An international team of scientists has conducted a 16-year experiment to put the theory of general relativity through one of the most rigorous sets of tests ever. The study by seven radio telescopes of a single pair of stars at the end of their lives (pulsars) reveals new relativistic effects predicted by the theory but never before observed. The observations made are moreof 99.99% consistent with Albert Einstein's theory.

More than 100 years after Albert Einstein presented his theory of gravity, scientists around the world continue to search for flaws in General Relativity. Any observed deviation from his predictions could be a clue to a new physics capable of unifying theories describing the infinitely small world (quantum world) and the largest scales.

To do this, an international team led by the Max Planck Institute for Radio Astronomy studied a unique system of two pulsars orbiting each other - very compact, highly magnetized, rapidly rotating stars that produce beams of radio waves that sweep across the sky like beacons. All these features make this system an ideal laboratory for testing general relativity.Discovered in 2003, it was observed for 16 years with seven radio telescopes.

All the data collected (about a million precisely timed radio pulses) allowed scientists to detect numerous relativistic effects and to measure seven parameters of the theory of General Relativity, some of them in a way never done before. One example: the strong gravitational field of each fast-moving pulsar bends space-time around it and thus shifts the path of theradio waves emitted by the other pulsar. Not only is the signal detected by telescopes later than if it were propagating in a straight line, but the minute angle of this deviation (0.04 degrees) could be determined for the first time.

The scientists were also able to test a cornerstone of Einstein's theory, the emission of gravitational waves (small oscillations in space-time), with a precision 1000 times greater than that currently possible with direct detection by gravitational-wave detectors. They also observed a consequence of the famous equation E = mc² : pulsar radiation is accompanied by a loss of mass - or the dilation of time, which runs more slowly in the presence of a strong gravitational field.

All observations were made in agreement with Einstein's theory. If scientists really want to find a flaw in General Relativity, even more ambitious tests will be needed. But one thing we can be sure of: until that happens, or if it really happens, Albert Einstein will remain a genius.