What fresh hell is this? A mathematician has created a spinning wheel that’ll probably make your mind explode if you try to understand it.
The illusion was posted in a short video on Instagram by the page @physicsfun. It was created by mathematician Kokichi Sugihara from Meiji University in Japan, who’s known for messing with our minds like this.
“Spin this arrow 180 degrees and it still points to the right,” the description reads. “[O]nly in a mirror will it point left (and only to the left).”
The obvious answer for how this works is magic. Sugihara is some sort of wizard, and we’re all being subjected to his heretical ways. God help us all.
The other possibility is that it is science. If you watch the video, the arrow is tilted up to reveal its true shape, sort of an oblong object with two pointy bits.
If you then place a mirror behind the arrow, it appears to point in the opposite direction continuously. A clue!
Thankfully, there is a scientific answer, and we don’t need to burn Sugihara at the stake just yet. How does it work exactly? Well, we’ll let Gizmodo explain:
“Sugihara uses his skills as a mathematician to design uniquely-shaped 3D objects that can change their appearance based on the angle you look at them,” they write. "When viewed from above, this ‘arrow’ is a perfectly symmetrical, but ambiguous shape. From a different perspective, however, the undulations on top of it make one side appear to have more of a point than the other, and when your brain tries to match what it’s seeing to something it’s seen before, a pointing arrow is the obvious choice.”
This is a trick that Sugihara has actually shown us before. His famous “Ambiguous Cylinder Illusion” employed a mirror to turn square blocks into cylinders in a mirror. You can check that one out in the video below.
If you want to amaze your friends with the pointing arrow illusion, then you can create your own origami arrow. Note, I had a go at doing this, and it is exceedingly difficult. Maybe I'm just not a very good wizard.
(H/T: Gizmodo)
