Fermions & Bosons
All elementary particles in physics are classified as either fermions or bosons. Quantum physics demonstrates the particles may have an intrinsic non-zero "spin," or angular momentum, associated with them.A fermion (named after Enrico Fermi) is a particle with a half-integer spin, while a boson (named after Satyendra Nath Bose) is a particle with an integer spin. These spins result in different mathematical applications in certain situations, which is far beyond the scope of this article. For now, just know that the two types of particles exist.
Simple mathematics of adding integers and half-integers show the following:
- Combining an odd number of fermions results in a fermion (because the total spin will still be a half-integer value)
- Combining an even number of fermions results in a boson (because the total spin will now be an integer value)
Basic Particles of Nature
Most people are familiar with the following particles, all of which are composed of still smaller objects, so I'll not spend much time addressing them here:- Atom - the basic chemical building block of matter, atoms are composed of electrons, protons and neutrons.
- Molecule - a complex structure composed of multiple atoms bonded together.
- Proton - a positively-charged particle that resides, typically, in the nucleus of an atom
- Neutron - a particle with no electrical charge that resides, typically, in the nucleus of an atom
- Electron - a negatively-charged particle that circles atoms and can be transferred from one atom to another
Breaking It Down: Quarks & Leptons
The two basic constituents of matter are quarks and leptons. Both of these subatomic particles are fermions, so all bosons are created from an even combination of these particles.Quarks are fundamental particles which interact through all four of the fundamental forces of physics: gravity, electromagnetism, weak interaction, and strong interaction. Quarks always exist in combination to form subatomic particles known as hadrons. Hadrons, just to make things even more complicated, are divided into mesons (which are bosons) and baryons (which are fermions). Protons & neutrons are baryons. In other words, they are composed of quarks such that their spin is a half-integer value.
Leptons, on the other hand, are fundamental particles that do not experience strong interaction. There are three "flavors" of leptons: the electron, the muon, and the tau. Each flavor is composed of a "weak doublet," which is the aforementioned particle along with a virtually massless neutral particle called a neutrino. Thus the electron lepton is the weak doublet of electron & electron-neutrino.
A Note on Structure
It can be hard to keep all these names straight, so it might be helpful to think of the animal world, where such structured naming is more natural to us. Humans are primates, mammals, and also vertebrates. Similarly, protons are baryons, hadrons, and also fermions.The only difference is the terminology which is, unfortunately, confusing because the classifications tend to sound similar to each other. Confusing bosons and baryons, for example, is far easier than confusing primates and invertebrates.
