Every Rubik's Cube is Solvable in 20 Moves or Less

Perhaps for 3x3x3 cubes but there are also 4x4x4 and 5x5x5 cubes which I imagine have more possibilities.

Douglas Hofstadter's Metamagical Themas articles ~1980 on Rubik's Cube were classics. He didn't give away the solution, but he did give many ideas for finding one. He also gave a quick argument that "God's Algorithm" might not be much more than 18 moves. Before long, algorithms of 50 or fewer moves were known.

About that time, I was working on a fish freezing ship that offloaded sockeye to Japanese freighters. The Japanese guys were struggling with The Cube with no success. One of our crew got them to lend it to me. By that time I had a crude 3-minute routine of something like 150 moves. There was enjoyable dismay when I tossed back the solved cube.