The quest to understand where atoms end

‘Atoms’, a student of the English chemist Henry Enfield Roscoe asserted in the late 19th century, ‘are round bits of wood invented by Mr Dalton.’ He was referring to the models created for John Dalton to illustrate the atomic theory described in his 1808 book A New System of Chemical Philosophy. Dalton made concrete (or rather, wooden) the centuries-old idea that all matter is composed of fundamental and indivisible particles, arguing that these invisibly small building blocks combine in fixed and generally simple proportions to make molecules.