Slashdot Mirror
Scientists Complete Universe Millennium Simulation
james tech writes "The Virgo Consortium recently completed its massive "Millennium Simulation", tracing the universe's evolution from its early origins to present day. To simplify the computations, they considered only dark matter which composes most of the universe. Using a 512-node cluster with IBM processors, the group produced over 20 terabytes of data with some of the most breathtaking images of the universe never seen. A visible matter simulation is underway, at a lower resolution."
a good one is gravitational lensing by massive clusters -- a lens analysis of all the arcs seen in, for example, a cluster, can be used to infer the mass of the cluster, and hence see that it is inconsistent with the mass of all the luminous matter. i.e. dark matter
Full Text Just incase
All spelling mistakes are due to solar flares...honest
http://www.mirrordot.org/stories/bdfc0ad7cef604a1a f6b98722b0f530f/index.html
Sigs are for the weak.
I managed to download one of the videos the instant the story appeared but we desperately need someone to put torrents for them. The site was pretty well dead by the time there were even TWO Slashdot posts.
The video I got was pretty impressive at 1024 full screen mode. I haven't been able to get the other one.
-
- - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
Server timing out.
9 8722b0f530f/index.html
Suggest people who want to see the pretty pictures use the Mirrordot mirror link at
http://mirrordot.org/stories/bdfc0ad7cef604a1af6b
Also, by measuring the expansion rate of the universe over a very long time (ie. billions of years), and making observations of the Cosmic Microwave Backgound (CMB, the left over radiation from around 300000 years after the Big Bang) we can calculate the amount of matter it must contain. Then from models of the Big Bang and the CMB observations we can also find the amount of 'normal' matter (ie atoms), which comes to about 4% of the so called 'critical density', which is the amount of matter/energy required to have the universe be spatially flat (expands forever but tends toward zero expansion rate as time goes to infinity)
Since the amount of matter is measured to be around 25% this means dark matter must be around 20% of the critical density.
Incidentally, this also means that 75% of the energy/matter in the universe is 'dark energy', since the cosmic microwave background indicates the universe is almost exactly flat.
However, the importance of each constituent changes over time because essentially the dark energy is proportional to the size of the universe and when it was much smaller the matter was more concentrated so it had a far greater influence. Therefore for studies of the early evolution of the universe the dark energy is unimportant, and since dark matter is most of the total matter the models can just use dark matter alone. At present, however, the dark energy appears to be causing an acceleration of the expansion rate, which is seen using distant supernovae. This is how the 75% figure is worked out.
NB: Nobody can explain what the dark matter or dark energy is right now! This is by far the most important problem in Cosmology, and there are many , many competing theories.
happy downloading
(paraphrase) "Celestial Navigation works on the principle that the Earth is the center of the universe. The assumption is wrong, but the navigation works. A flawed model can still produce useful results."
All models are oversimplifications. Even our models of molecules pretend that atoms are solid spheres... This doesn't mean that the models are useless.
That said, only time will tell how useful this model is.
Zapman
Your question is meaningless. There is no "before" the big bang, because time AND space began at that point. "Prior" to the big bang is about as meaningful as asking what point on the Earth's surface is the center of the world.
There is no known way--and likely never will be--to know anything about existance outside of the post-big bang observable universe, other than indulging in wild and baseless speculation.