• How to Delay Death and Look Further Into the Future if You Fall Into a Black Hole

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    • Keywords


      General relativity, black holes, Lemaitre frame, free fall.

    • Abstract


      In this note, we present a pedagogical illustration of peculiar properties of motion in the vicinity of and inside black holes. We discuss how a momentary impulse can modify the life­time of an object radially falling into a Schwarzschild black hole down to singularity. The well-known upper limit for a proper time spent within a horizon, in fact, requires an in­finitely powerful kick. We calculate the proper time interval (perceived as the personal lifetime of a falling observer) till the contact with the singularity, as well as the time interval in the Lemaitre frame (which reflects how far into the future of the outer world a falling observer can look), for different values of the kick received by the falling body. We discuss the ideal strategy to increase both time intervals by an engine with a finite power. This example is suitable for university seminars for undergraduate students specializing in general relativity and related astrophysical subjects.

    • Author Affiliations


      Alexei Toporensky1 Sergei Popov1

      1. Sternberg Astronomical Institute Universitetski pr. 13 Moscow, 119234, Russia
    • Dates


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