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Posted by: ljk4-1 Nov 9 2005, 04:20 PM

Astrophysics, abstract
astro-ph/0509268

From: Jeremy S. Heyl [view email]
Date (v1): Fri, 9 Sep 2005 21:49:22 GMT (18kb)
Date (revised v2): Tue, 8 Nov 2005 05:13:13 GMT (18kb)

The Long-Term Future of Space Travel

Authors: Jeremy S. Heyl

Comments: 5 pages, 3 figures, minor changes to reflect version accepted to PRD

The fact that we apparently live in an accelerating universe places limitations on where humans might visit. If the current energy density of the universe is dominated by a cosmological constant, a rocket could reach a galaxy observed today at a redshift of 1.7 on a one-way journey or merely 0.65 on a round trip. Unfortunately these maximal trips are impractical as they require an infinite proper time to traverse. However, calculating the rocket trajectory in detail shows that a rocketeer could nearly reach such galaxies within a lifetime (a long lifetime admittedly -- about 100 years). For less negative values of $w$ the maximal redshift increases becoming infinite for $w\geq -1/3$.

http://arxiv.org/abs/astro-ph/0509268

Posted by: Guido Jan 29 2006, 03:34 PM

Astrophysics, abstract
astro-ph/0509268

From: Jeremy S. Heyl [view email]
Date (v1): Fri, 9 Sep 2005 21:49:22 GMT (18kb)
Date (revised v2): Tue, 8 Nov 2005 05:13:13 GMT (18kb)

The Long-Term Future of Space Travel

Authors: Jeremy S. Heyl

Comments: 5 pages, 3 figures, minor changes to reflect version accepted to PRD

The fact that we apparently live in an accelerating universe places limitations on where humans might visit. If the current energy density of the universe is dominated by a cosmological constant, a rocket could reach a galaxy observed today at a redshift of 1.7 on a one-way journey or merely 0.65 on a round trip. Unfortunately these maximal trips are impractical as they require an infinite proper time to traverse. However, calculating the rocket trajectory in detail shows that a rocketeer could nearly reach such galaxies within a lifetime (a long lifetime admittedly -- about 100 years). For less negative values of $w$ the maximal redshift increases becoming infinite for $w\geq -1/3$.

http://arxiv.org/abs/astro-ph/0509268