The amazing thing about DNA is that even though it is incredibly long, it never seems to "knot". I guess that if it ever does get knotted, the whole cell commits suicide (or at least tries to -- perhaps a source of cancer?) Some relatively small bacterial and mitochondrial DNA are circular (except when being copied), which probably aids in keeping them from knotting. At 04:47 PM 12/24/2012, Fred lunnon wrote:
On 12/25/12, Bill Gosper <billgosper@gmail.com> wrote:
Awful thought: What is the expected time at which a 3D random walk first becomes "knotted"? (W.r.t. pulling on the ends.)
Bearing in mind that the ends may in general lie deep within the convex hull of the walk, perhaps this question requires rather more careful definition ... WFL