Scientists Untangle Knots
By Hayley Birch
So you've hauled yourself out of bed at an unearthly hour, squeezed into a new, eyepoppingly skintight gym kit, battled against gale force winds and somehow wound up standing on a treadmill at 7am. What now? Oh yes, music.It's now, though, that your realise your headphones have worked themselves into some sort of unfathomable knot. You can't understand it. They can't have been knocking around the bottom of your bag any longer than a day. It takes several minutes of frantic untangling before you finally stuff them in your ears. You'll have cut your run short now. Shame.
But why is it that headphones - and, for that matter, sewing threads, necklaces, extension leads and fairy lights - are capable of forming such inexplicably complicated knots when left unsupervised? Physicists at the University of California, San Diego, have been trying their hardest sort out this mess.
You've heard of string theory. Well, this is knot theory. Douglas Smith and his team are studying how knots form in string, something scientists have devoted relatively little time to until now. "In our experiments, we produced thousands of different knots, used mathematical knot theory to analyse them, and then developed a simple physics model to explain our findings,” says Smith.Different lengths of string are dropped into a plastic box, which is spun, using a computer controlled motor, for varying lengths of time. A computer program analyses the knots that form and decides how complicated they are.
Unsurprisingly, it turns out that longer strings form more complex tangles. And a smaller box (or space at the bottom of your gym bag) means there's less room for the string to tumble about, decreasing the chance that an end will fall through a coil to form a knot. These coils, say the researchers, are key to knot formation in confined spaces.
But it's not just your listening time that's affected by this theory; there's a whole world tying itself in knots out there, Smith explains. "Knots often form in DNA, which is a long string-like molecule. Cells have enzymes that undo the knots by cutting the DNA strands so that they can pass through each other. Certain anti-cancer drugs stop tumor cells from dividing by blocking the unknotting of DNA." There's something to think about whilst you're de-knotting your iPod.
Something else to think about:
- Hey? - What the hell are fractals?
- Experiments - Getting DNA out of a banana
- Sexy - Our Hot Scientists
- Scary - Maths hurts, stops brain
Image: Rodolfo Clix
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