Britney Gallivan having made the 11th fold
Britney Crystal Gallivan (born 1985) of
Pomona, California, is best known for determining the maximum number of times that paper or other materials can be folded in half.
[]Biography
In January 2002, while a junior in high school, Gallivan demonstrated that a single piece of
toilet paper 4000 ft (1200 m) in length can be folded in half twelve times. This was contrary to the popular conception that the maximum number of times any piece of paper could be folded in half was seven. She calculated that, instead of folding in half every other direction, the least volume of paper to get 12 folds would be to fold in the same direction, using a very long sheet of paper. A special kind of $85-per-roll toilet paper in a set of six met her length requirement. Not only did she provide the empirical proof, but she also derived an equation that yielded the width of paper or length of paper necessary to fold a piece of paper of thickness
t any
n number of times.
In 2007, Gallivan graduated from
UC Berkeley with a degree in Environmental Science from the College of Natural Resources.
[]Paper folding theorem
An upper bound and a close approximation of the actual paper width needed for alternate-direction folding is
For single-direction folding (using a long strip of paper), the exact required strip length L is
where t represents the thickness of the material to be folded, W is the width of a square piece of paper, L is the length of a paper piece to be folded in only one direction and n represents the number of folds desired.
These equations show that, in order to fold anything in half, it must be
times longer than its thickness, and that, depending on how something is folded, the amount its length decreases with each fold differs.
[]In popular culture
