In color, the absence of all (or nearly all) reflected light from a surface, as in the printing of an ink with no perceptible hue. Technically, however, there is no such thing as a "perfect black"; even the darkest materials that have been found to exist (such as lampblack, soot, pitch, or black velvet) reflect as much as 3% of the light striking it. Totally non-reflective blacks have been conceptualized, most notably the theoretical blackbody of physics and the perhaps as equally theoretical "black hole" of astronomy, the latter of which is only totally black because its intense gravitation prevents any light from escaping. (This would not make a good basis for printing inks, however.) Both those "black" objects—so far as we know—do not really exist.