Bits of Light

Just as a few of my ancestors were traveling across the Atlantic Ocean to form a new life in the American colonies and the Great Fire of London was raging, Isaac Newton’s corpuscular theory of light was shaping up.

This idea helped to explain a lot of things about light, like the way it bounced off of mirrors, or the way it seemed to slow down in a different medium (refraction). If you could imagine uncounted tiny particles flying through the air (or space), you could envision and predict a lot of the behavior of light.

More than two centuries later, these photons were finally accepted as real by the scientific community, although the word real is doing a lot of heavy lifting here. There’s a really good analogy you’re probably already familiar with: the computer bit.

The bit is the smallest amount of information you can possibly have. The name itself is one of those portmanteaus like brunch or zompire, deriving from the words binary and digit. Binary implies that there are only two decisions to be made: yes or no, one or zero; digit means number.

So, this represents the smallest decision you can possibly have. It’s just yes or no, which—if you’ve ever played the game 20 questions, you know you can find the answer to just about anything with yes or no questions, given enough questions.

Photons are like bits of light. Like a bit, they’re all exactly the same—interchangeable in every imaginable way, like the US dollar: it spends the same no matter what you buy.

And, like dollars, photons can be used for a wide variety of tasks.

If you can see, you can thank photons. Imagine infinitesimally tiny particles constantly bombarding your eyeball. These particles go all the way to the back of your brain, where your optic nerve creates an electrical pulse—another binary signal.

This is called transduction, and it happens with every one of our sensory inputs. This is like when a computer “sees” an image, encodes this information into ones and zeroes for easy storage and transmission, and then sends those ones and zeroes along to someone else. At the other end, the image is recreated for someone else to see.

That’s pretty cool, but the light we can see only represents a minuscule fraction of what the glorious photon can do. Besides all the visible light, you probably already know that microwaves, gamma rays, and radio are all the same thing: just photons zipping through whatever medium they’re in—even no medium at all.

So, they carry light and information, but what else?

Heat, for one thing. Infrared light is a collection of these same photons, but when these photons hit your skin, they make it jiggle. Jiggling and temperature are synonyms at the atomic level, and temperature is just a way to measure all that jiggling.

In the same way that your optic nerve makes sense of the signal, so do the nerves in your skin as you warm up.

You know what else those bits of light can be used for? Magnetism.

Okay, maybe this one’s less surprising, since you already know electricity and magnetism are manifestations of the same force. Still, it’s really cool to understand that the same little particles that paint a moving picture for you also make a magnet pick up a nail, and other interesting things.

These incredibly versatile bits of light are everywhere around us, and they’re doing all kinds of things to our world all the time.