Allow Us to Explain How This Straight Pole Fits Through a Curved Hole

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A curved hole versus a straight pole. Photo: Cults3D/Reddit

It has been a particularly long week here on the World Wide Web, so here’s a nice optical illusion to stare at until your brain turns to mush. Today’s mind-bender, which comes courtesy of Reddit, features a rotating pole that somehow — hence “illusion” — appears to fit through a curved hole.

Photo: Cults3D/Reddit

In a YouTube video, the creator of the illusion, a channel called Make Anything, which is devoted to all things 3-D-printed, breaks down what is happening/giving you a headache. The video breaks down the rotating device into three pieces: the curved-hole piece, the rotating straight pole, and the rotating base the pole sits on and that turns. The first thing to note is that the pole is not attached perpendicularly to the base; it’s at an angle. Because the straight pole is at an angle, the base of the pole passes through the hole first. Then, each section of the rest of the pole slowly passes through, working upward until the whole thing fits.

“Essentially, this hole doesn’t have to match the shape of the pole,” the video explains. “Instead it matches a cross-section of the shape that is created when you spin this pole around a circular axis.”

A look at the cross-section. Photo: Make Anything

[Insert Confused Math Lady meme here.]

Here’s How This Straight Pole Fits Through a Curved Hole