Black Body Radiation

Black body radiation and black hole
A piece of black paper or fabric (cloth) with a variety of surface structures—smooth, velvety, glossy, matte, etc. is needed. Make a coin-sized hole in the center. Next, take a cup with an entirely white interior. When you cover the white cup's opening, try to guess what will be visible through the cut hole.
Regardless of how much black cover you apply, there will always be more black in the hole that covers the cavity. Specifically, all light is absorbed by the hole and not a single visible wavelength is reflected. White represents the presence of all colors, while black does not appear to be a color; black represents the absence of any color.