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Scientists characterize a new shape using rubber bands
- bhouston 12y agoIt is also known as the kinked phone cord (back when phones had cords between the base station and the headset): http://i.imgur.com/AS7UI.jpg http://i.imgur.com/AS7UI.jpg :)
- tlarkworthy 12y agoI tried for ages to work out how to unkink them. I never figured it out. I could just move the kink location around but never anhialate it.
- weinzierl 12y agoPhone cords usually end in straight sections, you just move the kink there and it disappears. I think there is no other way.
- shasta 12y agoNo, you can unkink them locally, the opposite of how you introduced them.
- pinko 12y agoWonderful! Could you provide a diagram or explanation? I've never been able to do it reliably, only by random luck.
- shasta 12y agoI don't remember the details, but luckily google knows everything: https://www.youtube.com/watch?v=QeSycf6A7pI https://www.youtube.com/watch?v=QeSycf6A7pI.
- dual 12y agoHere's a hint that helped me understand much of the mystery of phone cord kinks: Notice how in bhouston's image above the coil on the left of the kink has opposite spin as the coil on the right. With this kind of kink there is no solution but to completely re-coil one of the sides.
- sp332 12y agoI think you could "fold" the whole cable back on itself at that point. Instead of unwinding around the axis of the helix, unwind around an axis at a right-angle.
- shasta 12y agoNo, dual is correct. There's no local way to unkink the phone cable in that image. Just notice that the orientation (whether a cord spirals clockwise or counterclockwise as you travel along it) doesn't change in a properly unkinked cord, but the left and right side of the cord in the photograph have opposite orientations. Whatever manipulation you do locally around the kink (even if it involves rotating the whole rest of the cord around rigidly) won't change the orientation of either side. A corollary to this is that the kink in the picture wasn't created locally, and is not the kind of kink you accidentally create. Though you can create a stretch of mis-oriented cord by trying to fix what starts as a local kink, but that requires fiddling with that entire section of cord.
- sp332 12y agoI had to go play with an actual cable for a while, but I see what you mean :)
- rz2k 12y agoChirality refers to the type of twist. While the side of the cord that is inner or outer will stay the same, but if you're looking from one end toward the other, the cord will approach you in a clockwise or counter clockwise circles. Possibly clearer, if you imagine screws[1] that are turned clockwise or counter clockwise to drive into a hole. A kink where the chirality is different on each side is different than a kink where it remains the same on each side. It is possible to create a disturbance where the chirality or twisitng remains the same on both side of the disturbance. Here is a drawing of how to create a disturbance in a telephone cord.[2] And, here is another drawing where two rigid rods have a flexible connector.[3] In these cases the chirality is the same on both sides, so you could just undo the loop. However, in the photograph that was posted, the chirality has changed[1]. So, you would have to straighten and recoil one of the sides to match the other's chirality. [1] Screws http://imgur.com/VbBWL7F http://imgur.com/VbBWL7F [2] Cords http://imgur.com/yJWrAIt http://imgur.com/yJWrAIt [3] Rods http://imgur.com/Qytn8o1 http://imgur.com/Qytn8o1
- sesqu 12y agoOnly if you have two kinks, I think. I'm not sure how people introduce them, but I always had to move them all the way to the end to remove them.
- coldcode 12y agoI never realized when trying to unkink them that it might lead to future nobel prize in chemistry.
- scoot 12y agoThat was my first thought on seeing the second picture, but that's not what's being discussed: 'The shape that Bertoldi and colleagues at SEAS unexpectedly encountered is a hemihelix with _multiple_ “perversions.”' [...] 'there is a critical value of the aspect ratio at which the resulting shape transitions from a helix to a hemihelix with _periodic reversals_ of chirality'. A phone cord may have multiple reversals, but they almost certainly won't be periodic.
- judk 12y agoWow, it seems that the researchers are too young to know that phone cords existed.
- coldtea 12y agoThe resemblance is superficial -- they are discussing something else altogether in TFA.
- jdmitch 12y agoThis also happens with slinkies - I've ruined more good slinkies that way!