The Blackest Black
The center square appears much blacker than the other squares. Why?
It is an opening that leads into a black box designed to trap light. Light that goes in bounces again and again off the dark walls inside, and some of it is absorbed at every bounce. Almost none finds its way back out to your eyes, so the opening looks much blacker than ordinary black ink or paint.
Compare the black box with marker black and printer black. How different can “black” be? Which one is the blackest black?
Where does the missing light go? Do you think the box gets warmer than the surroundings? Come and find out.
Additional Information
Black is what we perceive when little or no visible light reaches our eyes.
That is also why most of space looks black: between stars and galaxies, very little visible light is arriving from those directions.
Some engineered materials can be quite black too. Vantablack, made from forests of tiny carbon nanotubes, absorbs more than 99.9% of visible light, making coated objects look strangely flat because their shapes and shadows almost disappear.