h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Have you ever read "A Wrinkle in Time" by Madeline L'Engle? Great fantasy and it attempts to describe tesseracts in the simplest form possible (first thing that came to mind really...)

Anyway, great article and very informative!

My first encounter with four dimensional objects was an Open University programme (complete with bearded presenter in a scruffy pullover ) about the Klein Bottle. I believe there is an entry somewhere in The Guide about the KB. Having the benefit of animated graphics made it very easy to follow the progression from a Moebius strip to a Klein Bottle, and understand the dynamics. Being a bear of very little mathematical brain (although quite good at spatial awareness - I used to be a removal man, and one of the friends who helped me out from time to time once said that I packed a vanful of furniture and boxes so well that if you picked it up and turned it upside down, none of the contents would move )though, I'm having a lot more trouble getting my head around the ins and outs and ups and downs and arounds and throughs of a tesseract, even though the entry is so well written. Two thumbs up!
If you want to see some more h2g2 ascii art btw, check out the personal space of Minesweep Goddess aka the Mad Forum Artist, and some of the conversations she's been involved in, especially "Forum Art Here", and her posts in The Procrastinator's Society conversations

I guess the artists blew their minds trying to draw a piccie for it...

Yes: great entry!

Although I've read A Wrinkle in Time (twice), I somehow managed to miss the explination of a tesseract both times... I'll have to go back, and look again. It doesn't help that I was a bit too young to be understanding that type of stuff when I tried to read it before. I did become aquainted with the concept of Tesseracts during the sci-fi lit course I'm taking this year. One especially good story we read involving the tesseract was called A Victim of Higher Space by Algernon Blackwood. My teacher for the class has a model of the 3d representation of a tesseract made out of children's building blocks.

It's nice to see stuff I learn about in school somewhere else... and thsi was something I wasn't sure I was gonna hear about much outside of sci-fi class. I thought it was a cool entry. Hoping to see more like it that I'd be interested in.!

One of my students just did a research presentation arguing for the existence of the 4th dimension, using hypercubes as illustration. My language-oriented brain has a little trouble sliding around this concept, but I suppose that is the way of the 3-dimensional being, eh? This entry is very well written, though. I like the use of Slim and Fred.

Further challenges might be representations of the other regular polytopes in four dimensions ("polytopes" is just a general term for polygons, polyhedra, etc.).

In 3 dimensions there are: the tetrahedron (4 triangles); the cube (6 squares); the octahedron (8 triangles); the dodecahedron (12 pentagons); and the icoshedron (20 triangles).

In 4 dimensions there are: the 5-cell (made of tetrahedra), the tesseract (made of 8 cubes); the 16-cell (made of tetrahedra); the 24-cell (made of octahedra); the 120-cell (made of dodecahedra); and the 600-cell (made of tetrahedra).

In fact for 5 or more dimensions it gets somewhat simpler; there are only three sorts of regular polytope for each dimension.