What is a fundamental particle?

Fundamental particles are point like particles that are not made up from any constituent parts. Or at least, we have no evidence to prove this wrong. Fundamental particles are also known as elementary particles – you may hear this term also being used. Particles are put into categories in order to distinguish them and the two categories I will be introducing are leptons and quarks.

LEPTONS

leptons

You’ve probably heard of the electron, right? It’s the particle that orbits around the nucleus in an atom. All the rest in the list above are probably brand new to you. After the electron was discovered two more particles very similar to the electron were discovered but had a mass 200 times heavier and 3500 times heavier than the electron and this was the muon and the tauon respectively. In particle physics we call these the second and third generations of the electron. All three particles still have a negative electric charge which is indicated by the negative power.

All neutrinos are created as a by-product in radioactive decays and have near to zero (but not quite zero) masses. All three neutrinos have zero electric charge.

QUARKS

quarksYou may not of heard of quarks before but they combine together in different ways to make up larger particles called hadrons. Hadrons are a classification of particles two of which are protons and neutrons, the particles that make up the nucleus of an atom. The same principle applies with the first, second and third generation of the quarks – they get more massive as you move up generations.

The up particle and its second and third generation are all positively charged. The down particle and its second and third generation are all negatively charge. In the two blog posts linked I go into more detail on how the charges on these particles work. What’s inside protons and neutrons? – Different Types of Hadrons

How do we know these are fundamental particles?

Because, so far, we have not been able to split them apart! Particle accelerators like CERN have tried their hardest to split apart the particles but the more energy they put into doing so the more particles they create. Everybody knows the famous equation e=mc2 . This means that energy and mass are interchangeable, the energy put into the collisions is simply turned into mass and new particles are created.

Why are there different generations and what do they do?

The first generation particles are the least massive particles. This means they cannot decay into any other particles and are classed as stable.

The second and third generation particles are classed as unstable and decay to a lower generation almost immediately in order to free energy/mass (e=mc2). By decaying to a lower generation the particles mass is turned into energy and other particles are created out of the energy.

We don’t know exactly why there are different generations.

Are bosons not fundamental particles?

Yes, bosons are also classed as fundamental particles but they are also charge carries. I’m leaving that topic for another blog post as they don’t have generations like the other fundamental particles do.

 

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