What Is Light

Light, simply put, is energy. It is how energy moves through space. Not so simply put, light is electromagnetic radiation. Visible light, that we are used to referring to, is only a sliver of the electromagnetic spectrum. The portion of the spectrum that we can see is approximately at the center. Below visible light in the spectrum lies infrared, micro and radio waves which have shorter frequencies. Above visible light is ultraviolet light, “x” rays and gamma rays which have higher frequencies.  Light bends the rules of physics by having properties of both a particle and a wave. 

Light can be described as a particle because it can be represented by a photon, or quantized amount of light energy. How much energy it contains determines where in the electromagnetic spectrum it resides. However, Light has other properties that allow it to be categorized as a wave also.

It is more difficult to think about light in this way but comparing it to sound waves helps.

When two different notes are played on a piano at the same time, the only difference between the sounds are the frequencies that the vibrating strings are producing. The higher the note, the higher the frequency and the shorter the wave lengths. When observed in this context light works virtually the same way. The higher the energy (frequency) inside the photon the highers that photon belongs on the light spectrum. Different levels of energy, inside a photon, produce different colors. If this description isn't helpful for you perhaps this example will: if you turn the light on in the hallway and a bedroom door is slightly ajar how does the light enter the room? The light spreads out. Even though the door is only open an inch or two you can see much more than you would think. If light did not act like a wave then you would only be able to see an area of equal proportions to the ajar door. This is known as diffraction. This phenomenon is what makes light an “X” factor in the universe.