[math-fun] Puzzle: Skew planes in 4-space?

Fred's query reminds me of the time in 1994 that I gave a lecture -- about 4-dimensional space -- to the Hampshire College summer math program for mathematically talented high school students. Some brilliant youngster asked me whether there could be skew (2D) planes in 4-space. (Skew meaning neither parallel nor intersecting.) I thought about it for a few seconds . . . and then a few more seconds . . . and had to admit I didn't know. But I went home and soon figured it out. Can you? --Dan ________________________________________________________________________________________ "Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read." --Groucho Marx