history of particle physics
the idea that our universe is composed of individual elementary particles dates back to 6bc. this was studied by ancient greek and indian philosophers, muslim scientists, and early modern europe physicists. in the 19th century, john dalton concluded that each element was composed of one unique type of particle, and named them atoms, meaning indivisible.
near the end of the 19th century, physicists discovered that the atom was not the smallest particle in the universe. between 1879 and 1897, the electron was discovered and its charge measured. By 1914, experiments established that the atom was composed of a dense positively-charged nucleus and surrounding electrons with smaller masses. the name proton was given in 1918 when it was discovered that the hydrogen atom was a positively charged particle with no electrons. the discovery of isotopes with the same atomic number but different masses prompted the naming of uncharged particles, the neutron. the force by which neutrons attracted each other became known as nuclear force. investigations of nuclear fission and fusion became possible in 1939 with these discoveries.
it was then established that all electrons were identical, confirming the existence of identical particles. under the spin-statistics theorem, all particles in the universe were determined to be either a boson or a fermion. the forces governing the distinction between these two kinds of elementary particles led the the proposal of quantum field theory, nowadays used to construct physical models of subatomic particles.
