Two Roads to Antispacetime in Distorted B Phase: Kibble Wall and Half-quantum Vortex

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.