Insight into the light speed hypothesis

Chinese scientists say evidence based on data gleaned from eclipses and Earth tides support the hypothesis that gravity travels at the speed of light. Researchers at the Institute of Geology and Geophysics of the Chinese Academy of Sciences said six observations of total and annular solar eclipses, as well as records of Earth tides, showed gravitational force released from the sun and gravitational force recorded at ground stations on Earth did not travel at the same speed. The time difference exactly matched the time it takes light to travel from the sun to observation stations on Earth, they said. By applying the data to equations concerned with the propagation of gravity, the team obtained a speed of gravity of about 0.93 to 1.05 times the speed of light, with a relative error of about 5 percent -- providing the first set of strong evidence showing that gravity travels at the speed of light, China's state-run Xinhua news agency reported. Scientists who have been trying to measure the speed of gravity for years with experiments and observations have been struggling to come up with valid methods, Xinhua said. The findings are set to be published in the Chinese Science Bulletin.