In the latest edition of “What If” by xkcd, Randall Munroe answers a reader who asks whether one person could walk the entirety of New York City (including the space inside apartments) in a single lifetime. As is his custom, Munroe’s answer is not quite so straight forward as the question might suggest.
Imagine that each person lives alone in a square room measuring 10 meters by 10 meters, which is about the size of a typical two-bedroom apartment. Furthermore, let’s assume that everyone’s apartment is on the ground floor with at least one side facing a street. In that case, at a walking speed of 2.5 mph, it would take only 2.4 years to walk past every apartment—which Wolfram|Alpha helpfully points out is roughly 1.4 elephant gestation periods.
image via xkcd