Editorial

Abstract

The first discovery of gravitational waves in September 2015 has spectacularly exhibited the merging of two black holes, each of about 30 solar masses. For this discovery, which was a fantastic confirmation of Einstein's prediction of gravitational waves, the three physicists Barry Barish, Kip Thorne and Rainer Weiss were honored by the Physics Nobel Prize of the year 2017. However, black holes are still very mysterious objects, both seen from theoretical, fundamental physics and concerning their role in astrophysics and the evolution of the Universe. There are several key questions: What is the quantum nature of black holes? In particular, can one derive, possibly based on the holographic principle, a quantum description of black holes that provides a clue to the black hole information puzzle? Can newly discussed classical BMS-like symmetries, related to soft graviton emission, help to shed more light on Hawking radiation and the black hole entropy. Can astrophysical measurements reveal deviations from general relativity that hint at quantum effects? Can primordial black holes serve as viable dark matter candidates? We expect that the field of gravitational waves, black holes and their interrelation to quantum information will further evolve during the next years and will give further new insights into the quantum nature of black holes. We wish all authors and readers of “Fortschritte der Physik” a happy and successful new year 2018. Dieter Lüst (Editor) Wolfgang P. Schleich (Co-Editor)