In both ( 1 ) and ( 2 ) cases the distance and speed of a short while back are used due to the speed of light delay combined with a nonzero distance between A and B . This " appearing heavier " effect would then be notable in the spectral profile of the observed color.
12.
Gauguin said, " Art is an abstraction; draw it out from nature while dreaming in front of it, " and that explains how we can see, for instance, van Gogh's portrait of him, a strange, spectral profile in shadow, more as an apparition than as a likeness.
13.
The heat emitted by isinglass, for example, is different from that emitted by lampblack, and the heat emitted by cloth, or paper, differs from both . " Looking at an electrically-heated platinum wire, it is obvious to the human eye that the heat's spectral profile depends on whether the wire is heated to dull red, bright orange, or white hot.
