A detailed study of the singularity theorems is presented. I discuss the plausibility and reasonability of their hypotheses, the applicability and implications of the theorems, as well as the theorems themselves. The consequences usually extracted from them, some of them without the necessary rigour, are widely and carefully analysed with many clarifying examples and alternative views.

Singularity Theorems and Their Consequences

The authors write the Einstein field equations for the orthogonal class B Bianchi cosmologies as an autonomous DE in terms of expansion-normalized dimensionless variables. The theory of dynamical systems is then used to give a qualitative description of the evolution of the models. Comparisons are made with other work on this problem.

https://iopscience.iop.org/article/10.1088/0264-9381/6/10/011/pdf

A dynamical systems approach to Bianchi cosmologies: Orthogonal models of class A

This is a 20-year old review on singularities and singularity theorems The main reason to submit it now is -apart from increasing its availability- to correct a very strange error that appears in the journal's online version: it contains wrong headers and footers in its 1st page This has led to many wrong citations, and to some confusion The pdf file here contains the right information 
ORIGINAL ABSTRACT: A detailed study of the singularity theorems is presented I discuss the plausibility and reasonability of their hypotheses, the applicability and implications of the theorems, as well as the theorems themselves The consequences usually extracted from them, some of them without the necessary rigour, are widely and carefully analysed with many clarifying examples and alternative views

We investigate the structure of the so-called power asymptote singularities in orthogonal spatially homogeneous solutions of the Einstein field equations with perfect fluid source. We first give a systematic survey of the different possible power asymptotes, some of which are well known, and some new, and characterize them in a coordinate-independent manner. The known orthogonal spatially homogeneous exact solutions with perfect fluid source are then classified on the basis of which power asymptote they admit. In many cases this leads to simpler forms of the known solutions, and suggests methods for deriving new solutions.

Power law singularities in orthogonal spatially homogeneous cosmologies

Inflationary cosmology has been in vogue for over a decade. However, it does not appear to provide satisfactory answers to all of the cosmological questions which provided the motivation for the theory. It is argued that quiescent cosmology and the related ideas of Penrose (1989) regarding gravitational entropy may well provide a viable alternative when formulated within the framework of isotropic singularities.

https://iopscience.iop.org/article/10.1088/0264-9381/9/2/010/pdf

The isotropic singularity in cosmology

The evolution of a class of exact spatially homogeneous cosmological models of Bianchi type VI
 h
 is discussed. It is known that solutions of type VI
 h
 cannot approach isotropy asymptotically at large times. Indeed the present class of solutions become asymptotic to an anisotropic vacuum plane wave solution. Nevertheless, for these solutions the initial anisotropy can decay, leading to a stage of finite duration in which the model is close to isotropy. Depending on the choice of parameters in the solution, this quasi-isotropic stage can commence at the initial singularity, in which case the singularity is of the type known as “isotropic” or “Friedmann-like.” The existence of this quasi-isotropic stage implies that these models can be compatible in principle with the observed universe.

P. J. Anderson

Papers

Isotropic singularities and isotropization in a class of Bianchi type-VI h cosmologies