 Partisans of a global now in Minkowski spacetime face, according to Dieks, a dilemma. “If we are not going to refer to the actual material worldlines in the universe, but only to the spacetime structure itself, we have insufficient resources to fix a unique set of global nows. If we do attempt to rely on the actual material worldlines, however, we will not succeed in defining global nows at all” (Dieks, p. 7).