Tesseract - Wikipedia, the free encyclopedia

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Yes, what about it?

If you're interested in 4D you might enjoy http://www.superliminal.com/cube/cube.htm (requires Java)

No mention of Madeleine L'Engle's "A Wrinkle in Time"?

I also remember a short story about a guy who builds his house using a tesseract as the model. More inside than outside--- until it collapsed! :)