Open Science: Explaining Spontaneous Knotting
Posted on March 4, 2009 Comments (0)
Shedding light on why long strands tend to become knotted
Which, it turns out, it basically is. In October, two UCSD researchers published the first physical explanation of why knots seem to form magically, not just in strands of Christmas lights, but in pretty much anything stringy, from garden hoses to iPod earbud cords to DNA.
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“We’re not mathematicians,” Smith said. “We’re physicists. Physicists do experiments.”
UCSD researchers constructed a knot probability machine that involved placing a single length of string in a plastic box, sealing it, then rotating the box at a set speed for a brief period of time.
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The experiment involved placing a single length of floppy string into a plastic box, sealing it, then rotating the box at a set speed for a brief time. The researchers did this 3,415 times, sometimes changing variables such as box size and string length.
Open access research paper: Spontaneous knotting of an agitated string by Dorian M. Raymer and Douglas E. Smith.
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As L [length] was increased from 0.46 to 1.5 m, P increased sharply. However, as L was increased from 1.5 to 6 m, P saturated at 50%.
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Tripling the agitation time caused a substantial increase in P, indicating that the knotting is kinetically limited. Decreasing the rotation rate by 3-fold while keeping the same number of rotations caused little change in P.
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We also did measurements with a stiffer string and observed a probability of finding a knot would approach 100% with an substantial drop in P.
Yet another interesting case of scientists explaining the world around us (and the value of open science).
Related: Toward a More Open Scientific Culture – Electron Filmed for the First Time – Saving Fermilab – Scientists and Engineers in Congress
Categories: Open Access, Research, Science, Students
Tags: cool, experiment, open access paper, physics, science explained, science facts, university research
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