• It made the electromagnetic field up of particles called photons.
  • The strong nuclear field that holds protons and neutrons together? Made up of particles called gluons.
  • Is the weak nuclear field responsible for radioactive decays? Made of particles called W-and-Z bosons.
  • We can use these terms of particles and fields interchangeably in QFT because the quantum fields themselves encode all the information for everything. Have a particle and antiparticle annihilating? Equal-and-opposite excitations of a quantum field describe that. Want to tell the spontaneous creation of particle-antiparticle pairs of particles? That’s also because of excitations of a quantum field.
  • Every particle in the universe is a ripple, excitation, or bundle-of-energy of the underlying quantum field. Even particles themselves, like electrons, are just excited states of a quantum field. This is true for the quarks, the gluons, the Higgs boson, and other Standard Model particles.
  • Every excitation that’s possible has a reverse excitation that’s also possible, which is why this theory implies the existence of positrons (antimatter counterparts of electrons). In addition, photons exist, too, as the particle equivalents of the electromagnetic field. They interact; they transfer energy and momentum and angular momentum; excitations come and go.
  • When we take all the forces that we understand, i.e., not including gravity, and write the QFT version, we arrive at the Standard Model predictions.
  • The six (up, down, strange, charm, bottom, top) quarks and their antiquark counterparts.
  • The three charged (electron, muon, tau) and three neutral (electron neutrino, muon neutrino, tau neutrino) leptons, and their antimatter counterparts,
  • The eight gluons (because of the eight possible color combinations),
  • The two weak (W-and-Z) bosons,
  • The one electromagnetic (photon) boson,
  • And the Higgs boson.
  • The quarks and leptons are fermions, so they have antimatter counterparts. The W boson comes in two equal-and-opposite varieties (positively and negatively charged), but there are 24 unique, fundamental excitations of quantum fields possible.
  • So what about complex systems like protons, atoms, molecules, and more? You understand that just as the 24 fields are excitations of the underlying QFT that describes our physical reality, these complex systems are more than just combinations of these fields put together into some stable or quasi-stable bound state. Instead, it’s more accurate to view the entire universe as a complicated quantum field that, itself, contains all the physics. Quantum fields can describe an arbitrarily large number of particles that interact in all ways our theories can conceivably allow. And they do this not in some vacuum of space but amidst a background of not-so-empty-space, which plays by the rules of QFT, too.
  • Reality differs from our classical picture of a smooth, continuous, well-defined universe. Particles, antiparticles, and many excitations of the fields are constantly being created-and-destroyed. Although these quantum fields indeed began as a mathematical construct, they describe our physical, observable reality more accurately than any other theory we’ve concocted. They allow us to make exact predictions about what the results of an experiment involving the quanta of the Standard Model will yield: predictions every experiment sensitive enough to test them have borne that out.