What Is Light

Over the centuries, our view of light has changed dramatically. The first real theories about light came from the ancient Greeks. Many of these theories sought to describe light as a ray -- a straight line moving from one point to another. Pythagoras, best known for the theorem of the right-angled triangle, proposed that vision resulted from light rays emerging from a person's eye and striking an object Light is part of the electromagnetic spectrum, which ranges from radio waves to gamma rays. Electromagnetic radiation waves, as their names suggest are fluctuations of electric and magnetic fields, which can transport energy from one location to another. Visible light is not inherently different from the other parts of the electromagnetic spectrum with the exception that the human eye can detect visible waves. Electromagnetic radiation can also be described in terms of a stream of photons which are mass less particles each travelling with wavelike properties at the speed of light. A photon is the smallest quantity (quantum) of energy which can be transported and it was the realization that light travelled in discrete quanta that was the origins of Quantum Theory. It’s a kind of energy called “electromagnetic (EM) radiation” (but this kind of radiation is not harmful, except for occasional sunburn). There are other kinds of EM radiation too (radio waves, microwaves, x-rays, etc.), but light is the part we can see, the part makes the rainbow.