Journal Article

Cosmological radar ranging in an expanding universe*

Geraint F. Lewis, Matthew J. Francis, Luke A. Barnes, Juliana Kwan and J. Berian James

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 388, issue 3, pages 960-964
Published in print August 2008 | ISSN: 0035-8711
Published online July 2008 | e-ISSN: 1365-2966 | DOI:
Cosmological radar ranging in an expanding universe*

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While modern cosmology, founded in the language of general relativity, is almost a century old, the meaning of the expansion of space is still being debated. In this paper, the question of radar ranging in an expanding universe is examined, focusing upon light travel times during the ranging; it has recently been claimed that this proves that space physically expands. We generalize the problem into considering the return journey of an accelerating rocketeer, showing that while this agrees with expectations of special relativity for an empty universe, distinct differences occur when the universe contains matter. We conclude that this does not require the expansion of space to be a physical phenomenon, rather that we cannot neglect the influence of matter, seen through the laws of general relativity, when considering motions on cosmic scales.

Keywords: cosmology: theory

Journal Article.  3595 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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