Science Park "Albert Einstein" Potsdam

Stefan and I, we were in Potsdam the past few days where I was visiting the Albert-Einstein Institute in Golm. While in the area, we also stopped at the "Science Park" in Potsdam. Potsdam may be more famous for the parks of Sanssouci and other palaces of the Prussian kings but this park, on a hill not far off the city center, is definitly worth a visit when you are interested in the history of science.

The park has an interesting past: Named "Telegraphenberg" (Telegraph Hill), it originally was the location of a relais station of an optical telegraph system linking Berlin to the Rhine. The park was designed in the second half of the 19th century, when an Astrophysical Observatory and a Geodetic Institute were installed on the hill.


The park on Telegraph Hill, Potsdam.
It was here that in 1880, Albert Michelson made his first interference experiment to test the direction-dependence of the speed of light. He was a guest scientist at the physics institute of Hermann von Helmholtz in Berlin at the time, and had to move his sensitive experimental setup to quiet Potsdam to escape the noise and vibrations of street traffic in the capital. Of course, Michelson didn't find any signs of the expected ether drift at the time, and thought of his experiment as a failure. Back to the US, he convinced his colleague Morley to collaborate on an improved experimental setup, and the rest is history.


The "Michelson Building" on Telegraph Hill, Potsdam.
The building where Michelson had installed his interferometer in the basement is now called the "Michelson Building", and accommodates the Potsdam Institute for Climate Impact Research.

The most famous monument on Telegraph Hill in Potsdam is the "Einstein Tower," housing a solar telescope. Designed by expressionist architect Erich Mendelson and financed in parts by Carl Bosch (the same Bosch who built the "Villa Bosch" in Heidelberg I visited last year), it is a cute looking phallus symbol whose scientific purpose was to test the redshift of spectral lines of sunlight in the Sun's gravitational field, one of the predictions of Einstein's theory of General Relativity.


The "Einstein Tower" solar observatory on Telegraph Hill, Potsdam.
Also this experiment failed, due to the thermal broadening of spectral lines and the fluctuations of the Sun's surface which, by the Doppler shift, mask the gravitational redshift and form a source of systematic error much higher than originally expected. Evidence for the "Gravitational Displacement of Lines in the Solar Spectrum" eventually came from other observatories, and unambiguous proof of the gravitational redshift finally was provided by the experiments of Rebka and Pound in 1959, using the Mössbauer effect to detect tiny shifts in the gamma ray frequencies of iron nuclei.

Nevertheless, the Einstein Tower is the only observatory on Telegraph Hill still in use for active research: The solar telescope and spectrographs now serve to study magnetic fields in the Sun's photosphere.


The building is quite small. A person in the scene, in this photo Stefan, helps to set a scale.

Directly in front of the Einstein-Tower, I found, to my surprise, a Boltzmann brain popping out of the ground:



Wikipedia informed us later that the bronze brain with the imprint "3 SEC" was put in place by the artist Volker März in 2002. It is titled "The 3 SEC Bronze Brain – Admonition to the Now – Monument to the continuous present” and symbolizes the scientific thesis that “the experience of continuity is based on an illusion" and that "continuity arises through the networking of contents, which in each case are represented in a time window of three seconds."

I wonder what Einstein would have thought of that.