Museletter the Seventy-fourth

To celebrate these many holidays of lights at the darkest time of the year, this is my second newsletter — sorry, museletter — dedicated to the topic of light: what it is, how we experience it, and (of course) some lesser-known and fascinating factoids about it.?

Enjoy!

Tuning In

Imagine an old-time radio, with a knob that you can turn to "dial in" a station playing music. What you're doing is focusing the receiver on a specific vibration of energy that is pulsing in the space around us. We call that energy "radio waves," but when you turn it up — literally adding more energy to the waves — we call it infrared light. Add more energy and something amazing happens: we can see it! That's because the receptor cells in our eyes are "dialed in" to very specific stations: red, green, and blue.

That's right: the energy that the eyes can see is exactly the same thing as the energy that powers radio, WiFi, Bluetooth, microwave ovens, and more. It's just that we don't have a knob, like a radio, so our eyes are fixed at those particular frequencies!

There's an amazing scene in the 2013 movie Man of Steel, where Superman, as a young boy, discovers he can see not just visible light, but ultraviolet and even x-ray light. It's so much information that it becomes overwhelming and scary. And yet, when he learns to control it, to filter it, the ability becomes incredibly useful.?

Here in the real world, doctors and scientists and astronomers have developed instruments that can similarly be tuned to any specific level of electromagnetic energy — allowing us to "see" it. The results include unbelievably detailed images of faraway galaxies, and scans that peer inside your body.

It makes me wonder: what else is there just outside our everyday senses? What could you learn about your world if you could twist a dial and pick up other stations? What signals are hiding, waiting to be discovered?

Holding it Together

In order to have your mind blown, sometimes you have to go back to basics. So… you'll remember from science class that everything is made of molecules, and molecules are made of atoms. Every atom has one or more protons and electrons. And the electrons are kind of flying around the protons in the nucleus, and it all holds together because electrons have a negative charge and protons have a positive charge, so they're attracted through magnetism.

But what powers magnetism? Why do negatives and positives attract??

And here is where it gets really weird. Because the answer is light.?

Photons, the essential energy packet of light, are the force carriers of electromagnetic reactions. That means that the electron and the proton each exchange photons with each other, like passing notes in class saying let’s stick together. And two electrons literally pass light signals to each other saying, "dude, stay away." And it’s all done with light.

So you have about 7 million billion trillion atoms in your body right now (I'm not making that up)… what’s keeping them all togther? Light. Light is produced, light is exchanged among the atoms. Not visible light, of course, but incredibly small packets of photons, carrying energy and information.

Light truly holds the universe together.

Richard Feynman, who won a Nobel prize from his work explaining all this in a theory called quantum electrodynamics (QED), was careful to explain that no one knows why this stuff works. Nevertheless, it does.?

Swimming in Light

You're glowing. No, seriously, you're literally glowing right now. Every cell in your body is generating heat, and some of that is being thrown off as a bit of light. In order to understand this, you have to know that the light we see ("visible light") is just a tiny sliver of the full spectrum of light around us. Other kinds of light include infrared light (which we experience as heat), microwaves (good to cook with), x-rays, and even radio waves. These are all exactly the same thing as the light we see, but with more or less energy.

Now, here's the amazing thing: Everything that has any temperature emits infrared light. Any temperature! Take an ice cube out of the freezer and it’s glowing with light. And because everything in the universe has at least some temperature, everything in the universe, just by existing, emits light. Can’t help it.?

And that includes you. We literally glow like lightbulbs, radiating infrared light.

We are all awash in a sea of never-ending light, emanating from every thing, every direction. That we cannot see most of the light doesn't mean we're not swimming in it.

Light it Up!

Technically, there are two ways to create light: incandescence and luminescence. The former comes from heating a material, such as the nuclear reactions in the sun, or from electricity passed through a tiny wire filament inside an incandescent lightbulb until it glows, white-hot at over 2,000°F.

But luminescence is even more fascinating: it's light without heat. There are many different kinds of luminescence, including:

• Bioluminescence: Some organisms generate their own light, literally from within. For example, a firefly generates bioluminescence with a chemical reaction inside its abdomen. Marine biologists now estimate that about 90 percent of ocean animals living below 500 m (1640 ft) are bioluminescent.?
• Phosphorescence: You know that "brightener" listed in some laundry detergents? It makes white clothes "whiter" because the phosphorous chemical in it literally glows with cool, visible light when energy from the sun hits it. Similarly, laundered white shirts and socks, natural phosphors in your teeth, and fluorescent paint all pop out brightly under an ultraviolet "black" light because they respond to the energy by giving off light we can see. And fluorescent lightbulbs glow because the inside of the glass is coated with phosphorescent chemicals that radiate when you pass electrical energy through them.
• Triboluminescence: If you chew a Wint-O-Green Life Saver in a dark room, you can experience triboluminescence — generating light from crushing, rubbing, ripping, or scratching. All hard candy emits light when broken, but because wintergreen oil (methyl salicylate) is fluorescent, it converts the generated ultraviolet light into blue light that is easy to see. Similarly, if you quickly pull open a Band-Aid wrapper, or a piece of cloth friction tape from a roll in a dark room, you'll see a thin line of light appear. Pulling off a strip of Scotch tape (cellotape) rarely generates visible light, but it creates X-rays so powerful that they can leave an image on dental photographic paper.

One last factoid that I can't resist including:

Some of our own human cells (including neurons in our brain) also appear to generate a small amount of light — not from heat, but through a form of bioluminescence. We currently don't know why, but neuroscientists now think cells may be using light to communicate with each other. It's possible that these "biophotons" allow cells to pass signals to their neighbors at a quantum level, leading some scientists to speculate that light may be a key mechanism behind consciousness.

Thank You!

I enjoy sharing my musings… and I enjoy hearing yours! Please share this newsletter with a friend,?follow me on LinkedIn, and send me feedback. You can always reach me at [email protected]