I just crunch the numbers and let you guys do the heavy lifting.

Keep up the good work!
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Message 4240 - Posted: 12 Dec 2007, 3:09:55 UTC - in response to Message 4213.  

Then only dark energy remains and the explosion of astronomical data that is already beginning to happen may give us just the clues we need.


From someone who knows very little about the current state of astronomy, could you explain more about this \"explosion of astronomical data\"?
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Profile Benjamin Wandelt
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Message 4252 - Posted: 12 Dec 2007, 23:46:51 UTC - in response to Message 4240.  

Then only dark energy remains and the explosion of astronomical data that is already beginning to happen may give us just the clues we need.


From someone who knows very little about the current state of astronomy, could you explain more about this \"explosion of astronomical data\"?


Hi Zachary -

New technology and the ability to put telescopes in space have increased the amount of new astronomical data at a rate that is larger than Moore\'s law.

We all are privileged to live in that time where humankind maps the observable part of the cosmos and discovers its geometry, content and large scale structure, just like generations before us that mapped and discovered the spherical geometry of the Earth.

Wanting to be a part of that discovery is what made me decide to become a cosmologist.

I hope I can share some sense of my excitement about this ongoing discovery through Cosmology@Home.

All the best,
Ben

Creator of Cosmology@Home
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