AMA | October 2024

14149.493 - 14168.708 Sean Carroll

But certainly the simplest, most direct thing to say, and maybe they knew this from measurements of the mass of the particle, I don't really know— But certainly the simplest thing to say would be all of the three quarks are in exactly the same quantum state with their spins aligned. OK, the same kind of quark, same spin, et cetera. That is ruled out by the Pauli exclusion principle.