Through The Looking Glass

Understanding how light travels is the key.

Look through the glass above, you'll find the black and white bars bizarrely switch direction. The explanation is actually not complicated. First, water is denser than air. When light hits the surface of the water, it causes a redirection of the light wave, ora  phenomenon called refraction. But refraction alone couldn't solve the puzzle. The complete reversal of the bar's direction comes from the converging effect of the curved glass. As light converges at a certain point between our eye and the glass, it continues to travel towards your eye, but it has crossed and the image has reversed.  Read the more in depth explanation here.