Dynamics of chaotic inflation with variable space dimension

Nasseri, Forough

doi:10.1016/s0370-2693(02)01995-0

Cited by 5 publications

(22 citation statements)

References 20 publications

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“…Although these assumptions appear to be rather artificial and not based on any particular natural grounds one might expect in quantum gravity, they do nonetheless provide the basis for a novel toy model, which has been extensively studied in Refs. [2,3,4,5]. It would appear to the author of this paper to be time to ask the question, can such models be ruled out observationally?…”

Section: Reasons For Ruling the Model Outmentioning

confidence: 95%

“…The model that we have studied in Refs. [2,3,4,5] makes a rather different, but equally ad hoc assumption, namely that there is a particular Planck scale ℓ P = 1.6160 × 10 −33 cm which is absolutely fixed, and the dimension of space is then prescribed to vary according to Eq. (3), varying from some initial dimension D P , when the scale factor was ℓ P = 1.6160 × 10 −33 cm.…”

Section: Reasons For Ruling the Model Outmentioning

confidence: 99%

“…On the other hand, the assumption that the dimensions change at the constant rate prescribed in Refs. [2,3,4,5], is difficult to justify on physical grounds. One might expect that during the early Universe the dimension rapidly altered and then stabilized.…”

Section: Reasons For Ruling the Model Outmentioning

confidence: 99%

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Limits on the Time Evolution of Space Dimensions From Newton's Constant

Nasseri

2005

Int. J. Mod. Phys. D

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Limits are imposed upon the possible rate of change of extra spatial dimensions in a decrumpling model Universe with time variable spatial dimensions (TVSD) by considering the time variation of (1+3)dimensional Newton's constant. Previous studies on the time variation of (1+3)-dimensional Newton's constant in TVSD theory had not been included the effects of the volume of the extra dimensions and the effects of the surface area of the unit sphere in D-space dimensions. Our main result is that the absolute value of the present rate of change of spatial dimensions to be less than about 10 −14 yr −1 . Our results would appear to provide a prima facie case for ruling the TVSD model out. We show that based on observational bounds on the present-day variation of Newton's constant, one would have to conclude that the spatial dimension of the Universe when the Universe was "at the Planck scale" to be less than or equal to 3.09. If the dimension of space when the Universe was "at the Planck scale" is constrained to be fractional and very close to 3, then the whole edifice of TVSD model loses credibility.

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Section: Reasons For Ruling the Model Outmentioning

confidence: 95%

Section: Reasons For Ruling the Model Outmentioning

confidence: 99%

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Limits on the Time Evolution of Space Dimensions From Newton's Constant

Nasseri

2005

Int. J. Mod. Phys. D

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“…2,3 Chaotic inflation in decrumpling model and its dynamical solutions have also been studied. 4,5 The concept of decrumpling expansion of the Universe is inspired by the idea of decrumpling coming from polymer physics. 1,2 In this model the fundamental building blocks of the Universe are like cells with arbitrary dimensions having in each dimension a characteristic size δ which may be of the order of the Planck length O(10 −33 cm) or even smaller so that the minimum physical radius of the Universe is δ.…”

Section: Review Of Decrumpling or Tvsd Modelmentioning

confidence: 99%

Noncommutative Decrumpling Inflation and Running of the Spectral Index

Nasseri

Alavi

2005

Int. J. Mod. Phys. D

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We present a new inflation model, known as noncommutative decrumpling inflation, in which space has noncommutative geometry with time variability of the number of spatial dimensions. Within the framework of noncommutative decrumpling inflation, we compute both the spectral index and its running. Our results show the effects of both time variability of the number of spatial dimensions and noncommutative geometry on the spectral index and its running. Two classes of examples have been studied and comparisons made with the standard slow-roll formulae. We conclude that the effects of noncommutative geometry on the spectral index and its running are much smaller than the effects of time variability of spatial dimensions.

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“…[1][2][3][4][5][6][7] In this paper, we study the time variation of the fine structure constant in decrumpling or TVSD model. a…”

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confidence: 99%