Cosmic Computing
Simulating the universe
Ron Cowen
To see the light, you sometimes have to journey through darkness. That
aphorism, it seems, applies not only to journeys of the heart but also to
excursions through the history of the universe. In the largest and most
detailed computer simulation of this cosmic saga, something utterly dark
shapes the universe as it unfolds over some 13.7 billion years.
That new simulation traces the fate of the universe's original stocks of
energy and matter from just a few hundred thousand years after the Big Bang
to the present.
To make sense of the arrangement of starlit galaxies and brilliant quasars
across the sky, Volker Springel of the Max Planck Institute for Astrophysics
in Garching, Germany, and his colleagues based their work on dark matter.
That invisible material accounts for more than 90 percent of the gravity
within the universe.
Although no one knows what dark matter is made of, researchers suspect that
it's responsible for pulling galaxies and galaxy clusters into the
gargantuan, filamentary structures seen in the sky today. Because dark
matter doesn't seem to interact with any force other than gravity, it's
relatively simple to model. Springel's team built 10 billion clumps of the
stuff into its simulation.
The modelers laid onto this canvas of dark matter a rough approximation of
some of the messy and complex interactions between galaxies, such as the
eruption of supernova explosions and the trajectories of powerful
intergalactic winds. With that, the researchers could explore how the larger
structures in the universe-both invisible ones such as dark matter and
visible ones such as galaxies-evolved over billions of years.
As described in the June 2 Nature, the model confirms recent findings that
the expansion of the universe has sped up. It also suggests a scenario for
the surprisingly rapid growth of supermassive black holes-the powerhouses
that fuel quasars-early in the history of the cosmos.
The new work "gives us the most detailed and accurate theoretical
predictions so far of the properties of galaxies from the dawn of cosmic
time to the present day," comments Nickolay Gnedin of the University of
Colorado in Boulder.
Full Text at ScienceNews
http://www.sciencenews.org/articles/20050813/bob9.asp
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Posted by
Robert Karl Stonjek
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