The striking metallic colors on the wings of some butterflies change depending on the angle from which they are viewed. The wing color of one species is so pure and intense that it can be seen from a half mile(805 m) away. What makes it remarkable?
Consider: Rows of tiny concave surfaces on the wings of a green swallowtail butterfly reflect light in various ways. The center of each concavity reflects yellow-green light, while the edges reflect blue light. Also, light at the center of a concave surface is reflected directly, but the light striking sides first bounces through a surface of multiple layers, which amplifies and partially polarizes, or rotates, the light waves. The final mix is called structural color because of the complex way in which it is produced. It took ten years for researchers to produce a simplified replica of the butterfly's sing surface. Such technology, they hope, will lead to bank notes and credit cards that are harder to forge and solar cells that are more efficient at collecting energy from the sun. However, duplicating the surface of a butterfly's wing is challenging. "Despite the detailed scientific understanding of optics," writes Professor Ullrich Steiner of Cambridge University's Nanoscience Centre, "the astonishingly varied colour palette found in nature often surpasses the optical effects that can be generated by technological means."
"Is this all come out by chances? Or was it designed?"
