The measurements were made by Ed Pomelont of the National Radio Astronomy Observatory in Charlottesville, Virginia and Sergey Kopeikin of the University of Missouri in Columbia
The speed of gravity was measured for the first time and it turned out to be equal to the speed of light. This means that Einstein's theory of general relativity passed another test successfully.
The measurements were carried out by Ed Fomalont (from the National Radio Astronomy Observatory in Charlottesville, Virginia) and Sergey Kopeikin from the University of Missouri in Columbia. In an article in New Scientist they wrote: "We became the first two people to know the speed of gravity, one of the basic constants of nature.
In the experiment, scientists from the University of Columbia together with astronomers working at the radio telescope in the state of Virginia made very precise measurements of the curvature caused by radio rays emitted from a distant star (quasar) while the planet Jupiter "passes by them". The result the scientists got was actually 0.95 percent of the speed of light, but the accuracy level of the experiment was not high enough and therefore the scientists concluded that it was probably the speed of light.
Physicist Isaac Newton believed that the force of gravity acts instantaneously between bodies. If the sun for example were to disappear suddenly the earth would be affected immediately. Einstein believed that the effect of gravity is limited to the speed of light and incorporated this principle into his general theory of relativity. From this it follows that if the sun were to disappear suddenly, a period of approximately 8 minutes would pass (the time it takes for a light beam to travel the distance between the sun and the earth) before the effect of gravity would cease.
Modern physical theories (certain versions of string theory for example) have again raised doubts about the speed of gravity. The last experiment showed that the approach advocating gravity moving at the speed of light is probably the correct one.
The results of the study were presented at a conference of the American Astronomical Society in Seattle.
