Hello there, skeptical friends, and skeptical foes,
I got my Scientific American today, Which is very surprising, because I thought it took about 2 weeks to send post from America to Australia, but there you go. I always thoroughly enjoy getting my Scientific American each month, and I always find half a dozen articles which I consider blogging for. I found an article today which was about some of the clever light tricks which animals play on us, but not about the colour changing squids which go black and then white and then black and then white when a pretty lady comes past or when a compeditor squid comes along. This article was about the microscopic patterns on bird feathers, butterfly wings and worms, which make colours which don’t look like what they really are. I will be blogging about a few of the tricky light patterns mentioned in this article in future posts, but today’s article is about A strange pattern found on Butterflies.
The emerald swallowtail butterfly lives in South-East Asia, and has a wing-span of about 8 – 10 cm, and is one of the most prominent butterflies in this area. They have a distinctive green and black pattern on their wings, and it has been discovered that the colour of the wing is not actually green, but it is a combination of blue and yellow colours.
The green parts of the wing are covered in tiny, bowl shaped dimples just a few microns across. The dimples are lined in layers of chitin which act as mirrors, which only reflect light of certain wavelengths. In the bottom of the bowls are chitin which reflect only yellow light, while around the top of the bowls are chitin which only reflect blue light.
Researchers at Georgia Institute of Technology tried to replicate this effect, with success. They created this pattern by first making a polymer, and vaporizing water, letting it condense onto the polymer, and letting the water droplets sink into the polymer, creating even, uniform, aligned bowls. They then microscopically dusted the polymer with layers of titanium oxide and aluminium oxide, and the result they turned out with was comparable to what was found on the butterfly. The researchers also found that under a polarizing filters, the yellow light from the wing and polymer pattern did not show, leaving only the blue light.
This polymer pattern could provide an extra layer of protection to credit cards and bank notes. A small half-inch square on every bank note and credit card, similar to the watermarks on bank notes in Australia , would add an extra layer of protection to the notes. All that would need to be done is put the bank note under a polarizing filter, and you would have an easy authentication check, adding to the layers of defense already present in notes and credit cards.
as can bee seen, nature has found simple ways of producing amazing colours and patterns, and as has been shown on so many scientific disciplines, physics, engineering, chemistry, technology, the best solutions to some problems were solved thousands of years ago, by a small bug that eats wood, or something of the like, and we just have to find out how to replicate them. That’s all I have to say. I will leave you with a quote from Carl Sagan, “Extraordinary claims require extraordinary evidence.”