It has been conjectured that quantum gravity effects may cause the black-to-white hole transition due to quantum tunneling. The transition amplitude of this process is explored within the framework of the spin foam model on a 2-complex containing 56 vertices. We develop a systematic way to construct the bulk triangulation from the boundary triangulation to obtain the 2-complex. By using...
Thus far, there is no proposal for a loop quantization -- even at the level of effective dynamics -- of Kantowski-Sachs that both is exactly covariant under residual diffeomorphisms and has the correct classical limit. The models of Chiou in 2008, Joe and Singh in 2015, and other models based on similar mu-bar schemes, are the former but not the latter. The model of Ashtekar, Olmedo, and Singh...
