Final answer:
Einstein's General Theory of Relativity unified our understanding of gravity as a curvature of spacetime, providing a new perspective on both accelerated motion and the impact of mass on the fabric of the universe which has been supported by experimental verification.
Step-by-step explanation:
The great unification represented in Einstein's General Theory of Relativity can be described as the fundamental insight into gravity being a manifestation of mass warping space and time. By expanding upon Special Relativity, general relativity explains not only motion without acceleration but also accelerated motion within a gravitational context. The Principle of Equivalence, a cornerstone of this theory, suggests that a person in free fall does not feel their own weight, leading to the revolutionary conclusion that gravity is intrinsically related to the curvature of spacetime. The predictions of general relativity, such as the bending of light by gravity, have been experimentally verified, notably during a solar eclipse in 1919, and have since become fundamental to our understanding of astronomical phenomena like black holes and the unification of forces potentially achieved through a unified quantum gravity theory, a Theory of Everything (TOE).