2016/04/25 by Yoogeun Song, Song, Yoogeun, Seok Jae Park +1
Physics and Astronomy · #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #astro-ph.CO #gr-qc
paper · pdf · doi:10.48550/arxiv.1604.07639
arXiv admin note: text overlap with arXiv:1103.0300 by other authors
arxiv created 2016/04/25 · arxiv updated 2016/04/27
We study the singularity of the congruences for both timelike and null geodesic curves using the expansion of the early anisotropic Bianchi type I Universe. In this paper, we concentrate on the influence of the shear of the timelike and null geodesic congruences in the early Universe. Under some natural conditions, we derive the Raychaudhuri type equation for the expansion and the shear-related equations. Recently, scientists working on the LIGO (Laser Interferometer Gravitational-Wave Observatory) have shown many possibilities to observing the anisotropy of the primordial gravitational wave background radiation. We deduce the evolution equation for the shear that may be responsible for those observational results.