The idea that a well-defined now exists throughout the universe is an illusion, an illegitimate extrapolation of our own experience.29 It is like the point where the rainbow touches the forest. We think that we can see it—but if we go to look for it, it isn’t there. If I were to ask, “Are these two stones at the same height?” in interplanetary space, the correct answer would be: “It’s a question that doesn’t make sense, because there isn’t a single notion of ‘same height’ throughout the universe.” If I ask whether two events—one on Earth and the other on Proxima b—are happening “at the same
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