A while ago I attended a seminar where someone used the fourth dimension to calculate molecular interactions. He explained that, contrary to popular belief, the fourth dimension was not time. So what is the fourth dimension? Here is a website that explains it all using very basic drawings of Fred and Bob, who live in the second and third dimension, respectively.
Here’s another explanation on the blog Lord of Net:
“An old story tells us how to keep our money safe from robber that exists only in two dimensions (sheet of paper): simply just put it in square safe. 2D robber won’t be able to reach it… but if another 3D cruck wanted the gold, he would simply take the gold out of the square not even touching the safe walls. On the other hand, to keep gold out of reach from 3D robber you would need a cube safebox with walls on all 6 sides…now the gold is secure.. but imagine another robber bursting from 4th dimension just to steal our gold!”
Once you understand, you can give this four dimensional Rubik’s cube a try…