 The weak nuclear force, or weak interaction, is responsible for radioactivity, for example beta radiation ejecting electrons and neutrinos. It's the force that turns a neutron into a proton. Unlike quantum electrodynamics and quantum chromodynamics, there is no separate matter field that creates a particle with a weak force charge, sometimes called weak isospin or weak hypercharge. Instead, all fermions already have this charge, including electrons, quarks and neutrinos. Like accelerating electrons and quarks create vibrating ripples in their respective force fields called photons and gluons, accelerating electrons, quarks and neutrinos can create vibrating ripples in the weak hypercharge field called z-particles, and where photons can accelerate electrons and gluons can accelerate quarks, z-particles can accelerate neutrinos and electrons and quarks because they all carry the weak charge. But for the weak hypercharge, there are two additional particles called w- and w-plus. Like the gluon carries color charge, w- carries a negative electric charge equal to the charge of an electron, and w- carries a positive electric charge equal to the charge of a positron. The z-particle has no charge at all. They are all spin-1 particles making them bosons. They are the force particles for the weak interaction. Just like the photons and gluons can create matter-antimatter particle pairs, the w- and z-bosons can create matter-antimatter particle pairs, and like interacting electrons and quarks disturb their respective force fields, creating virtual photons and gluons that exerts the force of their fields, interacting particles carrying the weak hypercharge, disturb the weak hypercharge field, creating virtual w- and z-bosons that exert the force of the field. The force can be attractive or repulsive depending on a variety of circumstances. We call it the weak force because its coupling constant is 3.3 million times smaller than the strong force coupling constant. And unlike massless photons and gluons, these particles are massive, around 50 times more massive than an up quark, and 160,000 times more massive than an electron. This makes the range of the weak force around one-tenth of one percent of the diameter of a proton. All the force particles actually exert a force on their respective matter particles, but the weak force has a unique additional capability. It can change one flavor of quark into another, or one type of lepton into another. The idea that a force field particle can cause a matter field particle to decay, i.e. transform into another particle, was a new one. We'll use beta decay from our radium to polonium energy experiment to help illustrate how this works. The process consists of two phases. The first phase is similar to the way an electron emits a photon when it drops to a lower energy state in an atom. Here a down quark drops to the lower energy up quark and emits a W boson that carries away the energy and a full unit of electric charge. The remaining quark's charge then goes from minus one-third to positive two-thirds making it an up quark. However, the mass of the weak field quantum is so large that there is not enough energy in a down quark quantum leap to an up quark to create a fully independent W boson. Instead, what is created is a virtual W boson. However, in the second phase, because there is enough energy in the virtual boson to create an electron and a neutrino, it decays into these particles. This is possible because both the electron and the neutrino carried the weak hypercharge. This is how our radium turned into polonium in our segment on the atom. Because of the significant amount of energy needed to produce these massive Z and W weak force bosons, it wasn't until 1972 that the first evidence for Enrico Fermi's weak interaction theory was found. This event shows a neutrino-electron interaction that would require a Z boson. It was recorded by the Gargamel bubble chamber at CERN. Final proof came for Z and W bosons when the proton anti-proton collider was built at CERN in 1983.