Nature Cheats to Make Blue

Take a blue jay feather and crush it. The blue does not survive. Grind a cardinal's red feather to dust and the red is still there in the powder. That difference is the whole video. A pigment is a molecule that swallows some wavelengths and hands back the rest, and grinding it up does not change what a molecule absorbs. But a jay feather has no blue pigment in it at all. Nothing down there is blue. What it has is keratin threaded with air pockets, spaced at about the width of a wavelength of light — and at that spacing most of the spectrum cancels itself out and blue reinforces. Destroy the spacing and you have destroyed the colour, without removing anything. Then it turns out nature does this half a dozen different ways. A morpho butterfly makes blue with stacked ridges instead of pockets, which is why its colour flares and dies as it turns while the feather's barely moves. A Nessaea butterfly really does carry a blue pigment. A hydrangea makes the same molecule come out pink or blue depending on how much aluminium it can pull out of the soil. The sky scatters short wavelengths out of sunlight in every direction. The ocean absorbs the long ones with depth until only blue is left to come back up. Six mechanisms with nothing in common, all ending in the same place. Blue is not an ingredient. It is a result — and it does not finish happening until it reaches an eye. 00:00 A feather that loses its colour 00:38 Where is all the blue 01:41 How colour normally works 02:39 Inside the feather 04:19 The morpho, and turning things 05:16 Blue pigment is not impossible 05:47 The sky and the sea 06:43 And then met you Subtitles: English (CC)