We met Cliff Will
on a warm summer day at the former Astrophysical Observatory Potsdam, which is in a science park on a hill in Potsdam called the Telegraphenberg.
As Cliff explains to Annalie in the film, the man who found the first solution of Einstein's equations was Karl Schwarzschild, who was the director of the observatory at the time (1916). The Schwarzschild Solution is now understood to describe a black hole.
Annalie and Cliff later continued their conversation in the atrium of the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI), about 7 km away, which is the largest research institute in the world specializing in the study of general relativity in all its modern applications.
Schwarzschild's building has played an important role in science for over a century, from long before Schwarzschild moved into it up to the present time. Today it houses the Potsdam Institute for Climate Impact Research, one of the leading institutes in the world for the study of global warming. (The Potsdam Observatory itself is located a few kilometers away and is now called the Astrophysical Institute of Potsdam.) But its history before Schwarzschild is also closely connected to relativity.
Schwarzschild's building is today called Michelson House, because it is where the American physicist Albert Michelson first performed his famous experiment on light that eventually proved to be the first piece of evidence for special relativity. Michelson worked here in 1881, when Einstein himself was only 2 years old! The experiment is normally known as the Michelson-Morley Experiment because Michelson repeated it, with his collaborator Edward Morley, in 1887 with greater precision to be sure of the result.
Michelson won the Nobel Prize for Physics for this work in 1907. To do his experiment, Michelson invented a precision measuring instrument called the interferometer, which is now widely used in science and engineering, and which is the basis for modern gravitational wave detectors. So the location for Annalie's interview with Cliff Will is one of the most important buildings in the whole history of science. Incidentally, Michelson did his experiment in the very quiet, low-vibration basement of the central round tower just behind Annalie in the opening sequence of our film.
Near Michelson House on the Telegraphenberg is another important scientific landmark, the Einstein Tower. This is a solar observatory built in the 1920's to test some of Einstein's predictions from general relativity. Annalie used it as a location when she interviewed the young German physicist Christian Ott, who uses supercomputers and general relativity to investigate what happens when stars explode as supernovas.
Ott did his work for his PhD at the AEI. The interview with Ott will be released shortly.
The Telegraphenberg is near a river called the Havel, and just down the river is another scientific location Annalie used for two further interviews: Caputh, a small village where Einstein built his summer house. At Einstein's house Annalie interviewed the historian of science Jürgen Renn, who explained why Einstein himself did not accept that black holes could be real. In a restaurant on the Havel in Caputh Annalie interviewed the young Indian physicist Badri Krishnan about how sophisticated computer programs are "listening" for gravitational waves from black holes. The interviews with Renn and Krishnan will be released shortly.