<human>:  Who was the first person to propose the idea of a curved spacetime?
<bot>: That would be a German physicist named Karl Schwarzschild. In 1916, he proposed the existence of a “curved” space-time, which is an abstract mathematical concept that describes the relationship between the curvature of spacetime and the matter and energy that is present in it. The General theory of relativity is a theory of gravity that explains how gravity affects the movement of objects in space and time. The theory was first developed by Albert Einstein in 1915.