MSCS Graduate Student Seminar
Fall 2000
September 8
SPEAKER: Mark Ronan
TITLE: Magic with a wineglass explained using topology and group theory
ABSTRACT: Take an object, a wineglass for example, and rotate it by 360
degrees. Imagine it attached by invisible cords to the corners of the room.
After the rotation these cords will be twisted together although the
wineglass itself will be back in its original state. The cords cannot be
untwisted, but if you rotate the wineglass by a further 360 degrees, making
720 degrees in total, then the cords, which are now even more twisted
together, can be returned to their original untwisted state without
rotating the wineglass at all. This strange phenomenon is related to some
elementary aspects of topology and Lie groups. There is no need to know
anything about Lie groups or topology beforehand.