This staircase goes on forever. Or does it?
This so-called "impossible object" takes form when the brain attempts to turn a 2D image into a 3D object. (Stuart Patience/)Glance at the stairs above.Find the base...rather, spot the top. Upon closer examination, you’ll realize that there is no beginning or end. There’s no way that’s feasible, right?These familiar steps, called the Penrose stairs, are a type of “impossible object”—a construction that could not exist in reality even though its individual pieces look totally valid, says Erez Freud, a cognitive neuroscientist at York University in Toronto. The paradoxical item takes form when the brain attempts to turn a 2D image into a 3D object.From years of trusted experience, our noggins assume lines are always straight and corners precisely 90 degrees. But those facts can’t be true and still create this eternal four-way staircase. You can’t walk upstairs forever, especially in a loop. Normally, two regions in the brain’s visual cortex—the...