You’ve heard of infra-red vision, right? You pop on a pair of funny-looking goggles that look like the ones the Doc wears in Back to the Future and then suddenly you have magic eyes — access to a whole chunk of the spectrum previously invisible to your mammalian peepers! No more is your perception limited to the lamentably narrow range of the visible, for the mysteries and wonders of the infra-red are an open book!
Put those goggles on. When you peer now at a live body, you don’t see the hideous mustard yellow of their grandma’s knitted sweater, but mottled gradated patterns that shift and change as their hearts pump warm blood through their veins. When you gaze upon a mural that’s been heated by the sun, you can see the microscopic cracks in its coating from the places where the heat’s leaked in, raising the temperature minutely above their surroundings. Everything is different when you shift your vision to infra-red, and it’s extensively employed for navigation and surveillance, medical imaging and infrastructure.
What if we could see other frequencies, other spectrums?
What if we looked at grandma’s nasty sweater with x-ray vision or radio eyes? I would love to see UV in a neglected greenhouse at high noon and watch the vibrant beams shine through shattered panes. The checkered overlapping rays would dapple the ground and I would fancy that I could say which plants would thrive and which would feel the sunburn sting, in a week or two, when they flowered. Scan a pipe with gamma vision and see where radioactive slop spurts out through hair-thin breaks and fractures. Hug you close with the Doc’s own specs and giggle as the heat rushes, blushing, to your face.
But there’s a problem with my dreaming. When I open up my altervision and see a different spectrum, I lose what I’ve left behind. No eye we know of can see in two vast swathes at once — when I don those IR goggles, I lose both your sweater’s nasty yellow as well as your apple’s lovely red. Everything has a price, and the trade-off here is clear. We can’t just smear our vision out and see everything like the blue-skinned Doctor Manhattan, because our brains are not equipped to process so many signals in any meaningful fashion. The dictates of evolution have gifted us with the eyes we have, and since our sun emits light mostly between four and seven hundred nanometers, that narrow band is what we perceive. The colors in that band are only a shared figment of our imaginations.
We talk about light being more “red” or “blue” than other light, depending on if its wavelength is longer or shorter. Yet I can’t help but think of a funny little alien who grows up near Proxima Centauri (the closest star to our Sun) on a tiny planet not much bigger than the Earth — and a heck of a lot closer, because Proxima’s a red dwarf with far less than half the boiling fusion kick our Sun has. Our alien friend — and let’s call her Yibbly — is part of a species that has evolved in the dim red aura of Proxima, and therefore possess eyes, whether two or three or a hundred, which are suited to this spectrum. Since Proxima emits a measly fraction too small to mention of the Sun’s wavelengths but over 85% of its power as infra-red, it’s highly likely that little Yibbly’s eyes will be attuned to the IR spectrum in all its hotshot glory. What would colors be like for Yibbly? This is a question that is simultaneously impossible to answer and very interesting, because we don’t understand human vision centers particularly well. One thing is for certain — young Yibbly’s crayon box is more likely to contain shades of florg and bunflop than it is burnt sepia.
Yibbly’s world is incomprehensible to us, not only because it’s unlikely to exist according to telescope observations made by cynical, killjoy astronomers*, but because our means of perception are incompatible. What she sees, we can’t see; what we go in for a closer look at, she might not even know is there. A cold, dead rock is invisible to her just as a rising thermal in the air slips by us unnoticed. How then can we reconcile our two worlds in the event that we meet? One solution might be to jump into the world of altervision by slipping on our IR goggles and taking the ol’ rocket out for a visit to our nearest neighbor. But even then we would probably not see the world the same as Yibbly, because our brains can’t tell a tree that’s florg from a ratchetberry bush. Our brain is not designed to handle IR vision — the result must be a bit like the fuzzy picture obtained when trying to tune your TV into the frequencies between stations.
I don’t know what the solution is, especially when we’re not sure whether the color blue we see is the same as others or if we’re missing out on some really spectacular shade that everybody but us is in on. It’s a bit of a cosmic joke or quandary that there’s this wide-as-you-like spectrum of beautiful electromagnetic radiation stretching from here unto the furthest edge of the universe, and the best we can do is render it using visible’s drab palette. It’s about as much as anyone can do — Yibbly’s astronomers face the same problem — but I can’t help but wonder what other colors we’d see if we possessed an altervision in another plane of existence.
*Note: all the astronomers I know are actually quite nice people. Just don’t let them suck you into a conversation about black holes — you’ll be stuck for an eternity, and you won’t even leave with more information than you came in with.