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  • From ancient Egyptian sarcophagi bathed in lapis lazuli to a synthetic pigment accidentally

  • created in a lab that’s already being patented and marketed asthe bluest blue ever,’

  • blue is the rarestand perhaps the most celebratedcolor on earth.

  • But why is it so hard to make and why are we are so enamored with it?

  • The science of blue pigment is what makes it minerally and biologically rare in nature

  • and incredibly difficult to recreate synthetically.

  • And its rarity, it’s special-ness, is what makes it so culturally significant throughout

  • all of human history.

  • Since about 6700 BCE, the first known usage of blue pigment by humans, blue was difficult

  • to get your hands on, and then hard to process for use as a paint or a dye.

  • This meant blue pigment was very expensive and valuable, only to be used for special

  • occasions and high art, making it the hallmark color of the wealthy, the royal, and the holy

  • from the very beginning of culture.

  • Despite its eventual role as a treasured part of our visual world, some linguists and historians

  • actually have a theory that maybe humans couldn’t see blue until relatively recently in our

  • history because a word for blue doesn’t occur in almost any ancient language. The

  • very first recorded society to have written down a word for blue were the ancient Egyptians

  • also coincidentally the first culture to produce a blue dye.

  • So it could be that the main blue things in our worldlike the sky and the oceanare so

  • huge, so all-encompassing, so ever-present, that it didn’t occur to us to describe their

  • color.

  • They are simply the sky and the sea, the origins of our world, stretching as far as we can

  • see.

  • And perhaps blue occurred so infrequently in the rest of the natural world, it just

  • never necessitated a word of its own.

  • But if its cultural significance is due to its scarcity, why is it so rare?

  • It all comes back down to the science.

  • First of all, almost everything in nature that looks blue is a lie.

  • The vast majority of living things actually can’t produce blue pigment.

  • The other bright colors we see in the wild, like the reds and oranges and yellows, are

  • colors an animal can become because of what they eattheyre ingesting that pigment

  • and processing and recycling it to give them their color.

  • But most animals that seem blue to uslike this butterfly or this birdactually aren’t.

  • And for the most part, with this notable exception, it’s not because of what theyre eating.

  • Many blue animals actually have color built into their architecture insteadthe blue

  • that we see here is actually due to microstructures in the feathers or scales of these creatures,

  • which structurally filter out all wavelengths but blue, almost like a tiny prism tricking

  • you into seeing a color that isn’t caused by pigment.

  • That’s even the case for our blue irisesit's microstructure, not pigment!

  • And it’s not just the animal kingdom that has workarounds—’trueblue is equally

  • rare in plants.

  • Some plants do produce pigments called anthocyanins, but none of these are actually blue.

  • Instead, plants can tweak the pH and arrangement of the molecules of a red anthocyanin pigment

  • to reflect different wavelengths of light to produce blue-tinged flowers. But this

  • is pretty rare.

  • Many of our common decorative flowers, like roses and tulips and carnations, just don’t

  • make blue.

  • We can put them in artificially dyed water to get an unnatural-looking glow, but scientists

  • are also trying to modify these flowers to get them to produce blue naturally.

  • One team was successful at making blue chrysanthemums, but whoa was it hard, and involved

  • extremely detailed and finicky metabolic engineering.

  • But why?

  • What about blue makes it so tricky and special?

  • There’s no one straight answer, but the key probably lies inside the physics of pigments.

  • To make a true color with no shortcuts, an organism has to produce a pigment, which, if

  • were gonna define it technically, is a compound that absorbs some wavelengths of

  • visible light and reflects the one were seeing.

  • Now, as we know, light is a kind of energy.

  • A pigment that absorbs a certain wavelength of light has to absorb that light energy and

  • then has to do something with it, has to put it somewhere.

  • That usually means that electrons in that pigment get bumped up to a higher energy level,

  • called an orbital.

  • So if we picture the pigment as including a cloud of electrons on different rungs, a

  • photon of light can bump an electron up another orbital, but the amount of energy coming in

  • from that light has to match the distance between orbitals.

  • This is actually the fundamental reason that different pigments look differently colored:

  • each different pigment compound has a differently sized energy gap between orbitals, and can

  • only absorb specific wavelengths of light that will excite an electron enough to jump

  • over that gap.

  • The pigment needs to have the right atomic structure and electron arrangement to absorb

  • certain wavelengths, leaving the other wavelength to bounce off the pigment and hit us in the

  • eyeball.

  • I know, I’m right there with you—I was very surprised, but delighted, to learn that

  • color has this much physics involved.

  • So, where does all this subatomic dancing leave us when it comes to blue?

  • Well, to look blue to the observer, remember that a pigment has to absorb wavelengths that

  • aren’t blue.

  • Which means that, among other wavelengths, that pigment needs to absorb red light.

  • Red is the lowest energy level wavelength on the spectrum of visible light.

  • And that means that the orbitals need to be uncomfortably close together for red light

  • to push an electron from one orbital to the next because red, well, doesn’t have a

  • lot of energy.

  • And this kind of molecule with close-together scrunched up orbitals is apparently very difficult

  • to make.

  • Blue’s rarity is due to its science. Its rarity is its allure.

  • And aside all from the psychological theories about our attraction to blue being because

  • it makes us feel calm, pigment science may have surprisingly important applications outside

  • of art, design, and flower arrangements.

  • Pigments like anthocyanins are antioxidants and are antimicrobial, and some scientists

  • are researching how they could be incorporated into health-boosting foods.

  • Structural pigments like the ones in butterfly wings could lead to the development of colors

  • that we could grow, kinda like how you grow sugar crystals, with applications from industrial

  • paintsto cosmetics that don’t require animal testing.

  • So blue is much more than just pretty, but it plays pretty hard to get.

  • And I have a feeling well probably keep chasing it down for quite a long time.

  • What do you think?

  • Why is blue so fascinating and precious to us?

  • Let us know down in the comments below, and make sure you subscribe to Seeker to tag along

  • as we explore the world around us.

  • Thanks for watching.

From ancient Egyptian sarcophagi bathed in lapis lazuli to a synthetic pigment accidentally

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