Simulating the Universe with a zBox

An anonymous reader writes "Scientists at the University of Zurich predict that our galaxy is filled with a quadrillion clouds of dark matter with the mass of the Earth and size of the solar system. The results in this weeks journal Nature, also covered in Astronomy magazine, were made using a six month calculation on hundreds of processors of a self-built supercomputer, the zBox. This novel machine is a high density cube of processors cooled by a central airflow system. I like the initial back of an envelope design. Apparently, one of these ghostly dark matter haloes passes through the solar system every few thousand years leaving a trail of high energy gamma ray photons."

Comments

Re:I don't understand...

[Sique]

The problem in question is the number of distinguishable bodies. With weather you would have to go down to the single molecule in the air, to get a quite good prediction. In fact current weather models use cubes of air where the conditions are considered constant (same temperature, same pressure, same direction of air flow in the same cube) and take them as distinguishable bodies. Those models are a compromise between the sheer number of necessary elements, the number crunching limits of current calculation hardware and the difference between the used model and the reality.

With stellar bodies it's much more easy. The number of stellar bodies you need for a prediction is much smaller, the bodies themself can be considered almost constant for the whole calculation etc.pp. With the number crunching capacity of today's weather prediction centers you can simulate whole galaxies (if you consider stars constant, which they mainly are for about 10mio to 10bio years, depending on their mass). With the differences between your model and the measured reality you can spot elements you didn't simulate yet and add them to your model. The swiss team now was simulating clouds of about the mass of the earth and the size of the solar system and found that those added to the stellar simulation made a quite good fit to the measured data.