Un lugar entre la tierra y las estrellas. Luces y sombras en la Torre Einstein

The Einstein Tower was built in 1921 at the Telegraphsberg in Potsdam with an unique purpose: the empirical demonstration (or refutation) of the basis for the Theory of Relativity by Albert Einstein. Established already from its origen as a monument that time has consolidated as the icon of an emerging Modernity, the Einstein Tower is at the same time the story of a triple failure: Its explicit objective was never met (concluding results were never arrived at), its location was inadequate (the main observatory was transferred afterwards; first to Lucerne, and later to the Teide mountain), and, on the personal and architectural side, it proved a point of inflection for the career of Erich Mendelsohn, even though it gave him fame and recognition. This article describes this first project not so much as the start of a professional career, but rather as the necessary closure to a path initiated with his war drawings. A building almost entirely devoid of openings which springs up from the ground in order to follow the trajectory of an object 150 million kilometers away with its only eye. A scientific program, where human presence is reduced to a minimum (even today) in order to protect the sofisticated equipment. The Einstein Tower is above all a fixed telescope mounted on a building. Its biggest contribution, a horizontal spectrographic laboratory halfburied beneath the main vertical support of the tower, is due to its promoter, Professor Erwin Finlay- Freundlich. This astrophysicist knew how to orchestrate an entire media campaign associated to the recent prestige of Albert Einstein, who never worked in the tower (but who did not hesitate to have a picture taken next to it). Initially conceived as a mere technical container, the young Mendelsohn soon established that the project for the Einstein Tower, limited in practice to the design of an outer covering shell the interior (there was strongly conditioned to the requirements set by engineers from Carl-Zeiss), should go further and to express its architecture, the theory that tried to demonstrate in the inside. The mass-energy equivalence formulated by Einstein was translated architecturally into a game of mass and light, a balance of movement, in the words of the young architect. Rather than expressing it, the tower "represented" movement, reproducing an instant frozen in time. Luise Mendelsohn referred to the works she often visited as the "construction of a ship", and in her dreams she saw it slip away navigating down the hill. Nautical references are not alien to this project: more than a ship, the Eins