A long time ago, the scientist Ptolemy was trying to understand why the planets move the way they do. He knew that things in the sky orbited around the Earth, basically. And he knew that things in the sky moved in circles. However, his observation of the planets did not match with the idea of an Earth in the center with orbiting bodies above. So, he figured out that the planets must be riding on disks that rotate, with the center of the disks rotating on the main disk holding the earth. These were epicycles that allowed Ptolemy to have his observations and at the same time keep his immutable principles. More here.
Not quite so long ago, the scientist Bohr was trying to understand the nature of matter. He hypothesized that atoms were made up of descrete subatomic particles. One of these were electrons, which orbited a nucleus. The Bohr model of the atom is the model that the non-scientists in the room know. More here & here.
The trick is both guys were wrong. Sure, in both cases the hypothesis had some support from observation. But an electron is not a ball bearing spinning around a center. Here’s a bit from Wikipedia that matches my limited knowledge of physics:
According to quantum mechanics, electrons can be represented by wavefunctions, from which a calculated probabilistic electron density can be determined. The orbital of each electron in an atom can be described by a wavefunction. Based on the Heisenberg uncertainty principle, the exact momentum and position of the actual electron cannot be simultaneously determined. This is a limitation which, in this instance, simply states that the more accurately we know a particle’s position, the less accurately we can know its momentum, and vice versa.
The curious thing is that Bohr’s model is/was very helpful. It furthered human understanding of the natural world, while Ptolemy’s was not helpful. It hindered movement toward the more accurate description of the natural world. Was there a fundamental difference in their methods?