Simulating the Whole Universe

Roland Piquepaille writes "An international group of cosmologists, the Virgo Consortium, has realized the first simulation of the entire universe, starting 380,000 years after the Big Bang and going up to now. In 'Computing the Cosmos,' IEEE Spectrum writes that the scientists used a 4.2 teraflops system at the Max Planck Society's Computing Center in Garching, Germany, to do the computations. The whole universe was simulated by ten billion particles, each having a mass a billion times that of our sun. As it was necessary to compute the gravitational interactions between each of the ten billion mass points and all the others, a task that needed 60,000 years, the computer scientists devised a couple of tricks to reduce the amount of computations. And in June 2004, the first simulation of our universe was completed. The resulting data, which represents about 20 terabytes, will be available to everyone in the months to come, at least to people with a high-bandwidth connection. Read more here about the computing aspects of the simulation, but if you're interested by cosmology, the long original article is a must-read."

Comments

Tree / Multipole expansion

[Anonymous Coward]

The article indicates that the "tricks" these researchers used were the octree and multipole expansion--both of which have been used in gravity and potential theory for many years. They reduce the N^2 interaction problem to N or N Log(N), depending upon implementation. The story makes it sound like these researchers invented the technique; I assume the writer misunderstood the scientists, because it certainly predates them.

Re:Kind of useless?

[mangu]

I think they would've done a much better job with 1 million particles of possibly different types, simulating several other forces.

No. Of the four known forces in the universe, only gravity is important in the long range, which defines the overall structure of the universe.

The other three forces are electrical, and two nuclear forces. The nuclear ones are *very* short range, acting only in the atom nucleus. The electrical force is long range, but because there are two different electrical charges, which balance out, there isn't any perceptible electrical attraction in the long range.