The Sieve of Eratosthenes

What with pressing the wrong button on the last post and delivering it incomplete and going away to London for a couple of days tomorrow, I’d better nip in and fill this window of opportunity with my latest excitement concerning prime numbers. It was Stan who introduced me to the idea of the Sieve of Eratosthenes on a walk and I came home and tried it out and it worked-up to 100 anyway; I didn’t have time to take it any higher and anyway the excitement was giving me a headache.

Circle the remaining numbers and you have the primes up to 100. Why don’t they teach maths through wonder in schools? For notice it is the prime numbers 2,3,5 and 7 that you use to eradicate all non primes 1-100. Isn’t that amazing?

What you do is map out a grid 1-10 ten times giving you numbers 1-100. Starting with 2 you cross out every second number, then go to three and cross out every third number. Ditto 5 and every fifth number. Ditto seven and every seventh number.

Can you invert the previous two paragraphs because something strange is happening to my editing system and I haven’t time to retype? Thank you.

I’ve always found the primes very soothing numbers and I’m not alone in this. Maybe Kitty the counsellor was right when she suggested that I had a toe on the high functioning end of the autistic spectrum. Certainly I get very itchy in supermarkets, hate doing anything under fluorescent lights and suffer sensory overload when out with too many people in noisy restaurants.

In fact the real world is often too much for me and then I move into the world of numbers which I find safe and steady. I feel happy finding that there is an incomprehensible but nevertheless evident mesh holding it all in place and that numbers map that mesh.

I once wrote a book about the mysterious covalency of water and the fact that it holds the living world together. I called the book Holding Together, a title that referred to the 8th trigram of the I Ching. My editor didn’t like the title and it was changed but as the book couldn’t find a publisher it languishes in the second drawer of my desk, along with the others, while I get on exploring further the underpinnings of nature. The point I’m making here is that the primes indicate something really important about the way the world is made. They map a code. As Galileo said ‘the book of nature is written in mathematics’ and the fact that mathematics is not something created by the human mind is deeply comforting to me. There is a scaffold on which the prime numbers are built. It is 1+2+3=6. This underpins the grammar of form in some way and both bees and quarks dance the pattern of the language it forms. Wow


2 responses to “The Sieve of Eratosthenes

  1. Bees and quarks dancing a universal foxtrot, great post Allie!


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