The branch-cut quantum gravity with a self-coupling inflation scalar field: Dynamical equations     

Fridolin Weber  Peter O. Hess  Benno Bodmann  José de Freitas Pacheco  Dimiter Hadjimichef  Marcelo Marzola  Geovane Naysinger  Moisés Razeira  César A. Zen Vasconcellos 《Astronomische Nachrichten》2024,345(2-3):e230152

This article focuses on the implications of the recently developed commutative formulation based on branch-cutting cosmology, the Wheeler–DeWitt equation, and Hořava–Lifshitz quantum gravity. Assuming a mini-superspace of variables, we explore the impact of an inflaton-type scalar field $\varphi (t)$ on the dynamical equations that describe the trajectories evolution of the scale factor of the Universe, characterized by the dimensionless helix-like function ${\ln }^{-1}[\beta (t)]$. This scale factor characterizes a Riemannian foliated spacetime that topologically overcomes the big bang and big crunch singularities. Taking the Hořava–Lifshitz action as our starting point, which depends on the scalar curvature of the branched Universe and its derivatives, with running coupling constants denoted as $g_i$, the commutative quantum gravity approach preserves the diffeomorphism property of General Relativity, maintaining compatibility with the Arnowitt–Deser–Misner formalism. We investigate both chaotic and nonchaotic inflationary scenarios, demonstrating the sensitivity of the branch-cut Universe's dynamics to initial conditions and parameterizations of primordial matter content. The results suggest a continuous connection of Riemann surfaces, overcoming primordial singularities and exhibiting diverse evolutionary behaviors, from big crunch to moderate acceleration.  相似文献   

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

Peter O. Hess  Fridolin Weber  Benno Bodmann  José de Freitas Pacheco  Dimiter Hadjimichef  Marcelo Netz-Marzola  Geovane Naysinger  Moisés Razeira  César A. Zen Vasconcellos 《Astronomische Nachrichten》2024,345(2-3):e230162

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.  相似文献   

New exact solutions for power-law inflation Friedmann models     

H.-J. Schmidt 《Astronomische Nachrichten》1990,311(3):165-168

We consider the spatially flat Friedmann model For a ≈ t^p, especially, if p ≥ 1, this is called power-law inflation. For the Lagrangian L = R^m with p = − (m − 1) (2m − 1)/(m − 2) power-law inflation is an exact solution, as it is for Einstein gravity with a minimally coupled scalar field ϕ in an exponential potential V(ϕ) = exp (μϕ) and also for the higher-dimensional Einstein equation with a special Kaluza-Klein ansatz. The synchronized coordinates are not adapted to allow a closed-form solution, so we write The general solutions reads Q(a) = (a^b + C)^f/b with free integration constant C (C = 0 gives exact power-law inflation) and m-dependent values b and f: f = −2 + 1/p, b = (4m − 5)/(m − 1). Finally, special solutions for the closed and open Friedmann model are found.  相似文献   

Quasi-de Sitter stage of the cosmic evolution,de Sitter space-time,and creation of matter     

U. Kasper 《Astronomische Nachrichten》1990,311(3):150-150

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Isotropization by scalar field driven inflation and the cosmological quantum boundary     

V. N. Lukash  H.-J. Schmidt 《Astronomische Nachrichten》1988,309(1):25-31

We derive the Wheeler-de Witt equation for the scalar field of mass m > 0 in a Bianchi-type I universe. We argue that classical trajectories become possible at h² ⩽ αt_p^-2, h being the mean Hubble value and t_p the Planck time. We feel justified to set the numerical constant α ≈︁ 1. We discuss this condition in geometrically invariant quantities and compare it with ⩽t_p^-4. The proposed quantum boundary of classical trajectories represents a 3-dimensional sphere in the 4-space of the dynamical system. Equipartition of the initial energy over field (m < m_p) and shear variables at the quantum boundary will cause inflation with a probability p of the order p = 1 - m/m_p thus, p = 1 - 10^-4 for m taken from GUT. In the course of the inflationary stage the initially arbitrarily large shear-anisotropy exponentially decays.  相似文献   

救捞工程中爆炸充气气囊设计     

詹发民  王兴雁  周方毅  许明清  张可玉 《海洋工程》2010,28(1)

将炸药爆炸燃烧所产生的高压气体作为气源,对气囊系统进行快速充气,利用充盈气囊所提供的浮力可完成对水下沉物的打捞。爆炸充气气囊是一种新型水下打捞作业器材,介绍了它的工作原理、系统组成及功能、性能特点和实际应用情况等,对于救捞工程作业具有重要的实用价值。  相似文献   

Double inflation and the evolution of perturbations     

S. Gottlber 《Astronomische Nachrichten》1990,311(3):182-182

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