Intercontinental supercomputer unravels the structure of the universe
- An international team of astrophysicists and computer scientists headed by Professor Simon Portegies Zwart, has successfully carried out a large-scale calculation using two linked computers. The team intends to use the calculation to chart the large structures of dark matter.
Visualisation of dark matter
- CosmoGrid
- Under the supervision of Portegies Zwart of the Leiden Observatory and following a preparation time of almost a year, the Dutch Huygens supercomputer and the Cray XT4 in Tokyo have successfully carried out the first 3,644 of the total of 100,000 planned calculation steps. The universe has been 'divided' between the two supercomputers within the CosmoGrid. After each step in the calculation, the two computers have to be synchronised. This is the equivalent of sending an Encyclopaedia Britannica of data to Tokyo, and vice versa.
- The pyramids of Giza at Cairo are visible as ordinary matter, but if our eyes were sensitive to dark matter, the night sky would look roughly the same as this image. The night sky above the pyramids is the result of an initial trial calculation by the CosmoGrid.
- Intermediate junctions
- To be able to transmit this huge datastream efficiently, the supercomputers in Amsterdam and Tokyo are linked by means of a separate, superfast optical network that connects the academic calculation centre SARA via 11 intermediate junctions (including New York, Chicago and Seattle) with Tokyo. Among other systems, the Amsterdam NetherLight GLIF Open Lightpath Exchange (GOLE) of SURFnet is used.
- WIMPs
- CosmoGrid models the structure of the dark matter in the universe with a record number of some 10 billion particles. The greatest part of the universe comprises dark energy and dark matter. Dark matter is matter that exercises gravitational force, but does not transmit any discernible radiation. According to one of the theories, dark matter consists of massive particles, so-called WIMPs, that interact weakly.
- The two supercomputers are linked via a primary and a secondary intercontinental lightpath. Both lightpaths run, via the US, along the floor of the Atlantic Ocean and the Pacific Ocean to Japan. The light path travels via 11 intermediate stations and passes networks of GLIF Open Lightpath Exchanges Netherlight in Amsterdam, the StarLIght TransLight/StarLight link in Chicago, Pacific Northwest Gigapop in Seattle en T-Lex in Tokyo.
- Breakthrough
- Project leader Portegies Zwart has described CosmoGrid as a ‘breakthrough' in distributed calculation: 'At the moment we have achieved almost 90% of the maximum calculation capacity of the two computers.' The research team expects that within a short time optical networks with their specific characteristics will make possible many more such large-scale calculations via international co-operation between supercomputers.
The total calculation will take about a year. And it will take about six million hours of computer time. Scientists from the Netherlands, Japan, the US, Scotland and Germany are taking part in the research.
This report appeared on Wednesday 3 June as a press release by the Netherlands Research School for Astronomy (NOVA).
(9 june 2009)
