Scientists use world's fastest supercomputer to model origins of the unseen universe

Oct 26, 2009

Understanding dark energy is the number one issue in explaining the universe, according to Salman Habib, of the Laboratory's Nuclear and Particle Physics, Astrophysics and Cosmology group.

"Because the universe is expanding and at the same time accelerating, either there is a huge gap in our understanding of physics, or there is a strange new form of matter that dominates the universe - 'dark energy' - making up about 70 percent of it," said Habib. "In addition, there is five times more of an unknown 'dark matter' than there is ordinary matter in the universe, and we know it's there from many different observations, most spectacularly, we've seen it bend light in pictures from the , but its origin is also not understood."

Even though it's looking at only a small segment of the "accessible" universe, Habib's "Roadrunner Universe" model requires a petascale computer because, like the universe, it's mind-bendingly large. The model's basic unit is a particle with a mass of approximately one billion suns (in order to sample galaxies with masses of about a trillion suns), and it includes 64 billion and more of those particles.

The model is one of the largest simulations of the distribution of matter in the universe, and aims to look at galaxy-scale mass concentrations above and beyond quantities seen in state-of-the-art sky surveys.

"We are trying to really understand how to more completely and more accurately describe the observable universe, so we can help in the design of future experiments and interpret observations from ongoing observations like the Sloan Digital Sky Survey-III. We are particularly interested in the Large Synoptic Survey Telescope (LSST) in Chile, in which LANL is an institutional member, and DOE and NASA's Joint Mission (JDEM)," said Habib. "To do the science in any sort of reasonable amount of time requires a petascale machine at the least."

The Roadrunner Universe model relies on a hierarchical grid/particle algorithm that best matches the physical aspects of the simulation to the hybrid architecture of Roadrunner. Habib and his team wrote an entirely new computer code that aggressively exploits Roadrunner's hybrid architecture and makes full use of the PowerXCell 8i computational accelerators. They also created a dedicated analysis and visualization software framework to handle the huge simulation database.

"Our effort is aimed at pushing the current state of the art by three orders of magnitude in terms of computational and scientific throughput," said Habib. I'm confident the final database created by Roadrunner will be an essential component of dark universe science for years to come."

Source: Los Alamos National Laboratory (news : web)

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User comments : 5

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frajo
3.4 / 5 (5) Oct 26, 2009
Because the universe is expanding and at the same time accelerating, either there is a huge gap in our understanding of physics, or there is a strange new form of matter that dominates the universe

Or the premise "accelerated expansion" is false. But this kind of logical reasoning seems to be taboo for some people. Wonder why.
Archivis
2.3 / 5 (3) Oct 26, 2009
"either there is a huge gap in our understanding of physics, or there is a strange new form of matter that dominates the universe"

Yes because we are so infailable that it couldn't possibly be the first one...
Torbjorn_Larsson_OM
5 / 5 (3) Oct 26, 2009
@ frajo, Archivis:

It is not taboo at all, nor a premise, nor infallible - it's a result. It's precisely why research have tested this explanation among others, that it remains. You can wiki the "Lambda-CDM" model and find references to get you started on the matter.
frajo
2.3 / 5 (3) Oct 26, 2009
It's precisely why research have tested this explanation among others, that it remains.

Seems that not all researchers agree with that position.

You can wiki the "Lambda-CDM" model and find references to get you started on the matter.

Thanks a lot. You can wiki for "cyclic model" or for "Randall-Sundrum model". Not to get you started though. :)
jgelt
Oct 26, 2009
This comment has been removed by a moderator.
E_L_Earnhardt
1 / 5 (1) Oct 27, 2009
Think "ELECTRONS" and you will be closer to understanding "Dark Matter"!

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