In a paper published in 1672, the British scientist Sir Isaac Newton hypothesized that light consists of a stream of tiny particles. Around the same time, a Dutch physicist by the name of Christian Huygens hypothesized that light behaves like waves. Today, both theories are considered to be applicable.
Light is believed to have characteristics of waves and particles.
In this general introduction to light and color we will consider the wave aspect of light. We experience two main types of waves, longitudinal and transverse, both of which carry energy. Sound waves are an example of longitudinal waves, waves in which the medium waves parallel to the direction of the wave. This can be demonstrated by tugging on a slinky that is being held still at one end. Light waves are an example of transverse waves.