The Rubik's Revenge, also known as the 4x4, is the sequel cube to the Rubik's Cube. The idea of the Rubik's Revenge is that it has more combinations and ways to solve, which also makes it harder. Although it has 16 pieces on each side, it is solved with a very similar method to the 3x3x3.
The unicode character U+25A6 (▦) resembles this cube.
The Rubik's Revenge was patented by Péter Sebestény on December 20th 1983. It was orriginally going to be named the Péter Sebestény Cube, until a last minute change was made to attract fans of the original Rubik's Cube.
Since the Rubik's Revenge has 16 cubelets on one side, it is built differently than the 3x3x3. Unlike a 3x3x3 Cube, the RR has 4 center cubelets on each side, and 12 edge cubelets. The 3x3x3 is built on a cross like object, with the center pieces fixed into place and the edges interlocking with eachother, but the RR is built on a sphericle body. The sphere that the RR is built on has 8 pieces lifted approximantly 1/4" off of the sphere. The 8 pieces can be loosened or tightened with a screwdriver. The center cubelets are snapped in where 4 pieces make one point. The edge cubelets then interlock with the center pices from 2 sides. The corner cubelets fit between 2 sets of edge cubelets. This design makes it harder to speedcube. To speedcube the RR, people make their own custom built Rubik's Cubes or buy higher quality 4x4x4's.
Solving the Rubik's RevengeEdit
The Rubik's Revenge can be solved with formulas very similar to the 3x3x3 cube. The only two problems are that unlike the 3x3x3 cube, this cube has the center cubie is split into 4 smaller cubies, and 12 edge pieces split into 2 smaller cubies each. To solve the cube, you must solve the center cubies, by making a 2x2 square on the center of each side of the cube, each representing the color of that side in it's solved state. You must then solve the edge pairs by placing each color pair on one edge of the cube together. After solving those, you can solve the cube with any method used on the 3X3X3 cube. The final step is to fix what is called a parity. The 4x4x4 can have two possible problems not found on the 3x3x3. The first is two edge pieces reversed on one edge, resulting in the colors for that edge not matching the rest of the cubies on either face. The second is two edge pairs, known as dedges, being flipped with each other. Two more algorithms are required to fix these parities.
The official world records for the Rubik's Revenge single (21.97 seconds) and average (26.03 seconds) are both held by Sebastian Weyer of Germany.