The gravitational interaction alone governs the motions of the planets around the sun. Why are the other fundamental interactions not significant in planetary motion?


No particle of fractional charge has yet been observed. If none is found in the future either, does this necessarily mean that the quark hypothesis is wrong?

The Bohr Theory permits us to visualize the structure of the atom, whereas quantum mechanics is very complex and concerned with such ideas as wave functions and probabilities. What reasons would lead to the replacement of the Bohr Theory by quantum mechanics?

Thank you for any assistance available!

The gravitational interaction alone governs the motions of the planets around the sun. Why are the other fundamental interactions not significant in planetary motion?

Strong nuclear interaction, electromagnetic forces, weak nuclear interaction. Distances for these interactions are too great as the force drops off rapidly with distance.



No particle of fractional charge has yet been observed. If none is found in the future either, does this necessarily mean that the quark hypothesis is wrong?


I don't know. That's outside of my field of expertise.


The Bohr Theory permits us to visualize the structure of the atom, whereas quantum mechanics is very complex and concerned with such ideas as wave functions and probabilities. What reasons would lead to the replacement of the Bohr Theory by quantum mechanics?

The Bohr theory doesn't explain all of the observations. The Heisenberg uncertainty principle is incompatible with the Bohr theory. There are others.