A simulation of the evolution of the universe suggests that it is expanding at an accelerating rate. This is more evidence for the existence of Einstein’s cosmological constant a kind of gravitational pressure in space that acts against the attraction due to mass.
Last year the Virgo consortium carried out the largest computer simulation ever, modelling the evolution of some 1 billion particles. The consortium groups astronomers from Canada, Germany, the UK and the US and it is led by Carlos Frenk at Durham University in the UK.
The Durham group has now used the Virgo simulation to explain observations of real galaxies. It used models of galaxy formation together with the distribution of matter predicted by the simulation.
“This is the first time that we have had a theory that matches the observed distribution of clustering”, said Frenk. “Its amazing. I couldn’t believe it when I first saw it!” However, to get a perfect match, they needed to use a non-zero cosmological constant.
This is not the first time that observations have implied the existence of a cosmological constant. Supernova studies (CERN Courier May) have also hinted at this and Frenk says that his results are “beautifully consistent”. The group is trying to test its result by carrying out an additional simulation in parallel, this time including both dark matter and gas. First indications are in agreement, but there is a greater margin of error.
The Virgo supercomputer simulations were carried out at the MaxPlanck centre in Garching, Germany, and the Edinburgh computer centre in the UK.
