Learning about 4D just got a whole lot more awesome.
You can play 4D Toys on iOS or in VR, and it seriously has to be one of the coolest things I've ever seen.
The whole idea is that you are given a box "filled with mysterious toys from the fourth dimension". This video explains it far better than I can:
"In this case the 4D is not time but a 4th dimension of space that works just like the first three dimensions we are familiar with," says developer mtb design works. "If you count time these toys are 5D."
See, the rules of how objects bounce, slide and roll around can be generalised to any number of dimensions - and this unique toy lets you experience what that would look like.
There are over 100 interactive scenes to play with, and a bonus 2D/3D "Flatland" Interactive Explanation that teaches by analogy about a fourth spatial dimension. The 4D+Time Physics Engine uses new mathematics created just for this project.