Everything in the universe that occupies space is considered matter. All matter is classified as being a solid, liquid, gas or plasma (very hot ionized gases) depending on its physical state. Each of these states of matter is characterized by different physical properties. Critical phenomena relates to the physical properties of matter that occur at the phase transition points and specifically at the critical points.

While the first theories of matter were proposed by the ancient Greeks as early as 500 B.C., it was not until the nineteenth century that the modern understanding of matter was proposed. At this time, English chemist John Dalton (1766- 1844) introduced the atomic theory that postulated that all matter is composed of individual particles called atoms. He also suggested that various atoms exist with different masses and sizes to make up all of the known elements. Today, it is known that...