 In Newtonian physics, time passes at the same rate for all observers. If Alice and Bob are both present at Alice’s 20th and 21st birthday parties, both people will experience an elapsed time of one year between the two events. (This is true no matter what Alice or Bob do or where Alice and Bob go in between the two events.) Things aren’t so simple in relativistic physics. Elapsed time between events is relative to the path through spacetime a person takes between them. It turns out that this fact opens up the possibility of a new type of supertask. Let’s investigate this possibility in a bit more detail.