My dad used to own a company that made wheel balancers, they work by spinning a wheel really fast, then flashing a light with a known refresh rate, and seeing how the wheel behaves (if the wheel looks like it is standing still, then it is perfectly balanced, otherwise it is unbalanced, and it is speeding up and slowing down because of gravity).
Although the refresh rate of artificial light could be manipulated to create very interesting effects, even in natural light you can see wheels rotating backwards, or standing still, or forwards in slow motion, because of the exact thing mentioned in the article.
I was a kid when my dad worked with that, and I was always fascinated, I could keep staring at the spinning wheels during testing of our product for hours.
Although the refresh rate of artificial light could be manipulated to create very interesting effects, even in natural light you can see wheels rotating backwards, or standing still, or forwards in slow motion, because of the exact thing mentioned in the article.
I was a kid when my dad worked with that, and I was always fascinated, I could keep staring at the spinning wheels during testing of our product for hours.