Volovik , G E 2019 , ' Two Roads to Antispacetime in Distorted B Phase : Kibble Wall and Half-quantum Vortex ' , JETP Letters , vol. 109 , no. 8 , pp. 499-501 . https://doi.org/10.1134/S0021364019080034
Abstract:
We consider the emergent tetrad gravity and the analog of antispacetime realized in the recent experiments on the composite defects in superfluid 3 He (J.T. Mäkinen, et al., Nat. Comm. 10, 237 (2019)): the Kibble walls bounded by strings (the half quantum vortices). The antispacetime can be reached in two different ways: by the “safe” route around the Alice string or by dangerous route across the Kibble wall. This consideration also suggests the scenario of the formation of the discrete symmetry – the parity P in Dirac equations–from the continuous symmetry existing on the more fundamental level.