> Perhaps the notion that the subatomic world is as vast as the universe, as stated by Richard Feynman when he said "There’s plenty of room at the bottom.", holds more truth than we realize.
That's true and he knew this even at the time of this famous lecture. He was talking about that there is a plenty of room at the room for us to explore how can we use atoms in synthetic chemistry not into exploring the fundamental particles inside them . When we are talking about particle physics we are basically talking about the successor field of nuclear physics. It studies the interactions and particles inside the sub-atomic structure. Feynman's most interesting work - parton model- was one of the first innovative theoretical work in QCD and was one of milestone of development and validation of the quark model.
The idea that protons, neutrons, and other hadrons are composed of fundamental particles called quarks that come in six -flavors- (up, down, strange, charm, top, and bottom) and possess fractional electric charges. These quarks are bound together by the strong nuclear force, mediated by particles called gluons, and must combine in specific ways to form observable particles (mesons or baryons). One day this was a wild theory and needed a lot of work on validating this model experimentally.