Message #3625

From: Joel Karlsson <>
Subject: Re: [MC4D] Physical 4D puzzle achieved
Date: Thu, 09 Feb 2017 09:16:32 +0100

Hi Melinda,

I just wanted to share a thought that I had when looking at the video. If
you were to twist the two outmost layers of 2x2 pieces so that (if the
magnets allow this) from 0:00 in your video, four of the light blue pieces
would move down to the purple face. Wouldn’t this correspond to a legal
2x2x2x2 twist? To me, it seems like that would be a 90-degree twist around
the gray face. This would not solve the problem of getting the reds and
blues to other faces and, in fact, doesn’t add any permutations (I found a
way to undo the twist with 10 twists of the types you showed in the video)
but might work as a shortcut.

Best regards,
Joel Karlsson

PS. The included picture shows such a move around the brown face.[image:
Infogad bild 1]

2017-02-09 6:38 GMT+01:00 Melinda Green
[4D_Cubing] <>:

> Dear cubists,
> I am excited to announce that I’ve been able to implement a working 2^4 in
> the real world! It uses a design I had described
> <>
> a little over a year ago. The key was a clever arrangement of magnets that
> the Mathologer came up with for implementing a 2^3 puzzle. I realized that
> it could be extended to give me a mechanism to support my design. I then
> prototyped it and it works quite well. Here is a quick video I made just
> for you:
> Please do not share this link because it is unpublished and I intend to
> delete and replace it with a proper video. It is mainly meant for getting
> your feedback and advice. Please reply here, or privately to
> if you’re shy. Feel free to comment on all
> aspects of the video, and not just on the mathematics. For instance, feel
> free to comment on the video and audio quality, or anything else that
> strikes you.
> Many of us have dreamed about such a puzzle for a long time and it’s
> become something of a holy grail. It’s always seemed almost impossible to
> create any sort of 4D puzzle in the real world, but there was never any
> clear reason why it couldn’t be done. The real holy grail would be a
> physical 3^4, so maybe this is just the baby grail. Of course maybe this
> design can be extended to implement a 3^4. What do you think?
> Happy puzzling!
> -Melinda