  What about models involving two temporal dimensions, or parallel universes—do they allow for coherent scenarios in which the past is changed?[13]  There is certainly no contradiction in saying that the time traveller burns all her diaries at midnight on her fortieth birthday in 1976 in universe 1 (or at hypertime A), and does not burn all her diaries at midnight on her fortieth birthday in 1976 in universe 2 (or at hypertime B). The question is whether this kind of story involves changing the past in the sense originally envisaged: righting the wrongs of history, preventing subsequently regretted actions, and so on. Goddu (2003) and van  Inwagen (2010) argue that it does (in the context of particular hypertime models), while Smith (1997, 365–6; 2015) argues that it does not: that it involves avoiding the past—leaving it untouched while travelling to a different version of the past in which things proceed differently.