Holiday in a black hole

Institute for Theoretical Physics - Science Park 904, PO Box 94485, 1090 GL Amsterdam, The Netherlands

Received: 22 September 2025
Accepted: 2 February 2026

Abstract

A “blackholonaut” making a tour through a black hole can go out by using his engines; when the black hole is charged, this typically occurs automatically. The tour takes a finite proper time. For an ingoing Painlevé-Gullstrand observer, the ingoing part also lasts a finite time; for an outgoing one, the outgoing part does so. These observers outside the black hole can communicate with each other and with a stationary observer. For the latter, the tour also lasts a finite time, even though signals emitted during the entrance to the black hole will reach him forever. On his clock, the blackholonaut comes out of the black hole in the infinte past. Cross-horizon communication with the blackholonaut is possible. Closed time-like curves occur for a stationary observer, but not for a pair of moving observers. If crossing points occur, they are peculiarities in the mathematical description by the observer, which do not relate to physical events.