It also means that cosmology doesn’t really have a well-defined concept of “now.” Or rather, the “now” you experience is highly specific to you, to where you are and to what you are doing.II What does it mean to say “that supernova is going off now” if we see the light of it now, and we can watch the star explode now, but that light has been traveling for millions of years? The thing we’re watching is essentially fully in the past, but the “now” for that exploded star is unobservable to us, and we won’t receive any knowledge of it for millions of years, which makes it, to us, not “now,” but
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