A critical review of inflation
Open accessAbstract
The theory of cosmic inflation offers an attractive resolution of some of the great paradoxes in cosmology: why the universe is so large, flat and uniform on large scales, and how density variations arose. Inflation has rightly dominated cosmological thinking for the past two decades, helping stimulate the development of high-precision observational programmes. The survival of simple inflationary models in the face of an impressive observational onslaught has been interpreted as convincing evidence of the correctness of the basic idea. In this paper, I review inflation, but highlight its weaknesses, explaining my reasons for believing that a more complete theory may supersede inflation without necessarily incorporating it.
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The evidence that inflation actually happened is quite strong, though not indubitable.
“The evidence is quite strong, though not indubitable (Turok 2002;Brandenberger 2011).”
From The Fine-Tuning of the Universe for Intelligent Life (2012) · cites this paper as Turok 2002
Section 4, “Inflationary perturbations” (page unavailable), says observations had tested the HPZ hypothesis rather than inflation itself, and that the observed pattern is not specific to inflation. Section 6 also describes a paucity of observational tests. Turok thus cautions against treating the evidence as strong evidence that inflation actually happened. (LLM, conf=0.84)
Checked by a reasoning model — may be wrong.
Experimental — accuracy not yet measuredA given inflationary model will only predict a life-permitting value for Q if the parameters of the inflaton potential are suitably fine-tuned.
“A given inflationary model will predict Q, and it will only predict a lifepermitting value for Q if the parameters of the inflaton potential are suitably fine-tuned.”
From The Fine-Tuning of the Universe for Intelligent Life (2012) · cites this paper as Turok (2002)
Section 3, “Inflationary quantum fluctuations” (page not available), says that in the power-law inflaton-potential model discussed, obtaining the observed density-perturbation amplitude requires adjusting the coupling to a very small value, which it calls a fine-tuning problem. It does not establish a life-permitting range for Q or show that every given inflationary model requires such tuning. (LLM, conf=0.86)
Experimental — accuracy not yet measuredTo obtain density perturbations of the level required by observations, the coupling m for a power law potential mf^n must be very small, ~10^-13 in Planck units.
“to obtain density perturbations of the level required by observations ywe need to adjust the coupling m [for a power law potential mf n ] to be very small, ,10 À13 in Planck units.This is the famous fine-tuning problem of inflation”
From The Fine-Tuning of the Universe for Intelligent Life (2012) · cites this paper as Turok (2002)
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References 39 · Cited by 58
Research works printed but not linked: 19
- [8]8. Gott J R 1986 Inner Space, Outer Space ed E W Kolb et al (Chicago, IL: University of Chicago Press)
- [9]9. Gratton S, Lewis A and Turok N 2002 Phys. Rev. D 65 043513 (Preprint astro-ph/0111012) · arXiv
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- [29]29. Linde A D 1986 Phys. Lett. B 175 395 The stochastic description of inflationary quantum fluctuations was developed in Starobinsky A A 1986 Field Theory Quantum Gravity and Strings (Lecture Notes in Physics vol 246) ed H J de Vega and N Sanchez (Berlin: Springer) p 107
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- [34]34. Guth has given a summary in Guth A 2000 Preprints astro-ph/0002156 and astro-ph/0101507 · arXiv
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- [43]43. Gibbons G W 1984 Aspects of supergravity theories GIFT Seminar on Supersymmetry, Supergravity and Related Topics ed F del Aguila, J A de Azcarraga and L E Ibanez (Singapore: World Scientific)
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- Authors
- Turok, N.
- Corresponding author
- Turok, Neil
- ORCID
- Turok, Neil
- Venue
- Classical and Quantum Gravity
- Publisher
- IOP Publishing
- Published
- 2002-06-12
- Volume
- 19
- Issue
- 13
- Pages
- 3449-3467
- ISSN
- 0264-9381 (ISSN-L)
- OpenAlex
- W2005096205
- Semantic Scholar
- e09565caffeb9ce1279876d62c40ecae9e809f9f
- Cited by
- 58
- References
- 39
- Citations by year
- 2025: 1 · 2024: 5 · 2023: 5 · 2022: 2 · 2021: 1 · 2020: 1 · 2019: 2 · 2018: 2 · 2017: 4 · 2016: 3 · 2015: 3 · 2014: 3 · 2013: 3 · 2012: 2
- FWCI
- 2.33
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Classical and Quantum Gravity (publishedVersion)
- Topics
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Cosmology and Gravitation Theories
- Physical Sciences › Physics and Astronomy › Statistical and Nonlinear Physics › Noncommutative and Quantum Gravity Theories
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Galaxies: Formation, Evolution, Phenomena
- Keywords
- cosmic inflation, flatness problem, horizon problem, density perturbations, observational cosmology, alternative to inflation, cosmological models
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