Propagation of Massive Scalar Fields in Pre-Big Bang Cosmologies

Pre-big bang geometric extensions of inflationary cosmologies

Robertson-Walker spacetimes within a large class are geometrically extended to larger cosmologies that include spacetime points with zero and negative cosmological times. In the extended cosmologies, the big bang is lightlike, and though singular, it inherits some geometric structure from the original spacetime. Spacelike geodesics are continuous across the cosmological time zero submanifold which is parameterized by the radius of Fermi space slices, i.e, by the proper distances along spacelike geodesics from a comoving observer to the big bang. The continuous extension of the metric, and the …

狄拉克可观察量用于大爆炸处规整的戈威迪宇宙学

Dirac Observables for Gowdy Cosmologies Regular at the Big Bang

本文研究了戈威迪宇宙学在大爆炸处的规整性，构造了无限个狄拉克可观察量，并通过反牛顿展开揭示了卡洛尔型引力理论的主导项。

量化极化Gowdy宇宙中的渐近速度主导

Asymptotic Velocity Domination in quantized polarized Gowdy Cosmologies

研究在量子极化Gowdy宇宙中，渐近速度主导性质通过两点函数表达，其在回溯到大爆炸时趋近于简化速度主导形式，且完整相关函数可表示为平均空间梯度的级数。

Initial data on big bang singularities in symmetric settings

In a recent article, we propose a general geometric notion of initial data on big bang singularities. This notion is of interest in its own right. However, it also serves the purpose of giving a unified perspective on many of the results in the literature. In the present article, we give a partial justification of this statement by rephrasing the results concerning Bianchi class A orthogonal stiff solutions and solutions in the $\mathbb{T}^{3}$-Gowdy symmetric vacuum setting in terms of our general geometric notion of initial data on the big bang singularity.

Symbolic Dynamics, Modular Curves, and Bianchi IX Cosmologies

It is well known that the so called Bianchi IX spacetimes with SO(3)-symmetry in a neighbourhood of the Big Bang exhibit a chaotic behaviour of typical trajectories in the backward movement of time. This behaviour (Mixmaster Model of the Universe) can be encoded by the shift of two-sided continued fractions. Exactly the same shift encodes the sequences of intersections of hyperbolic geodesics with purely imaginary axis in the upper complex half-plane, that is geodesic flow on an appropriate modular surface. A physical interpretation of this coincidence was suggested in arXiv:1402.2158: namely,…

大爆炸静止奇点形成中的完整渐近行为

Complete asymptotics in the formation of quiescent big bang singularities

本文通过证明Oude Groeniger等人结果中的解诱导奇点数据，将大爆炸奇点形成的不同数学结果统一起来，扩展了稳定大爆炸形成的结论。