-
400 BCE
contributions of Democritus
The theory of Democritus held that everything is composed of "atoms" which are physically, but not geometrically, indivisible; that between atoms, there lies empty space, that atoms are indestructible, and have always been and always will be in motion that there is an infinite number of atoms and of kinds of atoms, which differ in shape and size. Of the mass of atoms, Democritus said, "The more any indivisible exceeds, the heavier it is." However, his exact position on atomic weight is disputed. -
isaac newton
Isaac newton theorized a mechanical universe with small, solid masses in motion. -
John Dalton
Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass. -
Albert Einstein
Einstein also in 1905 mathematically proved the existence of atoms, and thus helped revolutionize all the sciences through the use of statistics and probability. Atomic theory says that any liquid is made up of molecules (invisible in 1905). Furthermore, these molecules are always in random, ceaseless motion.