Perhaps you already know that 2015 is the official International Year of Light (and since the Universal Year of Light is 2533, I suggest you take your chance to celebrate the glory of light now). In honor of light, here is a list from Wired.com of the five fundamental properties of light that you should either already know or, at the very least, endeavor to learn. If you have any fun facts about light that you believe are equally essential, share in the comment section below the article.
1. Light is a wave.
If you throw a rock in a puddle, the water will ripple because the disturbance moves radially outward from where it began; the water molecules merely move up and down. A wave includes four properties: amplitude (the size of displacement from the disturbance), wavelength (the distance from one disturbance to the next measured in meters), frequency (the number of waves that pass a stationary point, measured in cycles per second or Hertz), and wave speed (the product of wavelength and frequency, measured in meters per second). As a wave, light can expand and radiate in all directions, interfere with other waves, bend around corners, carry energy and momentum, and interact with matter.
2. Not only is light a wave, it is an electromagnetic wave.
As such, light can travel without a medium. The rock thrown into the puddle created a wave that traveled through the water, its medium. Electromagnetic waves are essentially their own medium. A changing electric field makes a magnetic field and vice versa. Since electric field waves and magnetic field waves make each other propagate, they do not need another medium to exist.
3. Different wavelengths of light interact differently with matter.
The electromagnetic spectrum comprises radio, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays, from largest to smallest waves, respectively. All these electromagnetic waves travel at the speed of light, but they interact differently with matter. For example, while X-rays can pass through your skin, you (using visible light) cannot play Superman and see through said skin because visible light does not act that way with such matter. The interaction of light with matter depends on the frequency.
4. A human can see objects when light passes through the eye.
Light enters an eye in two ways: A light source (like a light bulb) creates light, which enters an eye and the brain interprets the signal as light; or, a light source reflects off an object and then into an eye. Without any light whatsoever, (which rarely happens,) an eye will see the color black.
5. All objects produce light (electromagnetic waves).
Objects often emit electromagnetic radiation in the infrared spectrum, preventing you from seeing it. If you have a handy infrared camera, the different colors will correspond to the different temperatures of the objects. Objects create shorter wavelengths as they grow hotter. The object could eventually look red or white as the shorter wavelength is produced and made visible to the human eye. Ultraviolet light could be produced at even higher temperatures.
There are the five fundamentals facts of light, according to Wired.com. If you learned something from this article or have more to share, comment below. Happy International Year of Light!