Force force. Here the strong force acts indirectly, transmitted as gluons, which form part of the virtual pi and rho mesons, which classically transmit the nuclear force (see this topic for more). The failure of many searches for free quarks has shown that the elementary particles affected are not directly observable. This phenomenon is called color confinement. The weak force is due to the exchange of the heavy W and Z bosons. Its most familiar effect is beta decay (of neutrons in atomic nuclei) and the associated radioactivity. The word "weak" derives from the fact that the field strength is some
History of subatomic physics of fundamental interactions (see below) only. Because the quantum field theory (see above) postulates no difference between particles and interactions, classification of elementary particles allowed also to classify interactions and fields. Now a large number of particles and (non-fundamental) interactions is explained as combinations of a (relatively) small number of fundamental substances, thought to be fundamental interactions (incarnated in fundamental bosons), quarks (including antiparticles), and leptons (including antiparticles). As the theory distinguished "several" fundamental interactions, it became possible to see which elementary particles participate in which interaction. Namely: The next step was a reduction in number of fundamental interactions, envisaged