The Fundamental Building Blocks
The Standard Model of Particle Physics is the theory describing the fundamental particles and forces that make up the universe, with the exception of gravity.
Elementary Particles
An elementary particle is a particle whose substructure is unknown; thus, it is not known to be made of other particles. These are the most basic building blocks. They are divided into two main groups: quarks and leptons.
1. Quarks:
These particles experience the strong nuclear force and are the building blocks of protons and neutrons.
They come in six 'flavors': Up, Down, Charm, Strange, Top, Bottom.
They also have a property called 'color charge' (red, green, blue).
Quarks are never found in isolation; they are always bound together in groups.
2. Leptons:
These particles do not experience the strong nuclear force.
The most famous lepton is the electron.
The other five are the muon, the tau, and their corresponding neutrinos (electron neutrino, muon neutrino, tau neutrino).
Composite Particles (Hadrons)
These are particles made of quarks.
Baryons: Made of three quarks. Protons (up, up, down) and neutrons (up, down, down) are baryons.
Mesons: Made of one quark and one antiquark.
The Four Fundamental Forces
All interactions in the universe are governed by four fundamental forces. In the Standard Model, each force is mediated by a force-carrier particle, a type of boson.
1.Strong Nuclear Force:
The strongest force, but with a very short range.
It binds quarks together to form protons and neutrons, and binds protons and neutrons together in the atomic nucleus.
Carrier Particle: Gluon.
2.Electromagnetic Force:
Acts on any particle with electric charge.
Infinite range, but weakens with distance.
Responsible for electricity, magnetism, and light.
Carrier Particle: Photon.
3.Weak Nuclear Force:
Responsible for certain types of radioactive decay (beta decay).
Very short range.
Carrier Particles: W and Z bosons.
4.Gravitational Force:
Acts on any particle with mass.
Weakest of the four forces, but has an infinite range.
It is not currently included in the Standard Model. Its hypothetical carrier particle is the graviton.