Puzzlemaker Wyna Liu drew inspiration for this issue’s The Stack from Caltech’s annual Pumpkin Drop. Since 1972, Caltech students have celebrated Halloween with delightful destruction—smashing liquid-nitrogen-frozen pumpkins from the tallest building on campus at the stroke of midnight. In recent years, the event has attracted large crowds of spectators, who watch safely from a distance, as pumpkin debris explodes into the night of tricks and treats.
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