How Butterfly Wings Display Brilliant Colors
Ever wonder how butterflies flash brilliant colors from their wings? It's not done with pigment. Instead, butterflies use a trick of light that sounds like something out of Star Trek: "photonic crystals."
Photonic crystals are precise arrangements of geometrical patterns at microscopic scales.
On butterfly wings, these patterns might be bumps, holes, ridges, hexagonal arrays or other shapes, often in 3-D arrangements. The shapes are spaced very close to the wavelengths of light in ways that intensify the reflected light of certain colors and absorb others. You've seen this effect in the colors in oil on water -- depending on the angle, some colors become vivid -- except in the case of butterflies, the effect is controlled by the genetic code for purposes such as species recognition, mating display, warnings to predators, and camouflage. The control is so effective that the colors can be seen from a wide range of angles, even when the butterfly is flapping its wings in flight. The iridescent blue of the Morpho butterfly (seen on the cover of the Metamorphosis DVD) uses this technique, while and the oranges and yellows of the Monarch are produced by pigments.
Many butterflies use a combination of pigment color and structural color. Some birds, such as hummingbirds and the Bird of Paradise, employ similar combinations of photonic crystals and pigments in their wing feathers. That such unrelated animals would use the same technique presents a problem for evolutionists. They can only offer a hand-waving argument called "convergent evolution" to try to explain the similarity.
Within the last decade, scientists and engineers have taken a keen interest in natural photonic crystals with the hope of imitating them. It has been difficult for engineers to imprint precise patterns on artificial materials the way butterflies do so easily, patterns that are less than a millionth of a meter in spacing. Scientists at Penn State tried a more direct method by making a mold directly from a butterfly wing.
With increasing success we can hope for exciting butterfly-inspired applications: brighter clothing, wall coverings and paper; safety helmets and vests that are easier to see at night; sensors that change color with shape; money with superior counterfeit protection; perhaps even whiter teeth. All of these benefits can be produced without the need for pigments or power sources.
As with so many cases of human ingenuity, we find that nature had it first. The next time you see the brilliant colors on a butterfly, think about the remarkable geometry that makes it possible. Surely the butterfly did not invent this marvel by itself. It is an ability that seems over-designed for mere survival. As Paul Nelson said in Metamorphosis, "You need a cause with an artist's eye for color and pattern and shape, a sense of beauty and aesthetics that extends way beyond utilitarian purposes like camouflage or species recognition. There may well be in butterflies aspects of beauty that are there not for the sake of reproduction or survival, but for us to appreciate."
To learn more about butterflies and the evidence they reveal for intelligent design, visit Metamorphosisthefilm.com.