Petra Görlich, Antje Horn-Conrad, Heike Kampe, Matthias Zimmermann, Jana Scholz, Silke Engel, Simon Schneider

• Speaking of the cosmos means speaking about nothing less than everything, about the entirety of space filled with matter and energy. We only see a tiny fraction of it from Earth: planets like Venus or stars like the Sun. There are at least 100 billion stars in our home galaxy alone. Bound by gravity, these luminescent celestial bodies of very hot gas form a system visible from Earth as a whitish ribbon, which we call the Milky Way. The observable cosmos contains at least 100 billion such galaxies with stars, cosmic dust, gas, and probably dark matter as well. The universe is 13.8 billion years old; crossing it once would probably take 78 billion light-years. Given these dimensions, it is hardly surprising that for us humans, the mystery of the properties of the cosmos is connected with questions of being. Where do we come from? Where are we going? Are we alone in the universe? Such questions are in the wheelhouse of astrophysicists, who explore the vastness of the cosmos through physical means, even though they, of course, deal withSpeaking of the cosmos means speaking about nothing less than everything, about the entirety of space filled with matter and energy. We only see a tiny fraction of it from Earth: planets like Venus or stars like the Sun. There are at least 100 billion stars in our home galaxy alone. Bound by gravity, these luminescent celestial bodies of very hot gas form a system visible from Earth as a whitish ribbon, which we call the Milky Way. The observable cosmos contains at least 100 billion such galaxies with stars, cosmic dust, gas, and probably dark matter as well. The universe is 13.8 billion years old; crossing it once would probably take 78 billion light-years. Given these dimensions, it is hardly surprising that for us humans, the mystery of the properties of the cosmos is connected with questions of being. Where do we come from? Where are we going? Are we alone in the universe? Such questions are in the wheelhouse of astrophysicists, who explore the vastness of the cosmos through physical means, even though they, of course, deal with physical laws, mathematical formulas, and complicated measuring methods. In this issue of Portal Wissen, we talked with astrophysicists at the University of Potsdam about their research and everyday work. Lutz Wisotzki showed us a 3D spectrograph, which he has developed in collaboration with colleagues from the Leibniz Institute for Astrophysics (AIP) and six other European institutes. This technical masterpiece enables scientists to look deeply into space and to “journey” through time to galaxies shortly after the Big Bang. Philipp Richter introduced us to the astrophysics research initiative and demonstrated how the University of Potsdam is working together with the AIP, the Albert Einstein Institute (AEI) and the Deutsches Elektronen-Synchrotron (DESY) to train junior researchers. The newly appointed Professor of Stellar Astrophysics, Stephan Geier, presented us with stars so close together to each other that they appear to be one to the naked eye. The physicist, who is also a historian, researches their turbulent relationships. We have not confined ourselves to cosmic themes, though, but also questioned rather earthly matters such as modern consumption. We have thought about potential love relationships with robots and testimonials in literature and art. We learned why the rainforest in Central Africa disappeared 2,600 years ago, how to produce knee prostheses on a production line, and how animals in the field benefit from big data. But back to the cosmos. The writing of late astrophysicist Stephen Hawking fundamentally shaped our concepts and knowledge of the universe. And that is because he was both an important physicist and a literary genius. Hardly anyone has been able to capture difficult facts in such a clear, understandable, and beautiful language. With this exemplary understanding of science in mind, we hope to offer you a stimulating read. The Editors…