Rubik Cube.
Erno Rubik born July 13, 1944, Budapest, inventor of Rubik's Cube, a popular puzzle.
Rubik's Cube consists of 26 small cubes that rotate on a central axis; nine coloured cube faces, in three rows of three each, form each side of the cube. When the cube is twisted out of its original arrangement, the player must then return it to the original configuration, one among 43 quintillion possible ones.
The son of a poet mother and a glider-manufacturer father, Rubik studied sculpture at the Technical University in Budapest and architecture at the Academy of Applied Arts and Design, also in Budapest. While a professor of design at the academy, he pursued his hobby of building geometric models. One of these was a prototype of his cube, made of 27 wooden blocks; it took Rubik a month to solve the problem of the cube.
It proved a useful tool for teaching algebraic group theory, and in late 1977 Konsumex, Hungary's state trading company, began marketing it. By 1980 Rubik's Cube was marketed throughout the world, and over 100 million authorized units, with an estimated 50 million unauthorized imitations, were sold, mostly during its subsequent three years of popularity. Approximately 50 books were published describing how to solve the puzzle of Rubik's Cube. Following his cube's popularity, Rubik opened a studio to develop designs in 1984; among its products was another popular puzzle toy, Rubik's Magic.
A standard Rubik's cube measures 2¼ inches on each side. The puzzle consists of twenty-six unique miniature cubes. Each of these includes a concealed inward extension that interlocks with the other cubes, while permitting them to move to different locations.
However, the centre cube of each of the six faces is merely a single square façade; all six are affixed to the core mechanism. These provide structure for the other pieces to fit into and rotate around. So there are twenty-one pieces: a single core piece consisting of three intersecting axes holding the six centre squares in place but letting them rotate, and twenty smaller plastic pieces which fit into it to form the assembled puzzle.
Each of the six center pieces pivots on a screw held by the center piece. A spring between each screw head and its corresponding piece tensions the piece inward, so that collectively, the whole assembly remains compact, but can still be easily manipulated.
The Cube can be taken apart without much difficulty, typically by rotating the top layer by 45° and then prying one of its edge cubes away from the other two layers. Consequently it is a simple process to "solve" a Cube by taking it apart and reassembling it in a solved state.
There are twelve edge pieces which show two colored sides each, and eight corner pieces which show three colors. Each piece shows a unique color combination, but not all combinations are present for example, if red and orange are on opposite sides of the solved Cube, there is no edge piece with both red and orange sides. The location of these cubes relative to one another can be altered by twisting an outer third of the Cube 90°, 180° or 270°, but the location of the colored sides relative to one another in the completed state of the puzzle cannot be altered: it is fixed by the relative positions of the centre squares and the distribution of color. However, Cubes with alternative color arrangements also exist; for example, they might have the yellow face opposite the green, and the blue face opposite the white with red and orange opposite faces remaining unchanged..
Cubes could be colored in such a way as to emphasize the corners or edges, rather than the faces as the standard coloring does; but neither of these alternative colorings has ever become popular.
