[Miss Jordan]

Some Ambiguous Objects

Here are some ambiguous objects:











1. The Schroeder staircase: Is this staircase rightside up or upside down (which is the wall closest to us)? You should be able to see the ambiguity without viewing this upside down.








2. The Necker cube: Which face is in front?









2a. The Necker cube, part 2: One corner is convex towards you, one is concave. Which is which? This is one of my favorites, as I can't get one of them to stay convex or concave; it changes over and over.








2b. The Necker cube, part 3: Is this a small cube in a corner, or a cubic bite out of a larger cube?3. Slice of pie or missing slice of pie: Is this the last remaining slice of pie (seen upside down) or is it a whole pie with one slice missing?

Some Impossible Objects

Here are some "impossible" objects:













1. The Freemish crate: See the next one.













1a. Asymmetric Freemish crate: I don't know which is the original. This is drawn about as often as the one above.









2. The Penrose staircase: Often drawn by M. C. Escher. Clockwise is downstairs forever.






3. The tribar: Another impossible object by R. Penrose. It's hard to know how to color it, as the interior becomes the exterior.





4. The tribox: This is just the left end of the tribar, twice.









5. The Penrose triangle: Another famous impossible object by R. Penrose. This is sometimes called a tribar (see #3, above).









6. The ambihelical hexnut: That is what one site on the WWW calls this impossible object. I don't know who invented it.7. An ambiguous ring: I don't know who invented this. By the way, this is not a Mobius (Möbius) strip.