Einstein Tower

from Wikipedia, the free encyclopedia

The Einstein Tower is an observatory built between 1920 and 1922 in the " Albert Einstein Science Park " on Telegrafenberg in Potsdam , a building by the architect Erich Mendelsohn that was revolutionary for its time of construction . It was named after the 1921 Nobel Prize winner in physics . Here the validity of Einstein's theory of relativity should be confirmed experimentally. The building is a listed building . The host and operator of the tower telescope is the Leibniz Institute for Astrophysics Potsdam .

The Einstein Tower

The construction of the tower

Idea and implementation

Model of the Einstein Tower
Plaque by the Einstein Tower

While Einstein was working on his general theory of relativity from 1911 to 1915 , he challenged the astronomical community to test his predictions experimentally. Erwin Finlay Freundlich was one of the first scientists to pursue the new problem; he was an astrophysicist at the observatory in Babelsberg near Potsdam and had known Einstein since 1911. Since 1917 he has been planning an observatory in coordination with Einstein, which had to be suitable for the special requirements.

Freundlich maintained close personal contacts with the architect Erich Mendelsohn . He taught him extensively on the development of general relativity and interested him in the design of the observatory. At that time, Mendelsohn was looking for new architectural forms of expression that he wanted to realize with the contemporary building materials of steel and reinforced concrete . He wrote about these building materials that “if recognized in their elastic potential, they necessarily lead to an architecture that is completely different from everything we knew before” .

As a soldier in World War I , he had already developed ideas for the new architecture in numerous small-format sketches of fictional buildings . Now the possibility of realizing his ideas became apparent. Of course, Mendelsohn had to follow the guidelines that Freundlich defined according to scientific requirements. The planned vertical telescope was to be installed on its own foundation independently of the rest of the building inside, the actual building primarily served as a protective cover.

This resulted in unusual creative freedom for the architect, which he used for his construction. The first concrete drafts were made in 1919, construction took place until 1922, the tedious installation of the scientific equipment was not completed until 1924. The architect Richard Neutra , who was employed by Mendelsohn at the time, designed the area around the tower. The building is usually referred to as an outstanding example of expressionist architecture . But there are also distant echoes of Art Nouveau . Einstein summed up his impressions with the word: “ Organic! “Together, an assessment with which Mendelsohn was absolutely in agreement (compare also organic architecture ). The architect himself wrote: “ For the first time I am transferring function and dynamics as a pair of opposites to the field of architecture. I owe this scientific reflection to my frequent presence in discussions between Einstein and his colleagues ”. Harald von Klüber, an employee at the Einstein Tower, explained the unusual new shapes by saying that Mendelsohn's style reflected the aspects of modern technology , mathematics and physics and responded to their complex, but also aesthetic ideas with complex, swaying shapes and elegantly curved curves.

Thanks to Einstein's worldwide popularity, his position as a member of the Prussian Academy of Sciences and as director of the Kaiser Wilhelm Institute for Physics , the project of a "tower telescope of the Einstein Foundation " was decisively promoted. Despite the difficult economic conditions in the immediate post-war period, the project was financed, half by the Prussian state and half by the "Albert Einstein Foundation" of German industry. On December 6, 1924 , the institute officially started operations. Einstein himself led the first meeting of the board of trustees in the work room of the observatory. In the same year the name "Einstein Tower" became common.

Structural problems

First renovations in 1927/28

The Einstein Tower was designed as a reinforced concrete structure. He was regarded as such from the beginning and was also referred to in the specialist literature. Mendelsohn never contradicted this account, even though it literally contained only half the truth. Building with concrete was not a fully developed technique at that time. The quality of the material left a lot to be desired, its processing - for example the formwork of unusual shapes - was not sufficiently tested. Mendelsohn therefore had to have the observatory built using a mixed construction method. The dome , the outer walls of the extensions, the terrace and the terrace stairs are made of concrete . The center of the complex, the tower itself, is made of brickwork , as are the roofs over the extensions. The desired impression of a homogeneous concrete structure only emerged after everything had been covered with an even layer of fine-grain, light ocher-colored spray plaster .

With the initial difficulties began a long history of damage and repairs. The main causes were thermal stresses due to different materials and wall thicknesses as well as the strict north-south orientation of the observatory. As early as 1927, only five years after completion, numerous defects - moisture penetration, cracks and rust damage  - had to be extensively renovated . Sheets were attached in several places, which significantly changed the appearance. But these protective measures also ultimately damaged the building fabric. In 1937, fungal infestation made it necessary to expand the large prism spectrograph . The second general overhaul was necessary in 1940/41. In 1945, during World War II , an aerial mine exploded nearby and destroyed various parts of the building. After the restoration in 1950, further repairs were carried out in 1958, 1964, 1974–1978 and 1984.

At the beginning of the 1990s, the existence of the building seemed threatened. Extensive investigations and mapping of the damaged areas were followed by the most thorough renovation to date between 1997 and 1999. Care was taken to preserve as much of the original substance as possible. The joint sponsors of the measures, which cost around three million euros, were a private foundation, which took on two thirds of the costs, and the Leibniz Institute for Astrophysics Potsdam as the host of the Einstein Tower. In the future, the critical areas of the system will be regularly monitored and serviced using a maintenance plan.

Research

Device and subject

In 1911 Einstein published a preliminary version of his general theory of relativity, a novel theory of gravity . One of the predicted effects in this context was the redshift of light, a slight shift in spectral lines in the sun's gravitational field. The solar observatory in Babelsberg was conceived and built primarily to examine this phenomenon.

The model for the facility designed by Freundlich was the Mount Wilson Observatory in California , the world's first tower telescope. With tower telescopes, a coelostat - a system of two deflecting mirrors - at the top of a vertical construction directs the light down onto the lens . The actual lens system is rigidly integrated into the construction, the mirrors at its head end are movable; only these smaller, lighter parts of the instrument have to follow the path of the sun. Due to the vertical arrangement, air turbulence near the ground can hardly have a disruptive effect.

In the Einstein Tower, the construction to accommodate the optics consists of two wooden scaffolds, each six meters high, one above the other, with black panels attached at certain intervals . The telescope has a lens with a diameter of 60 cm and a focal length of 14 m. Rooms for observation and measurements are located at the base of the tower. In California the laboratories were one below the other, in Babelsberg they were arranged horizontally. Another swiveling mirror guides the sunlight into the spectrographic room, which is located in the basement behind an earth wall on the south side of the tower, is around 14 m long and thermally insulated - there the light is broken down into its spectral components and analyzed. The elongated shape of the entire facility resulted from the concept of the horizontal laboratory wing.

Shortly after the research work began, it became clear that the evidence sought was much more difficult to provide than initially expected. The minimal shifts of the spectral lines were overlaid by other solar influences. The reason was the atmospheric turbulence on the sun's surface. From the very beginning, Einstein and Freundlich did not only have the special problem of redshift in mind, but also thought of basic research in solar physics. The laboratories were designed so that new equipment could be installed without any problems. The turbulent behavior of the outer solar atmosphere soon became the main subject of research at the Einstein Tower. The effect of the redshift could only be demonstrated here in the 1950s, after it was possible to analyze the complex disturbances of the solar atmosphere more precisely.

Todays situation

The properties and behavior of magnetic fields provide the key to understanding solar activities. These problems are the focus of work in the Einstein Tower. With the help of a double spectrograph and two photoelectric polarization analyzers , magnetic fields on the sun are measured. The measurements in the photosphere , the area of ​​visible light, allow conclusions to be drawn about the course in higher layers.

The Potsdam astronomers are involved in the operation of an observatory on Tenerife . Instruments that will later be used there are developed and tested at the Einstein Tower. The Einstein Tower is also of great importance for the education of students.

Art objects

The Einstein sculpture

In the entrance area of ​​the tower, a bronze bust of Einstein is shown today , which originally stood in the study of the observatory. In 1933, right after the start of the anti-Semitic dictatorship of the National Socialists , the Einstein Tower lost its name (renamed “Institute for Solar Physics”) and its status as an independent institute, images of Einstein were removed and sculptures were to be melted down. After 1945 it became clear that employees had rescued the portrait bust , which can now be seen below in the tower, and kept it behind boxes in the spectographers' room.

The 3sec bronze brain

A few meters before the stairs to the Einstein Tower you can find an art object about the size of a fist in the pavement of the forecourt - the bronze, greatly reduced rendering of the human brain , which has now been gleaming with wear and tear and embossed with four characters: 3SEC. It is a work by the Berlin artist Volker März , which he placed here in 2002 (and in an identical form in front of the Neurological Institute of the Charité in Berlin). The small sculpture refers to a scientific thesis by Ernst Pöppel , according to which “ the experience of continuity is based on an illusion. Continuity comes about through the networking of the contents, which are each represented in a three-second time window. We reconstruct the temporal continuity based on what is represented in the individual islands of consciousness ”. Following this thought, März describes his work as "The 3 sec bronze brain - memorial of the present - memorial of the incessant present."

literature

  • Norbert Huse (Ed.): Mendelsohn. The Einstein Tower. Stuttgart 2000, ISBN 3-7828-1512-2 .
  • Joachim Krausse, Dietmar Ropohl, Walter Scheiffele: From the Great Refractor to the Einstein Tower. 2002, ISBN 3-936383-01-4 .
  • Klaus Hentschel : The Einstein Tower. Erwin F. Freundlich and the theory of relativity - approaches to a “dense description” of institutional, biographical and theoretical-historical aspects. Spectrum, Heidelberg 1992, ISBN 3-86025-025-6 .
  • Hans Wilderotter (Ed.): A tower for Albert Einstein. Potsdam, the light and the exploration of the sky. Book accompanying the exhibition, Potsdam 2005, ISBN 3-9809266-1-3

Individual evidence

  1. ^ The Einstein Tower

Web links

Commons : Einstein Tower  - Collection of Images

Coordinates: 52 ° 22 ′ 44 ″  N , 13 ° 3 ′ 49 ″  E