Space Time curvature

Curve Curve is just like the layer of the earth surface. The earth atmosphere curvature is lesser curvature than the ocean curvature and the floor of ocean is the greater curvature than the ocean.

Geodesics

Why space time curvature caused? It is simply to say geodesics. When a massive objects fly so past then it follows geodesic path. Geodesics path will be curvature geodesics, ignoring straight line geodesics  of Eucleodian geometry if there have no attraction force else.

In general theory of relativity, gravity is defined as a curvature of four dimensional space-time. But in quantum field theory, space-time curvature is ignored by saying that there have no any curve. In quantum field theory space is four dimensional.

The authenticity of space-time curvature is found in Reimennian geometry that says space is four dimensional.