If the weak force were much smaller than it is, the neutrinos would escape quietly, the star would not explode, and the heavy elements would stay inside. If the weak force were much stronger, the neutrinos themselves would not be able to escape from the star, we would again have no explosion and no heavy elements would escape. So if the weak force were much different than it is, there would be no heavy elements outside the stars. Consider one more crucial balance. The reason is that the positive and negative electromagnetic charges occur in equal numbers, so that at large distances they cancel each other out.
Scientists don t know.
The main negative charge is the electron, a very small particle compared to the proton, the main positive charge. In fact, the numbers of electrons and protons left over must have been the same to within one part in 10 to the 37th power. If this had not happened, our universe would be dominated by electromagnetism instead of gravity, and there would be no life as we know it. In summary, it appears that very slight changes in the strength or balance of these force gives a universe which will not support any life we can imagine. The simplest explanation is that we live in a designed universe.