Are Fermion Masses Like Planetary Orbits?
A more and more common argument one hears from string theorists these days (for one version see a recent anonymous comment posted here) goes more or less like this: “A fundamental theory shouldn’t be expected to predict things like fermion masses or the standard model gauge group anymore than it should be able to predict the physical properties of the planets. Anyone who expects this is making the same mistake as Kepler, who tried to relate Platonic solids to planet orbits.” The idea here is that many or even all of the things we don’t understand about the standard model are not fundamental aspects of the theory we should expect to be able to predict. Perhaps they are determined by the details of the history of how we ended up in this particular time and place, just as the properties of the planets were determined by the detailed history of the formation of the solar system. As far as we can tell, the properties of the standard model hold uniformly throughout the observable universe, s
