The Coastline Paradox

Pick a coastline. Any coastline. The one nearest to where you live, or one you have visited, or the edge of an island you have only seen on a map. Now answer a simple question: how long is it? You could look this up. If you chose Britain, most references will give you something around twelve thousand five hundred kilometres. That seems definitive. But that number is not what it pretends to be, and the reason it fails reveals something unsettling about measurement itself. Start with a ruler one hundred kilometres long. Lay it along the coast, end to end, connecting the broadest points. You will cut across every bay, skip every inlet, miss every peninsula. You get a number. It is small. Now swap for a ruler ten kilometres long. This one follows the coast more closely. It dips into estuaries, traces headlands, catches the curve of harbours the larger ruler jumped over. Your total is longer than before. Not slightly longer — substantially longer. Try a one-kilometre ruler. Now you are tracing individual coves. Rocky outcrops.