Every morning, after battling the snooze alarm, I peek through the curtains to see the first rays of sunlight coming over the horizon. I have always thought it amazing that those photons of light that start my mornings originated some 93 million miles away, traveling from our sun to reach my still sleep blurry eyes. Here are the five essential things you need to know about light.
1. Light acts like a wave, much like the waves when you throw a rock in a pond. These ripples have their own properties like height (called amplitude) and speed. They also have a frequency, which is the number of ripples that pass a set point in a certain period of time, and a wavelength, which is the distance between the tops of each wave.
2. Waves, like our ripples, have to have a physical medium (like water or air) to travel through. Light makes it’s own medium by creating an electromagnetic field, allowing it to travel through the vacuum of space.
3. While we rarely think about it, light can act differently depending on that electromagnetic field. Some light acts as microwaves that heats my morning water for tea, or as an x-ray that my dentists uses to tell me: “No cavities, but you still need to floss!”.
4. Everything we come in contact with produces an electromagnetic wave, some we can see like the reddish glow from hot coals on the BBQ grill and some we can’t see without using special cameras. In other words, everything produces some form of light even if we can’t see it.
5. The part of the electromagnetic field we can see, we call visible light. As the morning light reflects off my cat, the light enters my eyes and my brain puts the patterns together so I “see” the furry lump curled up against my legs. In the absence of any light, we would see nothing and everything would be black.