On the genericity of singularities in spacetimes with weakly trapped submanifolds

We investigate suitable, physically motivated conditions on spacetimes containing certain submanifolds - the so-called weakly trapped submanifolds - that ensure, in a set of neighboring metrics with respect to a convenient topology, that the phenomenon of nonspacelike geodesic incompleteness (i.e., the existence of singularities) is generic in a precise sense. We obtain two sets of results. First, we use strong Whitney topologies on spaces of Lorentzian metrics on a manifold M, in the spirit of Lerner’s [Commun. Math. Phys. 32, 19 (1973)], and obtain that while the set of singular Lorentzian metrics around a fiducial one possessing a weakly trapped submanifold Σ is not really generic, it is nevertheless prevalent in a sense we define, and thus still quite “large” in this sense. We prove versions of that result both for the case when Σ has codimension 2, and for the case of higher codimension. The second set of results explore a similar question, but now for initial data sets containing marginally outer trapped surfaces (MOTS). For this case, we use certain well-known infinite dimensional, Hilbert manifold structures on the space of initial data and use abstract functional-analytic methods based on the work of Biliotti, Javaloyes, and Piccione’s [Indiana Univ. Math. J. 58(4), 1797 (2009)] to obtain a true genericity of null geodesic incompleteness around suitable initial data sets containing MOTS.