Great scientist, Elbert Einstein has proposed total three tests of general relativity which are known as classical tests, introduced in 1916. These three important tests of general relativity comprise the perihelion precession of Mercury’s orbit, the deflection of light by the Sun and the gravitational redshift of light. Then there are modern testing of general relativity laid down by Dicke and Schiff. Modern era of testing focuses not only on classical tests but also on the importance of effects of testing on a theory of gravitation and some null experiments. Present day tests of general relativity include Light travel time delay testing, Gravitational lensing, Post-Newtonian tests of gravity Frame-dragging tests, Strong field tests: Binary pulsars, direct detection of gravitational waves, Cosmological tests and the equivalence principle.
The perihelion precession of Mercury’s orbit is the first classical test for this theory. Here, the precession predictions of Newtonian effects have been challenged by Mercury deviation. Here, the word perihelion directly refers to the central body of our solar system. The observed amount of perihelion shift agrees closely within this tests which was put forwarded by Einstein.
The second classical test is the deflection of light by the Sun and this first came in to focus in 1784 with Henry Cavendish and with and Johann Georg von Soldner in 1801. The change in position of stars was noted in this test where it is observed that how stars passed nearby the Sun on celestial sphere and the light deflection was tested for the first time.
In the year 1907, Einstein predicted the gravitational redshift of light as the third classical test of general relativity. But, it was really difficult to prove this test. However, in 1925, it was measured by Walter Sydney Adams. But, the result was completely successful and was excellent in the year 1959 when tested from Harvard University’s Jefferson tower and is known as the Pound–Rebka experiment.
Cosmological tests are significant tests of general relativity in modern days’ environment. These tests are done in largest scales. The discovery of universe and expansion of universe are closely related with this test. The famous Big Bang observer tests are also related with this test of general relativity. With this test, non-stationary solutions are found Einstein’s equations and he himself agreed with this.
Recently, a number of gravitational wave detectors have been built for present day test like direct detection of gravitational waves. Here, various astronomical events are observed like merging of two neutron stars by directly detecting the gravitational waves through detectors.