

Scientists characterize a new shape using rubber bands - ABS
http://www.seas.harvard.edu/news/2014/04/scientists-characterize-new-shape-using-rubber-bands

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bhouston
It 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)

:)

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tlarkworthy
I 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.

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weinzierl
Phone cords usually end in straight sections, you just move the kink there and
it disappears. I think there is no other way.

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shasta
No, you can unkink them locally, the opposite of how you introduced them.

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pinko
Wonderful! Could you provide a diagram or explanation? I've never been able to
do it reliably, only by random luck.

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dual
Here'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.

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sp332
I 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.

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shasta
No, 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.

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sp332
I had to go play with an actual cable for a while, but I see what you mean :)

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jdmitch
This also happens with slinkies - I've ruined more good slinkies that way!

