Melinda’s 2x2x2x2

Melinda’s 2x2x2x2

4D Shape: Tesseract

Physical Shape: Rectangular prism

Pieces: 16 4c

Magnets: 384

Permutations: \(3.3*10^{27}\)

See Melinda’s 2x2x2x2 website for her project overview.

History

Invention

Many hypercubers, including Melinda Green (one of the developers of MC4D) wanted to create a physical 3⁴, but sadly it just seemed too complicated. Eventually, she decided to focus on the 2⁴ due to its simplicity of only having 16 4c pieces.

Throughout 2013 and 2014, Melinda was in contact with Oskar van Deventer, and together they tried to think of any possible mechanism for a physical 2⁴. Originally they were determined to find a good mechanism that didn’t have to rely on magnets, but after several failed attempts a magnetic mechanism was the only solution. In 2017, Melinda built the first prototype and shared an unlisted YouTube video showing it off to the mailing list members.

A few months later, Melinda built a 2nd prototype using 3D printing from a company called Shapeways (which just so happened to offer 8 colors, 6 of them being standard Rubik’s Cube colors, plus pink and purple (this is where the standard 4D colour scheme comes from)).

Popularization

Professor Erno Rubik inspecting a physical 2⁴ at G4G 2018

At the Gathering For Gardner conference of 2018, Roice Nelson got to show his physical 2⁴ to Erno Rubik. It was reported that his only comment was something along the lines of “none of the derivative puzzles matter and that only his original invention is important”.

Also in 2018, the YouCuber CanChrisSolve? made a series of videos where he solved the physical 2⁴, which have now amassed over 100,000 views combined! A month later, a Spanish YouCuber called TheMaoiSha made a video explaining the physical 2⁴ which now sits at over 800,000 views, exposing the world of hypercubing to more and more people.

Because of all this recognition, many new people bought the puzzle, but it was still pretty expensive because of the costs of 3d printing and the labor of manual assembly. Eventually Melinda moved away from 3D printing in favour of injection molding, which greatly reduced the price while increasing the quality dramatically.

Where can I buy one?

Read this section of Melinda’s website.

How Does it Work?

Animations showing how the virtual and physical 2⁴ transform into each other

Each twist and rotation on the virtual 2⁴ is possible to do on the physical puzzle, albeit with certain moves requiring some extra setup. See the canonical moves page for a more detailed explanation.

Also see Melinda’s video on the official canonical moves.

In December of 2017, Melinda made a video fully explaining the puzzle, including its canonical moves, scrambling, and more.