Spontaneous knotting of an agitated string (2007) | Hacker News Reader

Spontaneous knotting of an agitated string (2007)

ncbi.nlm.nih.gov

71 pointsColinWright23 comments

I can absolutely say that all of this is true. Any set of cables let to stay behind my TV set (say blue ray player, tv, audio system, raspberry and network cables) will spontaneously get entangled in a period of 2 to 3 years. I have repeated that experiments several times with 100% predictable results for years. It also mysteriously attracts tons of dust and not-to-be-seen again small toys. Unbelievable.

I think the dust issue at least has an solid explanation, insofar as most of our electronics have cooling which attracts a lot of dust, much of which falls nearby. The toys... clearly a desperate attempt by either time travelers or extradimensional entities warning us about an invasion of sentient avocados.

I find that nylon wrapped cables are far less knot-prone than rubber; I assume because of the lower friction.

I know this paper! A few years ago I gave a talk about DNA folding titled "DNA topology: nature's headphone cord problem", in which I cited this paper.

The slides are here: https://www.slideshare.net/bonbonsuperbonbon/dna-topology-na...

The title could read "Why headphones get tangled in your pocket".

I found out that when you fold your cables (repeatetly fold it into halves until it is a small enough package) instead of rolling it up that they almost never entangle. I have no idea why that is.

There's a neat way to roll cables, called Roadie Wrap. Best described in video, but basically, you alternate the twist direction while you add each loop to the roll. Every other time the free end goes under the forming loop.

Sailors have been doing this for centuries, likely even millennia.

If you coil a cable around something like your palm or arm, with each revolution there is also a half twist. When unrolling the cable, it doesn't untwist. The result after repeated coiling is a twisted up cable that doesn't lay flat even when wound correctly. The roadie wrap technique removes the twist.

Another technique I've found, and the one I prefer these days, is to coil the cables in the opposite direction when I put them away from when I opened them. If I wrapped the cable around my left arm before, when putting away I use my right arm. This also removes the twist like the roadie wrap. The roadie wrap removes the twist per revolution. This method removes it over the length of the cable.

The way teach this to people is: You have a holding hand and a grabbing hand. Alternate which way your thumb is pointed with your grabbing hand.

I usually grab with my thumb toward the far end of the able first, then the next grab my thumb is toward the coil I am making. Your arm and its available motions sort the rest out.

Ugh please only do this with long cables (that you need to, say, throw across a stage). The nice thing about this wrap style is that the net twist of the cable is 0. The terrible thing is that if the person opening the cable doesn't expect it, they get a big knot and a jolt of frustration.

Not only will a properly wrapped cable (with the natural twist and loop size of the cable) whether straight or over-under unwrap without knotting if unwrapped correctly, it will hugely extend the life of the cable over something like folding them.

Source: I was an intern at a music venue, spent a lot of time wrapping/unwrapping cables.

Rock climbers call this "flaking" a rope. You lay it out on the ground in folds. It is also key to throwing rope, ensuring it doesnt knot mid-air. Imho everyone should learn how to throw a rope. It can so easily make a huge difference in an emergency.

For anyone that doesn't know this trick for extension cords I will write it down here for posterity.

if you have a long extension cord, say 25-100 feet long, do not ever coil it. Instead:

1. find a plastic bucket and cut a small hole in the bottom side of the bucket.

2. Lay the whole extension cord out flat - maybe on a driveway, sidewalk, or road (you only need to do this once)

3. Thread the male end of the extension cord (the side that plugs into the wall) into the top of the bucket and out the hole that you cut.

4. Pull enough of the cord through the hole that you can easily plug it in to the wall (maybe 3-4 ft max).

5. now, "stack" the rest of the cord into the bucket. Make no effort to coil it, don't worry how tangled it looks, it won't actually tangle.

6. for use, you can just pull out the female end and it will come out with no kinks or coils. For storage, stack the whole cord in, and plug the male and female ends together so the female end can't get underneath some of the other folds.

Thank me later!

> if you have a long extension cord, say 25-100 feet long, do not ever coil it.

No, just coil it properly (I haven't checked, but the guys below probably refer to this) and you're not going to have a problem. Some people tend to this correctly by themselves without even noticing it.

Once you discover rope bags (or, cable buckets) it's hard to go back.

People who do technical (arborist) style tree climbing make frequent use of a 1-2mm throwline used as a pilot line to get the climbing rope up into the tree.

It still amazes me to see 200ft of tiny "randomly placed" cord fly out of a basket at high speed without tangles. The stuff is finicky - the tiniest twig will make a huge mess to untangle.

I've started doing this with my headphones and have noticed a difference.

This is what we do with climbing rope, fold it.

Earbud cord control: https://youtu.be/R0rTb2rVsac

That was fun to see, thanks for posting! My masters project gets a mention there and I’d never imagined anyone would have ever read it!

Please tell us more about that!

Hickford et al. in the orginal article. Best summary is probably the below.

https://people.maths.bris.ac.uk/~majge/hjce.06.pdf

We observed knots forming at the ends of the string (chain in this case) vs in the middle.

I can imagine adding 'hook shapes' at the ends of the chain, like headphone ear buds or connectors on a cable in the pocket would increase the likelihood of knotting.

Thanks for the interest.

I train in martial arts, and contrary to the weird cultism about this, I wash my belt like every other part of my uniform.

The result of spin-drying a standard martial arts belt for an hour have often brought a smile to my face from sheer absurdity (5 half knots and a couple exotics), even if (sadly) they are not as impressive as the ones in this paper.

Reminds me of days fishing with my father.

Reply on news.ycombinator.com