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Inspired by the Wald-Kodama entropy $S=A/(4G_{\text{eff}})$ where $A$ is the horizon area and $G_{\text{eff}}$ is the effective gravitational coupling strength in modified gravity with field equation $R_{\mu\nu}-Rg_{\mu\nu}/2=$ $8\pi…

General Relativity and Quantum Cosmology · Physics 2015-07-14 David Wenjie Tian , Ivan Booth

It is shown that a first-order relativistic perturbation theory for the open, flat or closed Friedmann-Lemaitre-Robertson-Walker universe admits one, and only one, gauge-invariant quantity which describes the perturbation to the energy…

General Relativity and Quantum Cosmology · Physics 2014-03-25 P. G. Miedema

In the paper, hep-th/0501055 (R.G. Cai and S.P. Kim, JHEP {\bf 0502}, 050 (2005)), it is shown that by applying the first law of thermodynamics to the apparent horizon of an FRW universe and assuming the geometric entropy given by a quarter…

High Energy Physics - Theory · Physics 2008-11-26 M. Akbar , Rong-Gen Cai

We present a bouquet of continuity bounds for quantum entropies, falling broadly into two classes: First, a tight analysis of the Alicki-Fannes continuity bounds for the conditional von Neumann entropy, reaching almost the best possible…

Quantum Physics · Physics 2016-09-06 Andreas Winter

We derive a unified expansion law for our universe from the first law of thermodynamics on the apparent horizon, where entropic evolution depicts the emergence of cosmic space. The derivation advances a general form for degrees of freedom…

General Relativity and Quantum Cosmology · Physics 2023-02-22 Hassan Basari V. T. , P. B. Krishna , Titus K. Mathew

Researches in the several decades have shown that the dynamics of gravity is closely related to thermodynamics of the horizon. In this paper, we derive the Friedmann acceleration equation based on the idea of "emergence of space" and…

General Relativity and Quantum Cosmology · Physics 2018-09-03 Fei-Quan Tu , Yi-Xin Chen , Bin Sun , You-Chang Yang

Padmanabhan in his paper [arxiv: 1206.4916] put forth an intriguing idea arguing that the accelerated expansion of the universse can be viewed as the emergence of cosmic space as cosmic time progresses, with the expansion triggered due to…

General Relativity and Quantum Cosmology · Physics 2018-12-26 Mahith M. , Krishna P. B. , Titus K. Mathew

Despite all fundamental objections against Newtonian concepts in cosmology, the Friedmann equation derives from these in an astoundingly simple way through application of the shell theorem and conservation of Newtonian energy in an infinite…

General Relativity and Quantum Cosmology · Physics 2017-04-05 Herman Telkamp

It is shown that a first-order cosmological perturbation theory for the open, flat and closed Friedmann-Lema\^itre-Robertson-Walker universes admits one, and only one, gauge-invariant variable which describes the perturbation to the energy…

General Relativity and Quantum Cosmology · Physics 2014-10-02 P. G. Miedema , W. A. van Leeuwen

In `entropic cosmology', instead of a cosmological constant $\Lambda$, an extra driving term is added to the Friedmann equation and the acceleration equation, taking into account the entropy and the temperature on the horizon of the…

Cosmology and Nongalactic Astrophysics · Physics 2013-03-14 Nobuyoshi Komatsu , Shigeo Kimura

By studying a modified Friedmann equation which arises in an extension of general relativity which accommodates a time-dependent fundamental length $L(t)$, we consider cosmological models where the scale factor diverges with an essential…

Astrophysics · Physics 2014-10-13 Paul H. Frampton , Tomo Takahashi

Utilizing Kaniadakis entropy associated with the apparent horizon of the Friedmann-Robertson-Walker (FRW) Universe and applying the emergence of cosmic space paradigm, we deduce the modified Friedmann equation for a non-flat…

General Relativity and Quantum Cosmology · Physics 2024-05-08 Pranav Prasanthan , Sarath Nelleri , Navaneeth Poonthottathil , Sreejith E K

In a recent paper [arXiv:1206.4916] by T. Padmanabhan, it was argued that our universe provides an ideal setup to stress the issue that cosmic space is emergent as cosmic time progresses and that the expansion of the universe is due to the…

General Relativity and Quantum Cosmology · Physics 2012-11-09 Rong-Gen Cai

Using techniques proposed in [Sason, IEEE Trans. Inf. Th. 59, 7118 (2013)] and [Becker, Datta and Jabbour, IEEE Trans. Inf. Th. 69, 4128 (2023)], and based on the results from the latter, we construct a globally optimal continuity bound for…

Quantum Physics · Physics 2025-02-27 S. Becker , N. Datta , M. G. Jabbour , M. E. Shirokov

The recent research on the connection between gravity and thermodynamics suggests that gravity could be an emergent phenomenon. Following this, Padmanabhan proposed a novel idea that the expansion of the universe can be interpreted as…

General Relativity and Quantum Cosmology · Physics 2022-06-22 P. B. Krishna , Hassan Basari V. T. , Titus K Mathew

The accelerated expansion of the universe can be interpreted as a quest for satisfying holographic equipartition. It can be expressed by a simple law, $\Delta V = \Delta t\left(N_{surf}- N_{bulk}\right)$ which leads to the standard…

General Relativity and Quantum Cosmology · Physics 2019-02-06 Krishna P B , Titus K Mathew

According to the quantum deformation approach to quantum gravity, the thermodynamical entropy of a quantum-deformed (q-deformed) black hole with horizon area $A$ established by Jalalzadeh is expressed as $S_q = \pi\sin \left(…

General Relativity and Quantum Cosmology · Physics 2024-05-20 Jianming Chen , Gerui Chen

The thermodynamic properties of loop quantum cosmology (LQC) without considering the Lorentz term were established in \cite{Zhu09}. In this paper, we extend this result to the recent proposed new model of LQC with the Lorentz term. We…

General Relativity and Quantum Cosmology · Physics 2021-11-11 Xiangdong Zhang

We consider perturbative modifications of the Friedmann equations in terms of energy density corresponding to modified theories of gravity proposed as an alternative route to comply with the observed accelerated expansion of the universe.…

General Relativity and Quantum Cosmology · Physics 2015-05-13 L. Fernández-Jambrina , R. Lazkoz

The strongest evidence for dark energy comes presently from geometric techniques such as the supernova distance-redshift relation. By combining the measured expansion history with the Friedmann equation one determines the energy density and…

Astrophysics · Physics 2008-11-26 Edmund Bertschinger