Astronomers have used a pair of pulsars orbiting each other, found with CSIRO’s Parkes telescope in 2003, to show that Einstein’s theory of general relativity is correct to within 0.05% – the most stringent limit to date.
They also hope to be able to use the two pulsars to determine the exact nature of the matter that pulsars and other neutron stars are made of.
Their results are to be published in the journal Science, and made available online in Science Express on 14 September 2006 (http://www.sciencemag.org/cgi/content/abstract/1132305v1).