Maurits Cornelis Escher, aka M.C. Escher (1898 – 1972), was a Dutch graphic artist known for his often mathematically inspired woodcuts, lithographs, and mezzotints. These feature impossible constructions, explorations of infinity, architecture, and tessellations. If you do a search on Escher's waterfall, you will find a lot of information that explains how his methods tricked the human brain to perceive something that is not what it appears to be. There are videos, physical models, computer models, paintings, drawings, and written theses. Even knowing that the image does not comport with real-life experience, figuring out exactly how the spoof is executed can be difficult - if not impossible (to some). In this video, a resourceful young man uses a physical model with a carefully placed camera to pull off the illusion using tinted water that appears to actually flow through the contraption. Lots of people responded to his video with ideas, but I'm not sure whether anyone actually got it right. Can you figure out how he did it?
Escher's Original Lithography
Escher's Waterfall in LEGO Blocks by Andrew Libson