truthsharer –
20 years ago, the atom was the smallest thing known to man, now we know there are things smaller.
You are joking, right?! The first subatomic particle to be discovered was the electron in 1897. In 1900 the foundations of quantum mechanics (which deals with what happens at a subatomic level) were laid down by Planck (he of the constant fame) and the two main models that we work with nowadays were fully constructed by the late 1920s. The atom itself was split for the first time in 1917 (by Rutherford) and 28 years later the first a-bomb was detonated. In other words, people have known for a while that there was stuff smaller than an atom.