Tuesday, 7 July 2009

It's a long way

I thought I'd brush up on my statistics before I get going on Sunday. Britain's coastline is longer than one thinks. For such a small country, it does itself proud.

Here are some interesting random stats on coastlines of the world, taken from Wikipedia .

Britain’s coastline is 12 429kms long. It's got the 13th longest coastline in the world (!!), beating countries like Italy, Brazil and Chile. The reason for this is that Britain has so many islands and peninsulas. Because I'm driving around the mainland of Britain only, and because the roads don't follow the coast exactly, my trip will be "only" about 7,500kms, which is still more than the entire coastlines of countries like Chile and India.

The longest coastline in the world belongs to Canada at a truly massive 202 000kms. Crikey. That's the equivalent of driving five times around the equator. The two smallest coastlines belong to Gibraltar with 12kms, and Monaco, with a paltry 4kms. Here are the top 20:

1. Canada 202,080kms

2. Indonesia 54,716kms

3. Greenland 44,087kms

4. Russia 37,653kms

5. Phillipines 36,289kms

6. Japan 29,751kms

7. Australia 25,760kms

8. Norway 25,148kms

9. United States 19,924kms

10. New Zealand 15,134kms

11. China 14,500kms

12. Greece 13,676kms

13. UK 12,429kms

14. Mexico 9,330kms

15. Italy 7,600kms

16. Brazil 7,491kms

17. Denmark 7,314kms

18. Turkey 7,200kms

19. India 7,000kms

20. Chile 6,435kms

My home country of South Africa is down at number 41 with 2,798kms.

What’s really interesting about these figures is that they are extremely variable, and behave like a “fractal”, as geeks call it. So the length of a coastline depends on the scale you measure it with. The smaller the measurement scale, the longer the coastline that you're trying to measure. For example, if one uses a scale of 1mm, the length of a coast will be much longer than if one uses a scale of 1km. Reason being that if you measure every single millimetre along the coast, and add up all those millimetres, the length will be much longer than if you measured, say, in 1km chunks. And the more “convoluted” the coast (the more bays, inlets etc), the longer it will be. If you used a 1mm scale, you'll end up measuring every tiny nook and cranny, whereas if you used a 1km scale, you wouldn't be able to.

The scale for measuring the list of figures above is not known, but if you used a really small scale, these figures could be much larger than they are. However, whichever scale is used, the order of countries wouldn’t change.

If I'm not mistaken (which I could well be, so correct me if I am), the same principle can be illustrated in a slightly different way with the following example, something I remembered from school (one of the few things!). If you stand a metre from a wall, and halve the distance, moving closer to the wall, you’ll be half a metre away. Then keep halving the distance to the wall, and keep moving closer. In theory, you’ll never actually reach the wall, because you can halve the distance an infinite amount of times. The same applies to measuring the length of a coastline. There’s always a smaller scale that one can use to measure.

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