The 15 puzzle - solving the unsolvable 19th century Rubik's square

TL;DR

The 15 puzzle, popular in the 19th century, was believed to be unsolvable until new methods were discovered.

Transcript

oh you're probably all familiar with this puzzle here so we've got a picture distributed on 15 tiles and we've got an empty square and this is empty square can push those tiles around in a box and if you just persistent enough what you'll be able to do is reconstruct the picture like so this puzzle here is actually what I'm going to talk about toda... Read More

Key Insights

• 👶 The 15 puzzle was a popular craze in the 19th century, but remained unsolved until new methods were discovered.
• 🥺 The puzzle's perceived unsolvability led to offers of prizes, including sets of false teeth worth $25 and $100.
• 🉐 The Rubik's Cube, which gained popularity in the 1980s, is solvable using various techniques.
• 🧩 Understanding the concept of even permutations and special swaps of pieces provides insights into the solvability of puzzles.

Questions & Answers

Q: Why was the 15 puzzle unable to be solved by anyone during the 19th century craze?

The puzzle's difficulty lied in a specific swap of tiles, which made it seemingly unsolvable. Even those who claimed to solve it couldn't provide verifiable solutions.

Q: How did the 15 puzzle compare to the Rubik's Cube?

Both puzzles gained immense popularity in their respective eras. The Rubik's Cube, however, has proven to be solvable using various methods, unlike the unsolvable 15 puzzle.

Q: What was the significance of the number of moves in attempting to solve the puzzle?

Through observations, it was determined that a solution to the 15 puzzle required an even number of moves. This provided a clue towards its unsolvability.

Q: How did the introduction of round pieces change the solvability of the puzzle?

By introducing round pieces, an additional degree of freedom was added to the puzzle, making it solvable. Different twists and turns allowed for successful solutions.

Summary & Key Takeaways

• The 15 puzzle consists of tiles numbered from 1 to 15 and an empty square, and was a craze in the 19th century.

• Despite many attempts, no one could solve the puzzle, leading to offers of prizes for a solution.

• A new method involving special swaps of pieces and the concept of even permutations was discovered to solve the unsolvable puzzle.