The published photos can be said that everything posted on Instagram is a distortion of reality (especially if you are a celebrity), but a video shared by science account Physicsfun this week did test the laws of optics.

The video shows a simple plastic toy in the shape of an arrow pointing to the right. When one hand rotates the arrow by 180 degrees so that the tip of the arrow points to the left, something strange happens: the arrow still seems to point to the right. In fact, no matter how many times the arrow rotates, it always points in the right direction. What's going on here? "

There is no magic and post-production skills in the game; This evil little arrow is actually a cunning optical illusion, designed by mathematician and professional brain-dead Kochi Sugihara.

Sugihara is a professor at Meiji University in Tokyo and an award-winning illusion artist. He has participated in the annual best illusion competition of the Neurology Association for four times and won two awards, usually because of his geometrically complex 3D printed illusion objects, such as the arrow in the above picture.

Sugihara first released this maddening arrow in a paper published in Symmetry magazine in 20 16. Sugihara put forward a new optical illusion in his paper, which is called "abnormal mirror symmetry" and is essentially an object. Pointing in one direction in reality and pointing in the opposite direction in reflection seems to break the typical mirror symmetry rule.

"When we see an object and its mirror image ..." What we perceive does not necessarily follow this physical law (mirror image symmetry), because what we perceive is the result of brain image processing, "Sugihara wrote in the paper, which led to optical illusion.

Mathematicians provide some complicated equations in his paper to explain how this illusion is possible, but what you really need to know is that you always use the forced perspective of the right arrow to use your brain to find the hobby of right angles where there are no right angles.

Pause the Instagram video at the mark of 16 seconds, and you will find that the arrow is not a real arrow at all, but in the middle, covered with almost invisible internal curves. When observed at a certain angle and under certain lighting conditions, these curves will induce your brain to interpret the curves as angles-even if the object rotates 180 degrees.

This arrow, which is always to the right, is an example of Sugihara's so-called "ambiguous cylinder illusion", which will make your brain's thirst for order go against itself. Because ambiguous cylinders are neither perfect circles nor perfect angles, your brain can actually see them at the same time, as shown in the video of Sugihara below.

It looks amazing, but it's just that your brain is too efficient to find chaotic order. Stranger still, you can sit down, relax and watch a whole color disappear before your eyes.

Originally published in the journal Life Science.