(RED) RED SHIFT 1
The ancients used cinnabar, the red sulphide of mercury, for bright red. Zosimus spoke of it coming from the stars. Vermilion is the re-synthesis of mercury and sulphur into the likeness of the cinnabar from which the mercury was extracted. After vapourising and recondensing into the top of a flask, the flask is broken. It's almost black. As it is ground it becomes red. Cennion reckons that if you ground it every day for twenty years the colour would still become finer and more handsome. The change from black to red isn't a chemical one, but structural. A matter of light response to internal shapes. For this reason, vermillion isn't liked for painting on exposed walls. Modern manufactured vermillion is more prone to this structural change than its mediaeval equivalent.
Plant germination is controlled by phytochrome (a pigment) which changes its structure in response to red and far-red light. Red stimulates germination, far-red inhibits it. The process is reversible, a kind of solar-energy storage. Both red and far-red are present in "white" daylight, but red dominates.
Electron cameras that are unduly sensitive to light of long wavelengths are known as red-conscious. The red shift refers to the same spectral dimensionality. It's the displacement of nebular spectral lines towards the red end of the spectrum. When the red shift is interpreted as a Doppler effect it leads to Hubble's law, where velocity is proportional to distance and velocities of up to 80% the speed of light have been measured.