At the end of Our Dynamic Universe, we considered big things like stars, galaxies and the Universe itself. Now the Particles and Waves unit brings us to particles so small we need groups of them just to make a single atom. Is there a connection?
Why do we study particles? from mr mackenzie on Vimeo.
The Standard Model
An elementary (or fundamental) particle is a particle that is not built from other, smaller particles. Until the start of the 20th century, scientists had believed that atoms were elementary particles. However, the discovery of the electron (J.J. Thompson), proton (Rutherford), and neutron (Chadwick), together with Rutherford’s evidence for a heavy, positively charged nucleus at the centre of the atom suggested the atom was not an elementary particle after all.
Brian Cox explains in this video clip…
To go further, we have to introduce some particle physics vocabulary.
These new elementary particles are part of our Standard Model of how the building blocks of the universe interact with one another. The particles that form “matter” are called fermions, after Enrico Fermi (Fermi has an incredibly long list of things named after him). The fermions are divided into two groups; quarks and leptons, as shown in the diagram below.
The Standard Model of Particle Physics. image: The University of Tokyo