Gardner Variety: the mysteries of light
So, early heads up: This column might be a little odd. It’s also part one of a two-part column concluding next week.
Let’s have a little chat about electromagnetic radiation. The term sounds complex, but it’s really just a fancy way of referring to light.
Light is everywhere. It drives everything. It drives photosynthesis, producing the oxygen we breathe. Light is the x-rays doctors use to detect broken bones. It’s the radio waves zipping through the air, allowing us to listen to music through an antenna. It’s the microwaves we use to reheat that old pasta that’s been sitting in the fridge for a week.
These are all different forms of light, travelling at the exact same speed throughout the entire universe. The only thing that differentiates one from the other is its wavelength, or level of energy.
When considering light, it’s best to begin by thinking of the light source — i.e. the sun, a lamp, a candle. Everything we see as humans is defined by a very small portion of the electromagnetic spectrum commonly referred to as visible light, which contains all of the colors detectable to the human eye. In fact, light waves, before they touch or interact with an object, contain each of these colors simultaneously.
Let’s take a closer look at what’s really going on here.
Imagine a plump, red apple. We don’t see the apple as red because the apple is inherently red. Rather, we see the apple as red because its physical makeup and energy cause it to absorb each color in the visible light spectrum aside from red. The apple appears red because it is reflecting the only color it didn’t absorb to our eyes.
If I lost you, bear with me for just a little while longer. This concept should be a little easier to grasp for all my Pink Floyd homies out there. Picture the iconic Dark Side of the Moon album cover. On it, you see a single triangular prism in front of a solid black background. From the left, a beam of light shines directly through the prism, causing the visible light spectrum — essentially a rainbow — to shine through the other side.
This strange phenomenon, first discovered by Isaac Newton, proves that light does, in fact, contain each color detectable to the human eye, and that everything we see is simply based on the colors a particular object reflects.
Visible light represents only a minute fraction of the electromagnetic spectrum, however, and this is where things really get cool.
In order from the highest amount of energy emitted to the lowest, the electromagnetic spectrum consists of cosmic rays, gamma-rays, x-rays, ultraviolet rays, visible light, infrared rays, microwaves and radio waves. Each of these are fundamentally the same. They are separated only by their wavelengths, which determines their energy.
Radio waves transmit music, conversations, pictures and data — all encoded as continuous sine waves — through the air, often over millions of miles. Microwaves allow us to reheat food using heat primarily created through the absorption of the energy in water.
Infrared rays are used in night vision equipment when there is insufficient visible light to see. Remember the alien from “Predator” Arnold Schwarzenegger barely managed to best? He wrought havoc on the humans because the light his species’ eyes could detect fell within the infrared spectrum.
Astronomers use each of these forms of light when creating telescopes to produce the most accurate depiction possible of the universe. Point being, light is everywhere. It shapes everything. It’s pretty awesome.
Tune in next week for part two. It’s about to get all philosophical up in here.