The minimum masses of black holes from the generalized uncertainty principle and the uncertainty principle

In this paper we compare the minimum masses of Schwarzschild black hole obtained from the generalized uncertainty principle and the Heisenberg uncertainty principle. Three minimum masses are obtained. The first two are the order of Planck mass which can be normally accepted. The last one based on Scardigli’s hypothesis and consideration is about M _c ?10¹⁵ g～10²⁰ M _pl which may be problematic. Whether right or wrong, it needs the astronomical observations.     

Li production in the big bang

Li abundance is determined for 23 halo subdwarfs. About half of the stars show [Fe/H] < −1.4 and a space velocityV > 160 km s⁻¹ Li appears to be present in all our halo stars, with an abundance within about ± 0.2 dex of the value logn (Li) = 2.0 found by Spite & Spite (1982). Thus our results provide confirmation of the main conclusion of Spite & Spite.     

On the problem of big bang nucleosynthesis

Supporters of the standard Big Bang theory point to the abundances of light elements, predicted by Big Bang Nucleosynthesis (BBN) as one of the main observational supports of the theory. However, current data no longer confirm BBN. Instead, measurements of the abundances of He³, He⁴, and D clearly contradict BBN at more than a 3 level, eliminating a key support of the Big Bang.     

MBR as the relic of big bang

In this talk I outline some of the arguments in support of a cosmological and primordial origin of the observed microwave background radiation (MBR) in the early hot phase of the universe. This interpretation of the MBR is at the heart of the hot Big Bang model (HBBM) of the universe. The observed Planckian energy distribution of the microwave photons reflects the thermal equilibrium that can be set up naturally within HBBM in the dense early universe. Alternate interpretations face the challenge of extremely tight constraints on deviations from a Planckian distribution. Within HBBM, the formation of large scale structure is linked to tiny anisotropies in the angular distribution of the MBR photons. Recent measurements of these anisotropies seem to be broadly consistent with the predictions of the current scenarios of structure formation in the universe. Since these predictions are based on HBBM, the concurrence of data with theory provides additional support in favour of viewing the MBR as the relic of Big Bang.     

Some critiques of the big bang cosmology

Still more shocking than the metaphysical assumption of some initial singularity, is the constant insistence upon the so-called cosmological principle of “homogeneity” and “isotropy” of the Universe. Observations do contradict this principle. And to me, the inhomogeneous, fractal at least on a certain scale range, of the distribution of matter is in itself an important cosmological fact, hitherto almost neglected. Moreover difficultties as to the applicability of the second principle of thermodynamics, observations of abnormal redshifts, etc., are casting large doubts not only upon the standard cosmological models, but even on the interpretation of the observed redshift as due solely to a universal expansion.     

Effect of holographic principle and generalized uncertainty principle on the semiclassical Parikh-Wilczek tunneling radiation of black holes

In the present paper, based on the generalized uncertainty principle, the Parikh-Wilczek black hole tunneling radiation is studied. It is shown that the black hole tunneling radiation receives a correction. Furthermore a bound on the tunneling approach, is shown to be valid when, based on the holographic principle, a bound applied to the black hole entropy.     

The generalized uncertainty principle and the thermodynamic quantities near a black hole

The continuous complex Morlet wavelet transform is used to investigate temporal rotation cycle length of daily sunspot areas from May 9, 1874 to February 28, 2010, from a global point of view. The rotation cycle length of the Sun is found to have a secular trend: it decreased from the year of 1874 to 1950s, and since then the Sun is rotating more and more speedily in the long run. The rotation period appears around the maximum times of the Schwabe cycles with statistical significance, but in the minimum times it is always statistically insignificant, although it is found to have no relation with the Schwabe cycle. The period length of the rotation cycle displays the significant periods of 2.61 and 5.77 years.     

Generalized limits to the number of light particle degrees of freedom from big bang nucleosynthesis

We compute the big bang nucleosynthesis limit on the number of light neutrino degrees of freedom in a model-independent likelihood analysis based on the abundances of ⁴He and ⁷Li. We use the two-dimensional likelihood functions to simultaneously constrain the baryon-to-photon ratio and the number of light neutrinos for a range of ⁴He abundances Y_p = 0.225–0.250, as well as a range in primordial ⁷Li abundances from (1.6 to 4.1) ×10⁻¹⁰. For (⁷Li/H)_p = 1.6 × 10⁻¹⁰, as can be inferred from the ⁷Li data from Population II halo stars, the upper limit to N_ν based on the current best estimate of the primordial ⁴He abundance of Y_p = 0.238 is N_ν < 4.3 and varies from N_ν < 3.3 (at 95% C.L.) when Y_p = 0.225 to N_ν < 5.3 when Y_p = 0.250. If ⁷Li is depleted in these stars the upper limit to N_ν is relaxed. Taking (⁷Li/H)_p = 4.1 × 10⁻¹⁰, the limit varies from N_ν < 3.9 when Y_p = 0.225 to N_ν 6 when Y_p = 0.250. We also consider the consequences on the upper limit to N_ν if recent observations of deuterium in high-redshift quasar absorption-line systems are confirmed.     

Cosmological bang as a consequence of a sudden change in the quantum statistics of nuclear matter

An heuristic hypothesis is advanced about dominant Bose statistics during the transition from the radiation era to the matter era in the early universe. It is shown that large scale Bose condensation of matter from baryon-antibaryon pairs is possible, as a result of which a colossal amount of mass may accumulate in a volume of cosmic scale. At a threshold density of matter, the structural bosons decay into the fermions of which they are composed, so that a sudden change in the symmetry of the wave functions of the particles causes a jump from Bose-Einstein to Fermi-Dirac statistics. This involves a large scale phase transition with an enormous pressure jump which may show up as a cosmological bang at the beginning of the matter era. __________ Translated from Astrofizika, Vol. 51, No. 1, pp. 161–172 (February 2008).     

Thermodynamics under the extended uncertainty principle background: Q−ϕ criticality analysis

The study of thermodynamics in the background of the “extended uncertainty principle (EUP)” comes into interest in recent eras. In this article, we consider a charged black hole (BH) in higher dimensional space–time and present the thermodynamic parameters, based on a semiclassical framework, initially. Then we extend the same within the EUP background. We also analyze the $Q-\varphi$ criticality and find the critical points (${\varphi }_c,Q_c$ and $T_c$) when $Q-\varphi$ criticality appears. We study the effects of EUP on phase transition for higher dimensions ($d=5$) by plotting the $Q-\varphi$ diagrams. Further, we investigate the stability (thermal and global) of the BHs by employing the specific heat and the Gibbs free energy without and within EUP correction and compare the results with the Schwarzschild BHs in higher dimensions.     

Microscopic black hole detection in UHECR: the double bang signature

According to recent conjectures on the existence of large extra dimensions in our universe, black holes could be produced during the interaction of Ultra High Energy Cosmic Rays with the atmosphere. However, and so far, the proposed signatures are based on statistical effects, not allowing identification on an event by event basis, and may lead to large uncertainties. In this note, events with a double bang topology, where the production and instantaneous decay of a microscopic black hole (first bang) is followed, at a measurable distance, by the decay of an energetic tau lepton (second bang) are proposed as an almost background free signature. The characteristics of these events and the capability of large cosmic ray experiments to detect them are discussed.     

Holographic dark energy with linearly varying deceleration parameter and escaping big rip singularity of the Bianchi type-V universe

The present work deals with the accretion of two minimally interacting fluids: dark matter and a hypothetical isotropic fluid as the holographic dark energy components onto black hole and wormhole in a spatially homogeneous and anisotropic Bianchi type-V universe. To obtain an exact solution of the Einstein’s field equations, we use the assumption of linearly varying deceleration parameter. Solution describes effectively the actual acceleration and indicates a big rip type future singularity of the universe. We have studied the evolution of the mass of black hole and the wormhole embedded in this anisotropic universe in order to reproduce a stable universe protected against future-time singularity. It is observed that the accretion of these dark components leads to a gradual decrease and increase of black hole and wormhole mass respectively. Finally, we have found that contrary to our previous case (Sarkar in Astrophys. Space. Sci. 341:651, 2014a), the big rip singularity of the universe with a divergent Hubble parameter of this dark energy model may be avoided by a big trip.     

Thermodynamics of Vaidya-Bonner-de Sitter space time based on the generalized space-time uncertainty

In each static or stationary space time k is just surface gravity of the horizon, but in the of Vaidya-Bonner-de Sitter space time, it is no longer the surface gravity of the event horizon. This property makes the Vaidya-Bonner as an important horizon. In this paper, the entropy of Vaidya-Bonner-de Sitter space time is calculated. In continue, employing the generalized uncertainty principle, quantum gravitational corrections to the entropy of Vaidya-Bonner space time is studied.     

Generalized uncertainty principle and Bekenstein-Hawking entropy in tunneling rate of Kerr black hole

We study the effects of the generalized uncertainty principle in the tunneling formalism for Hawking radiation to evaluate the quantum-corrected Hawking temperature and entropy for a Kerr black hole. By assumption of a spatially flat universe accompanied with expansion of metric, the modified area and entropy of Kerr black hole are calculated and we could obtain an expression for entropy of black hole that is changing with respect to time and Bekenstein-Hawking temperature.     

The generalized second law of thermodynamics for the interacting in f(T) gravity

We study the validity of the generalized second law (GSL) of gravitational thermodynamics in a non-flat FRW universe containing the interacting in f(T) gravity. We consider that the boundary of the universe to be confined by the dynamical apparent horizon in FRW universe. In general, we discuss the effective equation of state, deceleration parameter and GLS in this framewok. Also, we find that the interacting-term Q modifies these quantities and in particular, the evolution of the total entropy, results in an increases on the GLS of thermodynamic, by a factor $4\pi R_{A}^{3} Q/3$ . By using a viable f(T) gravity with an exponential dependence on the torsion, we develop a model where the interaction term is related to the total energy density of matter. Here, we find that a crossing of phantom divide line is possible for the interacting-f(T) model.     

The branch-cut quantum gravity with a self-coupling inflation scalar field: The wave function of the Universe

This paper focuses on the implications of a commutative formulation that integrates branch-cutting cosmology, the Wheeler–DeWitt equation, and Hořava–Lifshitz quantum gravity. Building on a mini-superspace structure, we explore the impact of an inflaton-type scalar field on the wave function of the Universe. Specifically analyzing the dynamical solutions of branch-cut gravity within a mini-superspace framework, we emphasize the scalar field's influence on the evolution of the evolution of the wave function of the Universe. Our research unveils a helix-like function that characterizes a topologically foliated spacetime structure. The starting point is the Hořava–Lifshitz action, which depends on the scalar curvature of the branched Universe and its derivatives, with running coupling constants denoted as $g_i$. The corresponding wave equations are derived and are resolved. The commutative quantum gravity approach preserves the diffeomorphism property of General Relativity, maintaining compatibility with the Arnowitt–Deser–Misner formalism. Additionally, we delve into a mini-superspace of variables, incorporating scalar-inflaton fields and exploring inflationary models, particularly chaotic and nonchaotic scenarios. We obtained solutions for the wave equations without recurring to numerical approximations.     

Noncommutative branch-cut quantum gravity with a self-coupling inflaton scalar field: The wave function of the Universe

This article focuses on the implications of a noncommutative formulation of branch-cut quantum gravity. Based on a mini-superspace structure that obeys the noncommutative Poisson algebra, combined with the Wheeler–DeWitt equation and Hořava–Lifshitz quantum gravity, we explore the impact of a scalar field of the inflaton-type in the evolution of the Universe's wave function. Taking as a starting point the Hořava–Lifshitz action, which depends on the scalar curvature of the branched Universe and its derivatives, the corresponding wave equations are derived and solved. The noncommutative quantum gravity approach adopted preserves the diffeomorphism property of General Relativity, maintaining compatibility with the Arnowitt–Deser–Misner Formalism. In this work we delve deeper into a mini-superspace of noncommutative variables, incorporating scalar inflaton fields and exploring inflationary models, particularly chaotic and nonchaotic scenarios. We obtained solutions to the wave equations without resorting to numerical approximations. The results indicate that the noncommutative algebraic space captures low and high spacetime scales, driving the exponential acceleration of the Universe.     

Nonlinear electrodynamics in f(T) gravity and generalized second law of thermodynamics

In this paper, we study the nonlinear electrodynamics in the framework of f(T) gravity for FRW universe along with dust matter, magnetic and torsion contributions. We evaluate the equation of state and deceleration parameters to explore the accelerated expansion of the universe. The validity of generalized second law of thermodynamics for Hubble and event horizons is also investigated in this scenario. For this purpose, we assume polelike and power-law forms of scale factor and construct f(T) models. The graphical behavior of the cosmological parameters versus smaller values of redshift z represent the accelerated expansion of the universe. It turns out that the generalized second law of thermodynamics holds for all values of z with Hubble and event horizons in polelike scale factor whereas for power-law form, it holds in a specific range of z for both horizons.