Why it's impossible to measure England's coastline |
Why it's impossible to measure England's coastline
A new hiking trail will soon allow travellers to walk around England's entire coast – but a strange paradox means no one knows exactly how long it is.
Last month, King Charles III inaugurated a new hiking path that will soon stretch around the entire coast of England. The project is roughly 80% complete, and when it fully opens later this year, the King Charles III England Coast Path will become the longest managed coastal walking path in the world.
The 2,689-mile-long (4,327km) ramble connects the granite cliffs of Cornwall with the rolling sand dunes of Northumberland and East Sussex's iconic white chalk cliffs, allowing travellers to explore England's extensive shoreline step by step.
But while the length of the newly designed path is easily measurable, the coastline that it follows is not. England's coast is often measured as part of the UK's, but look up how long that is and you'll get wildly different answers from various reputable organisations. The CIA World Factbook lists the UK's coastline as 7,723 miles (12,429km), while The World Resources Institute measures it at 12,251 miles (19,716km) – a discrepancy of more than 4,500 miles (7,242km).
"The thing is, no one really knows exactly how long England's coastline is, or the United Kingdom's or most coastlines around the world, for that matter," said Victoria Braswell, a researcher and member of the Royal Geographical Society. "It's all in how you measure it."
Search for a larger territory like the United States and this disparity grows even further, from 12,380 miles (19,924km), according to the CIA World Factbook; to 84,000 miles (135,185km), according to the US Army Corps of Engineers; to an astonishing 95,471 miles (153,646km), according to the National Oceanic and Atmospheric Administration (Noaa), the federal agency responsible for mapping the US's coastline.
One reason why these measurements vary so greatly, and why none is technically wrong, goes back to a curious discovery made by a British pacifist who was trying to understand war – and it's pitted nations against each other.
The coastline paradox
In 1921, a Quaker mathematician and physicist named Lewis Fry Richardson wondered whether nations with longer shared borders were more likely to go to war. During his investigations, he noticed something peculiar: Spain reported its border with Portugal as 987km (613 miles), while Portugal measured it as 1,214km (754 miles). Belgium and the Netherlands also had a 69km (43 mile) disparity, and countries across the continent had similar disagreements.
Since these measurements were vitally important for a nation's sovereignty, Richardson wondered why the differences were so widespread. At the time, most countries measured their borders and coastlines by examining a map and placing rulers of equal length along their boundaries, so that one end of the ruler was always touching the other. But since almost no borders or coastlines are perfectly straight, Richardson realised that the smaller the ruler, the more curves it captured – and the longer the total measurement became.
This phenomenon became known as the coastline paradox, and it applies to virtually all borders, boundaries and coastlines with especially jagged, twisting lines – like England's.
"Let me show you what this paradox looks like," said Danny Hyam, a senior geospatial consultant for the Ordnance Survey, Great Britain's national mapping agency.
"This is Britain's coastline at a........