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Physics That Makes Blue Jays Blue When They Really Aren't

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    This never occurred to me before. I, like most people take for granted things I see everyday such as birds. Blue jays and cardinals are the most memorable in my day-to-day. I can even remember the last time I saw a blue jay. Both birds just stand out, obviously. Blue jays for instance aren't actually blue.

    Most colors in nature come from pigments that absorb the majority of light wavelengths except for those that are reflected to give off color that the naked eye can see. Apparently, blue pigment is very rare in nature. So when it comes to bluebirds such as the jay, the blue actually comes from tiny air pockets that are inside of the feathers. These air pockets scatter light to create the blue color that we see.

    Vinothan Manoharan at Harvard University and his colleagues wondered if red colours were impossible to achieve without pigment. “We thought, maybe the birds know something we don’t,” he says. The team studied nanometre-scale plastic beads – inverse versions of the air pockets of blue feathers. Changing the size of beads alters how light scattered from nearby ones interferes, enhancing particular shades. Manoharan’s team used large beads to try to enhance red light, but purple appeared instead. The unexpected blue component appears for the same reason the sky is blue, Manoharan says: individual particles preferentially scatter blue light.

    For now, it's agreed that redbirds such as cardinals get their color from pigment alone. Although there's a slight possibility that you can get red coloring in feathers from light scattering about. A professor at Yale explained why it's unlikely for birds birds to use holes in their feathers to make red. Which it makes sense when you think about it. The theory is, if you try to create red by scattering light in such a way, light scatters multiple times within a feather. This enhances other colors that wash out the color red.

    Pretty cool huh? I had no clue about this. I'm sure someone already knew this, but you learn something everyday I guess. What other examples can we come up with that show how the physics of light can trick our brain into seeing something else entirely?

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    That's really cool. This post inspired me to look around on YouTube to see more visually how this works, and I came across this video, which I highly recommend. Explains this very well. And they talk about Bluejays too, around the 4 minute mark.

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    Very interesting, and thanks for the vid. It put it way better than I could of. I'd be surprised if this hasn't already been featured on Bill Nye of something. I hear that some scientists are looking to replicate and use this for making colored screens for devices such as the Kindle.