Blue light special

By Patchen Barss

Why are blue things blue?

Blue dyes, blue eyes, blue skies and even blueberry pies have one thing in common: they all generate electromagetic radiation with wavelengths between 450 and 495 nanometers – the range commonly known as “blue.”

They don’t all do it the same way, though. Blueberries have a pigment called anthocyanin that can be blue or purple. Indigo dye contains a nitrogen-based substance that must react with oxygen to turn blue. Blue eyes have no pigment at all, but instead get their colour from refracted light. The blue of the sky results from a complex quantum phenomenon known as Rayleigh scattering.

That’s just physics and chemistry. There’s also biology and brain science to consider. Light enters the eye, hits the retina, and stimulates receptors that kick the brain’s visual cortex into action. Neurons fire, and somehow the thought “I see blue!” is generated.

At least, that’s how it works in North America. (If you’re neither colour-blind nor a tetrachromat. And are a human being.)

The Japanese concept of blue, known as “aoi” also includes some shades of green. The Russian language treats light and dark blue as separate colours. Dogs have only two types of colour receptors compared to humans’ three, and thus have much less sophisticated colour differentiation. Butterflies, with eight spectral receptor types make human perception seem paltry.

I can talk about this until I’m blue in the face, but here’s the point: Every child understands colours, but the hues in a Crayola box become vastly more difficult to pin down when you revisit them with a researcher’s sensibility. Not only is blueness more mysterious and changeable than it at first seems, but it is also part of a continuum, a spectrum of electromagnetic radiation that extends far beyond anything any known living creature can perceive.

The mysteries of the electromagnetic spectrum are on my mind for two reasons.

First, I’m thinking about solar power. In particular, Karin Hinzer, a University of Ottawa researcher who is working to improve the efficiency of solar panels by drawing on wavelengths of electromagnetic radiation that the human eye can’t perceive. Her work speaks to fundamental questions about light and colour – why do some wavelengths pass straight through certain materials, but get absorbed and re-emitted by others? What’s actually happening on an atomic or molecular scale? How can we move beyond our perceptual limitations and tap into a bigger picture?

Second, the National Public Radio program Radiolab, has a funny, lyrical, unsettling new episode called “Colors.” Among other things, it creates an eerie feeling that  a world of wonders exists just beyond what we can see, hear and feel. As Hinzer’s research demonstrates, there is indeed such a world, and not only can we access it, but we can make use of what we find there.

If you care to see light in a new light, I recommend the following:

1. Read Karin Hinzer’s profile on this website.

2. Listen to Radiolab’s Colors podcast:

3. Visit Hinzer’s SUNlab site, which contains more detail on how she’s advancing solar power technology by tapping into the invisible.

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