Quite a while ago I wrote about how a beam of light is bent by a gravitational field, a process known as gravitational lensing. The effect was famously first observed by Eddington in the early 1900s, and was one of the three great “tests” of general relativity.
When we say gravity is a curvature of space, what does that really mean? It all has to do with the fact that the laws of physics are the same from any vantage point.
Frame dragging is one of those strange effects that occurs in general relativity. It happens when a rotating mass twists space. Strange as it is, we’ve observed the effect near Earth.
The equivalence principle states that everything falls at the same rate in a gravitational field. But what about antimatter? We think it would fall just like regular matter, but we haven’t yet been able to put that assumption to the test.