Scientific St. Albert
The Gazette is using science to answer questions from students of all ages about the world around them. Send in your questions to [email protected].
I have to repaint my walls this summer. Should I stick with brown, or be adventurous and make it gamma-ray coloured? Or radio waves? Or smurple?
Four Winds Public student Ethan Keller (who submitted an astounding 26 questions to Scientific St. Albert) has also wondered about these other colours of the spectrum, asking, “What if we could see ultraviolet light, X-rays, radio waves, gamma rays, infrared, etc.?”
Science suggests that Earth would be a much brighter and colourful place if we could see the entire electromagnetic spectrum. We’d also never see “black” again.
Way beyond RGB
Light is made up of all sorts of wavelengths going from essentially zero to as long as you want, explained Sharon Morsink, a physics professor at the University of Alberta. Humans can perceive light that’s 400 to 700 nanometres long (bubble-membrane-thick, says NASA), which we call visible light. We don’t see longer waves such as infrared (hair-sized), microwaves (baseball), and radio waves (office tower+), and we miss out on shorter ones such as ultraviolet (rhinovirus), X-rays (atom), and gamma rays (atomic nucleus).
Let’s work our way down the spectrum.
Since radio waves can be infinitely long, it would be pretty tough for humans to see them without eyes the size of satellite dishes, Morsink said. We’d likely perceive radio towers as glowing different colours depending on what they were transmitting.
“Every radio station would have its own radio colour,” she noted.
Radio towers would likely have a steady glow to them as radio waves get transmitted millions of times a second, said Christopher Mann, exoplanet scientist at the University of Montreal. You might see them flash with slower transmissions, such as Morse code. Because radio waves bounce off Earth’s ionosphere (which lets us send straight-line radio waves around our sphere-shaped globe), the sky would likely have a radio-coloured tinge to it at all times.
Mann said microwaves tend not to show up much on Earth, but they’re everywhere in space. Indeed, you can’t get away from them — no matter where you look, you can see the cosmic microwave background radiation left over from the Big Bang. If we could see microwaves, space itself would have a colour.
Most Earth creatures don’t see infrared, because if they could, the heat would cook their infrared receptors, said Peter Heule, live animals supervisor at the Royal Alberta Museum. Instead, most creatures use other senses such as touch to perceive heat.
Infrared vision would make anything with heat in it glow, with hotter objects glowing brighter, Mann said.
“You would never again touch a hot frying pan,” he noted, as you could tell its temperature at a glance.
Infrared vision would make it impossible for us to see total darkness (or “black”) ever again, Mann said — everything in the universe has heat in it, so everything would glow. Not even closing your eyes would help, as your eyelids produce heat. You’d have to step into a room chilled to absolute zero to see true darkness with your infrared vision, and that won’t happen, since nothing in the universe can get that cold.
Ultraviolet vision would let us spot the UV-reflective patches flowers use to direct pollinators toward pollen, Heule said.
“It’s almost like a little landing strip.”
We’d also be able to spot goldenrod crab spiders waiting to ambush us. Normally, these tiny spiders turn yellow or white while reflecting ultraviolet, making them camouflaged in visible light while looking like big, bright flowers in UV.
Earth’s atmosphere blocks most X-rays and gamma rays, so we wouldn’t see many of them outside of dentist offices and particle accelerators, Morsink said.
You would see these dangerously high-energy rays if you were looking at a chunk of uranium, Mann said.
“It would be a strange and unusual colour,” he said, one we would likely perceive as dangerous due to its rarity.
Describing them
It’s tough to say what it would be like to actually see all these new colours in the spectrum, Mann said — it would be like describing “red” to someone who had never seen it.
“I don’t think our language or even our brains are really equipped to handle that.”
We could ask the peacock mantis shrimp. Heule said these rainbow-hued crustaceans have 16 colour receptors in their eyes compared to a human’s three, and can see both UV and near-infrared light.
“They just have a broader rainbow they can see.”
Astronomers use different parts of the spectrum to spot rare and distant objects, Mann said. Galactic dust often blocks visible light, but we can see through them with longer infrared and radio wavelengths. Radio waves can point out pulsars, while X-rays suggest black holes and neutron stars.
Heule said being able to see X-rays, radio waves, and such might be a bit overwhelming, but it could also be pretty amazing.
“You think a sunset looks good now? Imagine if we could see all those things!”
