Pioneers track galactic evolution

Astrophysicists have crossed one of the final frontiers of understanding the evolution of the universe using an unprecedented amount of computing power, writes Aisling Irwin.

The mainly British group has confirmed theories about the state of the universe at 100,000-years-old by simulating the latest discoveries on a computer.

Using the model they fast forwarded the evolution up to the present day and found that the model was the same as the real universe.

The work was done on the Cray- T3D parallel supercomputer installed at Edinburgh university in 1994. The computer is capable of up to 50 gigaflops - the largest in Europe.

The modelling, done by a group known as the Virgo consortium, is the latest step in unravelling the evolution of the universe. Since the late 1970s, particle physicists had believed that the embryo universe went through an abnormally rapid phase of growth which would have caused tiny fluctuations in the cosmic energy density. Then, in 1992, the Cobe satellite detected tiny ripples in the relic radiation, just as predicted.

Led by Carlos Frenk, professor of physics at Durham University, the Virgo group fed the properties of these newly discovered ripples into the computer as initial conditions. They then ran a simulation of the growth of these ripples.

Professor Frenk told the United Kingdom National Astronomy Meeting in Liverpool this week: "This is the first time that a calculation has been capable of following the formation of galaxies in their entire cosmic environment. We were able to take into account the huge cosmic volume. What is happening billions of light years away has an influence".

As the simulation progressed the ripples grew chaotically. Lumps of matter collapsed and merged with neighbouring lumps. By the end of the simulation there was a pattern of large filaments surrounding vast empty regions. These filaments represent the distribution of mass in our universe. In between the filaments are small clumps of rotating material - the galaxies.

Professor Frenk, who worked with scientists from Sussex, Oxford, Cardiff and Toronto universities and the Max Planck Institute for astrophysics, likened the work to finding "the fossil record of the missing link. Imagine you could do a computer simulation that would take the fossil record and evolve it until we see the human growing".