1 - Review of quantum physics and atomic theory

Abstract

Understating modern theories of solid-state physics is only possible if we understand quantum mechanics and its applications at the atomic levels. Therefore, this chapter presents the evolution of quantum physics and the chronological overview of the attempts to understand the microscopic picture of the atomic structure. Historically, the roots of atomic physics lie in many thought experiments, which believed that matter is made of tiny indivisible constituents called atoms. One of the oldest references in this context lies in the Indian philosophy by Maharishi Kanad in one of his books, “Vaisesika Sutra,” which propounded the matter as consisting of indestructible particles of indivisible paramanus (the atoms). He believed that these paramanus have their unique identity and specific properties. This idea was further advocated by Democritus, a Greek philosopher, who put forward the theory of the atomic universe (460–370BCE), which states that the world is made of hard (indestructible) indivisible particles (called the atoms) of matter moving through the empty space. The word atom is taken from the Greek word atomos means, literally, “uncuttable,” This thought-based hypothesis of the atoms was first supported experimentally by John Dalton in 1804, who demonstrated that the atoms are indestructible, indivisible, and alike for the same element. This is the first theory proposed on the experimental observations. These theories come over a wide gap of time but established the same concept that there are some indivisible constituents of matter. Another fact associated with the atoms was their charge neutrality.