 The fact that, in relativistic physics, elapsed time is relative to worldlines suggests a new type of bifurcated supertask. The idea is simple. (A version of the following idea is given in Pitowsky 1990.) Two people, Alice and Bob, meet at an event \(p\) (the start of the supertask). Alice then follows a worldline with a finite elapsed time which ends at a given event \(q\) (the end of the supertask). On the other hand, Bob goes another way; he follows a worldline with an infinite elapsed time. Bob can use this infinite elapsed time to carry out a computation which need not halt after finitely many steps. Bob might check all possible counterexamples to Goldbach’s conjecture, for example. (Goldbach’s conjecture is the statement that every even integer n which is greater than 2 can be expressed as the sum of two primes. It is presently unknown whether the conjecture is true. One could settle it by sequentially checking to see if each instantiated statement is true for \(n=4\), \(n=6\), \(n=8\), \(n=10\), and so on.) If the computation halts, then Bob sends a signal to Alice at \(q\) saying as much. If the computation fails to halt, no such signal is sent. The upshot is that Alice, after a finite amount of elapsed time, knows the result of the potentially infinite computation at \(q\). 