Forever Is a Day: Supertasks in Pitowsky and Malament-Hogarth Spacetimes

  title={Forever Is a Day: Supertasks in Pitowsky and Malament-Hogarth Spacetimes},
  author={John Earman and John D. Norton},
  journal={Philosophy of Science},
  pages={22 - 42}
The standard theory of computation excludes computations whose completion requires an infinite number of steps. Malament-Hogarth spacetimes admit observers whose pasts contain entire future-directed, timelike half-curves of infinite proper length. We investigate the physical properties of these spacetimes and ask whether they and other spacetimes allow the observer to know the outcome of a computation with infinitely many steps. 

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