Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the Universe
Open accessAbstract
We use standard general relativity to illustrate and clarify several common misconceptions about the expansion of the universe. To show the abundance of these misconceptions we cite numerous misleading, or easily misinterpreted, statements in the literature. In the context of the new standard ΛCDM cosmology we point out confusions regarding the particle horizon, the event horizon, the ‘observable universe’ and the Hubble sphere (distance at which recession velocity = c). We show that we can observe galaxies that have, and always have had, recession velocities greater than the speed of light. We explain why this does not violate special relativity and we link these concepts to observational tests. Attempts to restrict recession velocities to less than the speed of light require a special relativistic interpretation of cosmological redshifts. We analyze apparent magnitudes of supernovae and observationally rule out the special relativistic Doppler interpretation of cosmological redshifts at a confidence level of 23σ.
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Cites
Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
Riess, A. G., Filippenko, A. V., Challis, P., Clocchiatti, A., Diercks, A., Garnavich, P. M., Gilliland, R. L., Hogan, C. J., Jha, S., Kirshner, R. P., et al. (1998) · The Astronomical Journal · doi:10.1086/300499 · Cited by 19,704 · see citing works
Measurements of Ω and Λ from 42 High‐Redshift Supernovae
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Bennett, C. L., Halpern, M., Hinshaw, G., Jarosik, N., Kogut, A., Limon, M., Meyer, S. S., Page, L., Spergel, D. N., Tucker, G. S., et al. (2003) · The Astrophysical Journal Supplement Series · doi:10.1086/377253 · Cited by 4,860 · see citing works
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Research works printed but not linked: 12
- Feynman, R. P. 1995, Feynman Lectures on Gravitation (1962/63), (Reading, Massachusetts:Addison-Wesley), p. 181. 'It makes no sense to worry about the possibility of galaxies receding from us faster than light, whatever that means, since they would never be observable by hypothesis.'
- Weinberg, S. 1977, The First Three Minutes, (New York: Bantam Books), p. 27. 'The conclusion generally drawn from this half century of observation is that the galaxies are reced- ing from us, with speeds proportional to the distance (at least for speeds not too close to that of light).' See also p. 12 and p. 25. Weinberg makes a similar statement in his 1972 text Gravitation and Cosmology (New York: Wiley), p. 417: 'a relatively close galaxy will move away from or toward the Milky Way, with a radial velocity [v rec = Ṙ(t 0 )χ].' (our emphasis). Shortly thereafter he adds a caution about SR and distant sources: 'it is neither useful nor strictly correct to interpret the frequency shifts of light from very distant sources in terms of a special-relativistic Döppler shift alone. [The reader should be warned though, that astronomers con- ventionally report even large frequency shifts in terms of a recessional velocity, a 'red shift' of v km/sec meaning that z = v/(3 × 10 5 ).]'
- Schutz, B. F. 1985, A First Course in General Relativity, (Cambridge: Cambridge University Press), p. 320. '[v = HD] cannot be exact since, for D > 1.2 × 10 26 m = 4000 Mpc, the References
- Davis, T. M., & Lineweaver, C. H. 2001, in Cosmology and Particle Physics 2000, eds. R. Durrer, J. Garcia-Bellido, & M. Shaposhnikov (New York: American Institute of Physics conference proceedings, Volume 555), 348
- Goldhaber, G., Dustua, S., Gabi, S., et al. 1997, in Thermo- nuclear Supernovae, NATO ASIC Proceedings 486, eds.
- Harrison, E. R. 1981, Cosmology: the science of the universe, 1st Edition (Cambridge: Cambridge University Press), and 2nd Edition (2000)
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- Rindler, W. 1977, Essential relativity, special, general, and cosmological, (New York: Springer)
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Cited by
Sorted by citations
The kinematic origin of the cosmological redshift
Bunn, E. F., & Hogg, D. W. (2009) · American Journal of Physics · doi:10.1119/1.3129103 · Cited by 80 · see citing works
Positive energy warp drive from hidden geometric structures
Fell, S. D. B., & Heisenberg, L. (2021) · Classical and Quantum Gravity · doi:10.1088/1361-6382/ac0e47 · Cited by 22 · see citing works
- Authors
- Davis, T. M., & Lineweaver, C. H.
- Affiliations
- UNSW Sydney (AU)
- Venue
- Publications of the Astronomical Society of Australia
- Publisher
- Cambridge University Press (CUP)
- Published
- 2004
- Volume
- 21
- Issue
- 1
- Pages
- 97-109
- ISSN
- 1323-3580 (ISSN-L)
- 1448-6083
- OpenAlex
- W2953300055
- Cited by
- 204
- References
- 3
- Citations by year
- 2026: 12 · 2025: 10 · 2024: 15 · 2023: 17 · 2022: 9 · 2021: 15 · 2020: 20 · 2019: 25 · 2018: 4 · 2017: 3 · 2016: 7 · 2015: 6 · 2014: 5 · 2013: 7 · 2012: 10
- FWCI
- 3.15
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Publications of the Astronomical Society of Australia (publishedVersion)
- arXiv (Cornell University) (submittedVersion)
- ANU Open Research (Australian National University) (submittedVersion)
- arXiv (Cornell University)
- Topics
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Cosmology and Gravitation Theories
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Galaxies: Formation, Evolution, Phenomena
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Relativity and Gravitational Theory
- Keywords
- cosmological horizon, particle horizon, event horizon, observable universe, Hubble sphere, cosmological redshift, special relativity
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