In accordance with Mach’s critique of Newton, Einstein has doubts about the concept of absolute space that leads to the privileged treatment of certain coordinate systems in classical physics. Only in these inertial systems do the physical laws always take on the same form. Einstein, however, demands general covariance, that is: the natural laws must be completely independent of the choice of coordinate system.

The Entwurf Theory is not generally covariant. Einstein accepts this reluctantly and finds an explanation, which he later realizes to be untenable. Another argument against the theory is the value calculated for the perihelion motion of the planet Mercury. It does not correspond with observations.

In fall 1915, Einstein thus returns to a generally covariant theory and, after several changes, publishes the General Theory of Relativity as we know it today. Immediately, Karl Schwarzschild manages to exactly calculate the gravitational field of the sun with this theory.

David Hilbert picks up on Einstein’s results in the fall of 1915 as well, and formulates on this basis his own theory of gravitation and electromagnetism.