A brief observational history of the black-hole spacetimes (Q277759)

This paper celebrates the 100th anniversary of the detection of the Schwarzschild solution to General Relativity in 1915/1916. That solution became later the geometric foundation for the physics of black holes. The present paper classifies those astronomically observed objects, which have the status of a ``black hole candidate''. To each of these candidates, Kundt mentions physically sensible possibilities to explain the observations also without the existence of a black hole. The final section of this paper has the headline: Should cosmic censorship be replaced by AUC, the avoidance of unhalted collapse?