A sphere has two sides. However, there are one-sided surfaces.
Posted: Thu Aug 26, 2004 7:56 pm
Möbius Strip
A sphere has two sides. A bug can be trapped inside a spherical shape or crawl on its visible surface.
A sheet of paper also has two sides.
The first one-sided surface was discovered by A. F. Möbius (1790-1868) and bears his name: Möbius strip. Sometimes it's alternatively called a Möbius band. (Actually, the surface was described independently and earlier by a couple of months by another German mathematician J. B. Listing.)
The strip was immortalized by M. C. Escher (1898-1972).
Attached files
A sphere has two sides. A bug can be trapped inside a spherical shape or crawl on its visible surface.
A sheet of paper also has two sides.
The first one-sided surface was discovered by A. F. Möbius (1790-1868) and bears his name: Möbius strip. Sometimes it's alternatively called a Möbius band. (Actually, the surface was described independently and earlier by a couple of months by another German mathematician J. B. Listing.)
The strip was immortalized by M. C. Escher (1898-1972).
Attached files