We live in a world where we're able to move around and we kind of can get this field that there are three dimensions in which we can move. So, what we actually have to do is think of space and time as being one object. And to move from thinking about them as just one object, this object also has a shape. This is when Einstein added general relativity to tell us about what that shape is. There's this relationship between the shape of quote-unquote spacetime, this fabric that we all live in,. The way that spacetime is shaped tells matter how to move throughout spacetime, what paths it should take. It was first tested using solar eclipses.