Britney Gallivan
From Wikipedia, the free encyclopedia
 |
This article's introduction section may not adequately summarize its contents. To comply with Wikipedia's lead section guidelines, please consider expanding the lead to provide an accessible overview of the article's key points. (June 2009) |
 |
A significant amount of this biography article's content may actually relate to a subject other than the person's life. See coatrack articles and content forking for details. |
Britney Gallivan (born c. 1986) of Pomona, California is best known for determining the maximum number of times which paper or other non-compressible materials can be folded.
Contents |
[edit] 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 number of times any piece of paper could only be folded in half was limited to eight times. She folded a very long sheet of toilet paper in half 12 times, posing at the 11th fold to take pictures. She knew that instead of folding in half every other direction the best way to get 12 folds would be to fold in the same direction, using a very long sheet of paper. A special kind of $85 toilet paper met her length and width requirement. Not only did she provide the empirical proof, but she also derived an equation that yielded the width of paper, W, needed in order to fold a piece of paper of thickness t any n number of times.
Gallivan's story was mentioned in the episode Identity Crisis [1] of Numb3rs on CBS in 2005, an episode of MythBusters [2] on The Discovery Channel in 2007, and in an episode 3 of the F series of QI.
In 2007 Gallivan graduated from UC Berkeley with a degree in Environmental Science from the College of Natural Resources.
[edit] 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 and n represents the number of folds desired.
These equations indicate two things: that in order to fold anything in half, it must be π times longer than its thickness; and that depending on how something is folded, the amount its length decreases with each fold differs.
[edit] See also
[edit] References
[edit] External links
- Historical Society of Pomona Valley Page
- Folding at MathWorld
- Independent verification of equation at Caltech
- Entry A076024 for the folding function at the On-Line Encyclopedia of Integer Sequences
