Here's a neat little science experiment: put three drops of dye into a cylinder of liquid, mix up the colours by turning the handle, and then reverse the process:
Pretty mind-boggling, eh? Now, I'm sure this isn't a trick in the sense that there's no duplicity here, but I think it *is* an illusion in that the three colours of dye never actually mix because they're inserted at different depths (from the wall) in the cylinder. I'm guessing that the dyes are smeared out in the laminar flow of concentric cylinders of liquid, but the camera is looking through three "smears" of dye that don't aren't actually mixed. If the dyes *do* mix, I can only assume someone repealed the second law of thermodynamics without telling me. But then again, fluid dynamics was never my strong suit: to this day I still believe that the Bernoulli effect is what lets airplanes fly. Any experts out there care to explain what's going on?