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arXiv:2104.01191gr-qc

The Edges of Our Universe

Toby Ord

Early discovery. Linked by one identifiable commenter. This paper is outside the main ranking; a mention is not an endorsement.

Abstract

This paper explores the fundamental causal limits on how much of the universe we can observe or affect. It distinguishes four principal regions: the affectable universe, the observable universe, the eventually observable universe, and the ultimately observable universe. It then shows how these (and other) causal limits set physical bounds on what spacefaring civilisations could achieve over the longterm future.

arXiv comments
45 pages, 16 figures
Journal reference
DOI
Subjects
gr-qcGeneral Relativity and Quantum Cosmology hep-thHigh Energy Physics, Theory physics.hist-phHistory and Philosophy of Physics

On Hacker News

Linked by 1 identifiable commenter in 1 comment across 1 thread, from Jan 2022 to Jan 2022. Found in 3 HN submissions from Apr 2021 to Aug 2022. Open submission discussions.

Comments linking this paper, per year.

Discussed in comments1 thread

  1. Disambiguating the ‘Observable Universe’ 1 comment

    • Someone linked it in the comments over there, but I think it's worth reposting here, "The Edges of Our Universe" by Toby Ord (https://arxiv.org/abs/2104.01191), which goes over a number of different radii of this form that one could define.

      SniffnoyView on HNParent context

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