General relativity has changed our understanding of space and time. ...The spacetime of general relativity ...is likely to be just a classical approximation that loses its meaning in the quantum theory, for the same reason the trajectory of a particle does.
Carlo RovelliRelated topics
approximation classical general likely meaning quantum reason relativity space trajectory understanding spacetimeRelated quotes
The development during the present century is characterized by two theoretical systems essentially independent of each other: the theory of relativity and the quantum theory. The two systems do not directly contradict each other; but they seem little adapted to fusion into one unified theory.
Albert Einstein