The Neutrino

by Jack Holt

There are two categories of subatomic particles that comprise all the matter in our universe: quarks and leptons. This theory is called the Standard Model of Particle Physics and it can be used to describe the particle make-up of everything in our known universe. 

Quarks make up the protons and neutrons inside atoms and come in 6 different types or “flavours”, the combination of these flavours corresponds to what it makes up (and yes, the official scientific definition for different types of subatomic particles in quantum physics is “flavours”). The only other variation of a quark is when it interacts with the Higgs Boson (another particle in the model) to form the photon, which comprises all light in the universe. (In addition every particle within this model that I am about to talk about has its own antimatter counterpart that holds their own unique properties). 

Leptons also come in different flavours, including three flavours of electrons and three flavours of neutrinos. The three flavours of neutrinos are the electron, muon and tau neutrinos which all interchange with one another as they travel, this process has been named neutrino oscillation. Neutrinos were discovered in 1956 and are the most abundant particles, that have mass, in our universe (there is a greater population of photons, however they are massless particles). For reference, our sun produces ~10^38 neutrinos every second, that's 1,000,000,000,000,000,000,000,000,000,000,000,000,000 particles being emitted every single second from the sun’s surface and this will continue for the billions and billions of years that it continues to shine. Every time atomic nuclei come together or split apart, they produce neutrinos. This means a nuclear reaction is required like the one within our sun; however, this can be so small that even the potassium in a banana emits neutrinos. These subatomic particles are electrically neutral and because their resting mass is so small it was thought to be zero until 2015 when Takaaki Kajita and Arthur McDonald experimentally proved they had mass, a hugely impactful discovery in the fields of quantum and particle physics. Furthermore, in spite of being extremely abundant, neutrinos almost always pass through normal matter unimpeded, but there is an extremely small chance that they interact with their corresponding ‘electron’ particle (electron, muon or tau), this is deemed The Neutrino Event and is incomprehensibly rare. To put this rarity into context, 100 trillion of these neutrino particles pass through your body every second! Yet the probability of one ever interacting with one of the seven billion billion billion particles in your body, is only 1 in 4. The interaction is so small that it has absolutely no impact on your body and causes absolutely no harm to your health. 

Despite their mysterious magnificence, this is the reason that neutrinos have taken so long to be discovered.