Hypnotic illusion gifs show the beauty of math

The white circles in this gif travel in a straight line across the diameter of the black circle. In the process, they accelerate toward the center and decelerate away with the velocity of a swinging pendulum.

Here's another colorful illusion with the same pendulum movement of the circles:

Warning: staring at the gifs too long may cause flashbacks to playing Tempest:

(via r/illusionporn)