The reason for our shared trip was a very special one: my son had qualified for the finals of the Geo-Olympiade in Potsdam. The event was spread over two days. On the second day, at the end of the event, I picked him up at the Albert Einstein Science Park on the Telegrafenberg.
From the outset we had planned to take a look at the extensive grounds together once the event was over.
We had deliberately not informed ourselves about possible guided tours. We just wanted to see the grounds, take pictures and spend time together. Under brilliant sunshine and pleasantly warm temperatures we wandered roughly two kilometres across the grounds in about an hour and a half, taking our time. The site has a small, signposted trail with around ten stations, each offering a short description of the history and function of the historic buildings and measurement stations. This park is a piece of open-air scientific history.
The Telegrafenberg itself is a place where, over the past 150 years or so, world-class research has been carried out – on the sun, the stars, the earth, the climate. Interstellar matter was first proven here, evidence for Einstein’s theory of relativity was sought here, and the world’s first remote recording of an earthquake took place here. Today the area is home to institutions including the Leibniz Institute for Astrophysics Potsdam (AIP) and the Potsdam Institute for Climate Impact Research (PIK). For us, three buildings were the undisputed highlights of the walk
Michelson House – the world’s first astrophysical observatory
The first sight of the Michelson House is striking: a long, red-and-yellow striped brick building with several domes against a deep blue sky. A panel told us that this was the world’s first astrophysical observatory, completed in 1879. It is famous above all for one of its directors, the astronomer and physicist Karl Schwarzschild, who in 1916 found the first known exact solution of Einstein’s field equations. The building owes its modern name to Albert A. Michelson, who in 1881 carried out his first interferometer experiment in the basement here – an experiment that would profoundly shape the physics of the twentieth century. In the same place, Ernst Rebeur-Paschwitz achieved the world’s first remote recording of an earthquake in 1889. Since 2001 the building has housed the Potsdam Institute for Climate Impact Research.
Great Refractor – a giant from imperial times
We continued on to the Great Refractor – the structure is simply impressive: a massive brick body crowned by a 200-tonne rotatable dome twenty-one metres in diameter. The telescope was inaugurated in 1899 in the presence of the Kaiser and is to this day the fourth-largest lens telescope in the world. Inside sits a double refractor with two telescopes on a single mount; the larger objective measures 80 centimetres in diameter with a focal length of more than twelve metres. In 1904, Johannes Hartmann used this telescope to discover interstellar matter, concluding from the spectra of binary stars that the space between the stars is not empty but filled with gas and dust. After war damage in 1945, modernisation in 1953 and the eventual cessation of operations in 1968, the story of the refractor could have ended there. That the telescope stands fully functional in its dome again today is thanks to the Förderverein Großer Refraktor Potsdam, founded in 1997, and to many generous donations; it was re-inaugurated in 2006. We mostly enjoyed the building from the outside – the combination of brick and metal dome was a treat
Einstein Tower – architecture and physics in pure form
The high point of our walk was, for both of us, the Einstein Tower. The tower was built between 1919 and 1924 as the first significant work of the architect Erich Mendelsohn, in close collaboration with Albert Einstein and the astronomer Erwin Finlay Freundlich. The original goal was to detect the gravitational redshift of spectral lines in the sun’s gravitational field, as predicted by Einstein’s theory of relativity. Because solar convection produces a blueshift of comparable magnitude, however, experimental confirmation only came much later. Until the Second World War, the Einstein Tower was the most scientifically important solar telescope in Europe; after a comprehensive renovation in 1999 it is still used today by the AIP, mainly for testing instruments that are later deployed on modern solar telescopes on Tenerife. My son and I walked around the tower a few times, simply to see this unusual shape from different angles. The visit would have been worthwhile for this view alone.
Conclusion
After a good hour and a half, two kilometres and a fair number of photographs, we agreed: even without a guided tour, the Albert Einstein Science Park is well worth a visit. You can explore the park at your own pace, the station panels provide enough context, and the architecture tells stories that go far beyond what is visible. For my son it was a fitting end to an exciting event – for me, a quiet highlight I will be thinking about for a long time to come.