 We conclude with one final potential problem which threatens to render all Malament-Hogarth spacetimes physically unreasonable. Penrose (1979) has conjectured that all physically reasonable spacetimes are free of a certain type of “naked singularities” and the breakdown of determinism they bring. Whether Penrose’s conjecture is true or not is the subject of much debate (Earman 1995). But it turns out that every Malament-Hogarth spacetime harbors these naked singularities (Hogarth 1992). Even so, the breakdown of determinism guaranteed in such spacetimes does not seem to preclude the construction of Malament-Hogarth “machines” which could possibly bring about supertasks from initial data (Earman et al. 2016; Manchak 2018). Stepping back, we find that it is still an open question whether Malament-Hogarth spacetimes are simply artifact of the formalism of general relativity or if the kind of bifurcated supertask they suggest can be implemented in our own universe. 