The view of the Standard Model on the β decay of neutrons through weak interaction is that neutrons break down to form protons P and weak bosons W^- and finally into protons, electron and anti-electron neutrinos. The three quarks (U,d,d) that compose neutrons are joined by strong interaction, so bonds formed by strong interaction supposedly cannot be broken by weak interaction, which is far weaker than strong interaction. Nevertheless, neutrons do decay. Further, the three quarks (U,d,d) that form neutrons are fundamental particles, and it should not be possible for other fundamental particles to emerge from these three fundamental particles. Nevertheless, not only does (U,d,d) change into (U,U,d), but electrons and anti-electron-neutrinos, which are fundamental particles, also emerge. This must not have a double meaning. As shown here, there are multiple contradictions in weak interaction of the Standard Model. In this paper, weak interaction is mediated by the π-ons group that results from the working of strong interaction step 1 that was described in a previous paper and acts on the nucleons group (P ,P ̅ ,n,n ̅ ) that resulted from step 2. In other words, at the point immediately prior to the emergence of weak interaction, all the particles that existed in the universe were used in order to make weak interaction emerge. The weak interaction in this paper refers to the strong interaction bonds composed of neutrons and π^±-ons first being dissolved by strong interaction. As such, the reason why neutrons change to protons is just because the d-quark of the neutron is replaced with the U-quark of the π^±-on.