Is plasma considered a fourth form of matter?
crackers says: There are three classic states of matter: solid, liquid, and gas; however, plasma is considered by some scientists to be the fourth state of matter. The plasma state is not related to blood plasma, the most common usage of the word; rather, the term has been used in physics since the 1920s to represent an ionized gas. Space plasma physics became an important scientific discipline in the early 1950s with the discovery of the Van Allen radiation belts. Lightning is commonly seen as a form of plasma.