Matter commonly exists in four states (or phases): solid, liquid and gas, and plasma. However, advances in experimental techniques have revealed other previously theoretical phases, such as Bose–Einstein condensates and fermionic condensates. A focus on an elementary-particle view of matter also leads to new phases of matter, such as the quark–gluon plasma. For much of the history of the natural sciences people have contemplated the exact nature of matter. The idea that matter was built of discrete building blocks, the so-called particulate theory of matter, was first put forward by the Greek philosophers Leucippus (~490 BC) and Democritus (~470–380 BC).
How many phases of matter are there? What new phase of matter can be considered with a focus on elementary particles? What is the theory that matter is made up of discrete building blocks called? What colleague of Democritus, also a Greek philosopher, helped him propose the particulate theory of matter? People have been wondering about the nature of matter for the entire history of what branch of science?