Niels Bohr and Randell Mills
The history of efforts to elucidate a physical model of the extremely small is ancient. The two opposing schools were particle and aetheric. At different times, it was generally believed that extremely small pieces comprised everything or everything was made of some materia prima. This historical sequence is a fine way to tour the way people came to understand what could never be examined directly with the senses on the smallest scale of size. In 1913, Bohr introduced his model of the atom, which gave us the well known image that everyone has when picturing an atom. However impossible it was, it was so useful. It was a big step forward toward making sense of line spectral data that had been empirically fit with the Rydberg formula that matched at least for hydrogen. Rydberg's formula was not developed from first principles. It was a curve fit to the data. That made it theoretically unfounded, and so vast efforts went into finding some way ...