Successful Predictions of General Relativity

General relativity says that the laws of special relativity are approximately correct whenever the effects of gravity are negligible. So, all of the strange consequences of special relativity—the time dilation and length contraction that occurs with objects moving at high speeds, for instance—are also predicted by general relativity. But general relativity adds some surprising new predictions that no previous theory can explain:

In addition to these successful new predictions, Einstein’s general theory of relativity finally solved an old puzzle about the orbits of planets around the sun. Newton had explained why the planetary orbits are approximately elliptical, as mentioned in chapter 2. However, it turns out that the ellipse itself precesses (rotates), as shown in the animation below. This phenomenon, called orbital precession, was first detected with the planet mercury in 1859; later observations revealed that other planets (and also moons, comets, etc.) precess in a similar way. Orbital precession could not be adequately explained by Newton’s laws, but was explained by general relativity.

animation illustrating orbital precession
Orbital Precession

Credit: WillowW, (CC BY 3.0) via Wikimedia Commons