It is shown that the curved spacetime induced in a thin film of superfluid 3He-A by the presence of symmetric vortices with the unbroken symmetry phase, admits the existence of closed timelike curves through which only superfluid clusters formed by anti-3He atoms can travel and violate causality.
Cite
@article{arxiv.cond-mat/9809140,
title = {Closed timelike curves in superfluid $^{3}$He},
author = {Pedro F. Gonzalez-Diaz and Carmen L. Siguenza},
journal= {arXiv preprint arXiv:cond-mat/9809140},
year = {2009}
}