“…Given its importance for studying the possible effects of an anisotropy in the early universe on presentday observations, many researchers have investigated the BI model from different perspectives. Examples of these studies are, string theory (Alexeyev et al 2001;Rao et al 2008;Rathore & Mandawat 2009;Bali & Gupta 2010;Rikhvitsky et al 2012), dynamical properties (Salucci & Fabbri 1983;Chimento & Forte 2006;Ellis 2006;Akarsu & Kılınç 2010a,b;Adhav et al 2011;Singh & Chaubey 2012;Appleby & Linder 2012;Mostafapoor & Grøn 2013;Pradhan et al 2013;Singh & Chaubey 2013;Ali & Rahaman 2013;Kohli & Haslam 2013), the singularity problem (Bronnikov et al 2004;Khalatnikov et al 2003;Belinskij et al 1970), the spinor/scalar field (Saha 2001a,b;Fay 2005;Saha & Boyadjiev 2004;Saha 2005Saha , 2006Kucukakca et al 2012;Pradhan et al 2012;Saha 2013;Carloni et al 2013) and perturbations in the early phase of inflation (Gümrükçüoglu & Peloso 2007;Pereira et al 2007;Dong 2010;Bali 2011;Aluri & Jain 2012;Kofman et al 2011). Separately, Maartens et al (1995b) obtain evolution equations by which matter imposes anisotropies on freely propagating CMB radiation, leading to a new model independent way of using anisotropy measurements to limit the deviations of the Universe from a FRW geometry.…”