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Paper Dragon

Tonight when I finished work, Anthony and Piper were sitting with Elizabeth looking at dragon pictures on her laptop. After Elizabeth left for the evening, Anthony asked, "can we look at more dragons?"

So we played some pretend-animal games and discovered on Tolweb.org that dragons haven't, in fact, ever been cataloged by scientists (and that hippopatamuses are in fact real). But then in hunting for "dragon videos" we stumbled on this cool clip about a Dragon optical illusion.

Look at the pictures carefully. Why does the dragon turn towards you when Anthony turns the base of the model away from you?

The great thing about this impossible object is that you can actually make it yourself by printing out a paper cutout. Grand Illusions has the PDF file posted here, with permission of Binary Arts.

The illusion dragon is labeled as an object for "Gathering for Gardner 3, 1998". Martin Gardner, if you're not familiar, is the recreational mathematician and writer of Scientific American fame; he is probably the greatest popularizer of math and puzzles ever. He was largely responsible for the Conway's Game of Life craze and also sparked my interest in Penrose tiles and other cool topics. Gardner was a big fan of optical illusions and Things you Can Make Yourself, so this sort of object was right up his alley.

I was too young to enjoy most of Gardner's original Scientific American columns, but I read them all later in his books (now you can get them the whole compilation on CD-ROM). And you can read more about Gathering for Gardner here. Seems the events are still being held - by invitation only!

Anyway, the dragon illusion was well worth it, simple to make, and popular with the kids. A tip: after you cut and tape yours together, try viewing it with one eye closed. The illusion will jump straight out at you!

Update 9/4: after playing with the dragon we dusted off Gardner's books and played with other mathematical amusements. Read about Piper's elusive nine-faced hexaflexagons here, and my fun playing with the puzzle variant of Latin squares, building a Sudoku generator.

Posted by David at August 16, 2006 09:33 PM