The 360-720 difference can be illustrated quite dramatically by making a square frame with (as I recall) four strings attached which go through holes in a small block inside the frame. I realize that details here are sparse, but I could probably make a crude one if offered enough money (say twelve million dollars). Steve Gray ----- Original Message ----- From: "Thane Plambeck" <thane@best.com> To: <math-fun@mailman.xmission.com> Sent: Sunday, April 04, 2004 11:47 AM Subject: [math-fun] dirac scissors trick + balinese cup trick
(This is the same thing that says you can hold a full cup of coffee in one hand, and without letting go or spilling, turn it around twice and get back in the same position. However, if you turn it around just once, your arm will be in a different, probably awkward, position.)
I read that Dirac illustrated this fact, that a 360 degree rotation isn't the same as a 720 degree one, using strings tied to a pair of scissors, right?
My question: where/when did he do it?
Thane Plambeck 650 321 4884 office 650 323 4928 fax http://www.plambeck.org
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