A genie (as the story is told) lights a candle at a minute before midnight. After half of the minute has passed, the genie extinguishes the flame. Fifteen seconds later, she relights the candle, and again, halfway to midnight, she puts the flame out. This continues as midnight approaches, the time always divided in two, the flame soon leaping up and vanishing faster than we can see.

Now the genie asks you, “At midnight, will the flame be lit or out?”

Leaving aside the issue of when this question is asked, you are still left with some bewildering possibilities. The candle is neither lit nor out? The candle is both lit and out? We never get to midnight?

But of course we get to midnight; there has yet to be a midnight that we have failed to get to. There is a midnight right now that is approaching. Or are we approaching it? Which is staying still? Which is the arrow and which is the target?

One thing we have learned during the story of physics (in 1632) is that nothing sits still; you may see a passenger on a boat and a bird perched on the mast over her head as ‘moving’, but from their joint point of view, you are the one who is moving. Later in the story (in 1905), we learned that one observer may experience time as running more slowly than does another observer.