Crossing the singularity of a gravitational wave collision

A reformulation of general relativity inspired by the Belinski-Khalatnikov-Lifshitz conjecture had been introduced by Ashtekar, Henderson, and Sloan which is based on variables closely related to the basic variables of loop quantum gravity, thereby providing a way of classically analyzing singularities that may be carried over to the quantum theory. It is reasonable to expect that these variables are regular at generic spacelike singularities. This has been shown on various examples-particularly, cosmological spacetimes. In this study we extend this analysis to the singularities of gravitational wave collision spacetimes, which are the result of the mutual focusing of the two waves. We focus on two specific examples and explicitly confirm that the said variables are regular at the singularity and can be smoothly continued beyond it.