From the start, the General Theory of Relativity is confronted with a series of expectations about a new theory of gravity. Even more important is the need for an affirmation of the predictions of the theory, something Einstein has been working on since 1911, long before the concept’s final formulation. Einstein’s efforts to convince German astronomers of the important challenges these questions pose are, for the most part, fruitless. Not until 1919 does an English expedition, led by Eddington, find the breakthrough. It confirms the deflection of light in a gravitational field.

Today, Einstein's General Relativity is the basis of cosmology. It explains the expansion of the universe and makes it possible to describe strange phenomena, like black holes, gravitational lenses and gravitational waves. All that is completely unknown when the theory is formulated. Step by step, the cosmological problem transforms from a philosophical question into a one that can only be decided by means of astronomical observation.