Second law of gravitational thermodynamics in the locally rotationally symmetric Bianchi type-II universe

Korunur, Murat

doi:10.3906/fiz-1703-10

Cited by 3 publications

(1 citation statement)

References 55 publications

(60 reference statements)

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“…Accordingly, from a thermodynamic point of view, Jacobson first showed that the equation of state of space-time is exactly the standard Einstein equations. This is a significant step because determining the relationship between thermodynamics and gravity has made it easier to consider the concept of dark a e-mails: aliihsan.keskin@batman.edu.tr; alikeskin039@gmail.com (corresponding author) b e-mail: kadri.kurt@batman.edu.tr energy from a thermodynamic perspective [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. In this direction, cosmic spacetime, as a whole, can be considered a thermodynamics system to study the second law of thermodynamics (cosmological entropy law).…”

Section: Introductionmentioning

confidence: 99%

Constant-roll inflation field with Tsallis entopic proposal

Keskin

Kurt

2023

Eur. Phys. J. C

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In this work, we investigate the high-energy era of the universe from the constant-roll condition perspective by taking the Friedmann equation, which is modified by a non-additive Tsallis entropic proposal. In the framework of the observational data, we determine the constant-roll parameter. Under the fixed field condition of the constant-roll parameter, for the wide range of the power-term of the chaotic potentials, $$\sim \phi ^{n}$$ ∼ ϕ n , which involves some string-chaotic potential models, $$n=\frac{2}{3}$$ n = 2 3 , $$n=\frac{4}{5}$$ n = 4 5 , the non-additive (nonextensive) Tsallis parameter is analyzed graphically. The resulting analysis shows that, in addition to a quasi-de Sitter phase, any value of the range $$0.5<n<1.2$$ 0.5 < n < 1.2 points to a dynamical form of the dark energy (quintessence) in the early universe. It implies that n values in the range may be included in string-chaotic potential models. The non-additive Tsallis parameter provides this with the help of its negative values in the constant-roll field.

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Section: Introductionmentioning

confidence: 99%

Constant-roll inflation field with Tsallis entopic proposal

Keskin

Kurt

2023

Eur. Phys. J. C

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Cosmology in scalar–tensor–vector theory via thermodynamics

et al. 2018

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Assuming the universe as a thermodynamical system, the second law of thermodynamics can be extended to another form including the sum of matter and horizon entropies, which is called the generalized second law of thermodynamics. The generalized form of the second law (GSL) is universal which means it holds both in non-equilibrium and equilibrium pictures of thermodynamics. Considering the universe is bounded by a dynamical apparent horizon, we investigate the nature of entropy function for the validity of GSL in the scalar–tensor–vector (STEVE) theory of gravity.

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The fractal structure of high-energy era of the universe

Keskin,

Kurt

2024

Int. J. Geom. Methods Mod. Phys.

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This study examines the structure of the universe during its high-energy era. In this context, we examine Barrow’s proposal of entropy, which forecasts a fractal configuration for the geometric properties of the black hole’s horizon. By applying the principles of thermodynamics, we get the equation of motion using the Barrow entropic consideration. A quasi-de Sitter phase, in which fractal and non-fractal states may coexist, is determined. This is an uncertainty state (coexistence of fractal and non-fractal states), and so a deformation for de Sitter spacetime, which contains a high-energy scale in the framework of the COBE normalization. With the kinetic energy term of the inflation field, we remove this ambiguity owing to the field oscillations. However, the oscillatory behavior of the inflation field continues and causes the universe to enter a new phase state. At this point, in which the inflation field oscillations are over, we obtain a solution that provides the universe transition to the radiation and dust phases.

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Second law of gravitational thermodynamics in the locally rotationally symmetric Bianchi type-II universe

Cited by 3 publications

References 55 publications

Constant-roll inflation field with Tsallis entopic proposal

Constant-roll inflation field with Tsallis entopic proposal

Cosmology in scalar–tensor–vector theory via thermodynamics

The fractal structure of high-energy era of the universe

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