Fundamental Machinery of the Universe: Particle Physics

Introduction

• Kids ask difficult questions like “Why do things exist?”
• Standard Model of Particle Physics: Best description so far of fundamental universe
• Goal: Understanding what exists and how it behaves, setting the context for news on evidence beyond the standard model

Overview of Particle Physics

• It’s incomplete with unresolved mysteries
• Brief coverage in the map of physics and the map of quantum physics
• Fundamental particles summarized in a map

Fundamental Particles

Fermions and Bosons

• Fermions: Make up physical matter
  • Have spin of 1/2
• Bosons: Mediate interactions (force carriers)
  • Have spin of 1 or 0 (Higgs boson)
• Spin: Form of angular momentum in quantum mechanics
  • Particles have wave functions, spin defines behavior under rotation in 3D space
  • Spin conservation is a key rule in particle interactions

Quarks and Leptons

• Quarks:
  • Up/down quarks make protons and neutrons
  • Can’t exist alone, always bundled (e.g., pion)
  • Carry electric charge (2/3 or -1/3)
• Leptons: Include electrons, muons, taus, and neutrinos
  • Electrons: Chemical bonds, electricity, emit/receive photons
  • Muons and taus: Higher mass, unstable
  • Neutrinos: Very small mass, interact with weak force only

Conservation Laws and Interactions

Key Conservation Laws

• Spin, energy, linear momentum, electric charge
• Baryon number
• Color charge (specific to quarks; red, green, blue analogy)
• Lepton flavor (electroneus, muon-nus, tau-nus)

Field Interactions

• Electromagnetic Force: Interacts with particles carrying electric charge
• Strong Force: Interacts with quarks and gluons
• Weak Force: Interacts with all fermions, responsible for certain decays
• Higgs Field: Provides mass to particles

Notable Concepts

• Pauli Exclusion Principle: Fermions can’t share same quantum state
  • Critical for atom behavior and chemistry
• Composite Particles: He atoms as bosons
  • Result in phenomena like superfluidity and superconductivity

Quantum Numbers and Symmetries

Additional Quantum Numbers

• Baryon number
• Color charge: Quarks need to be color-neutral when combined
• Flavor of leptons: Each type of lepton has its own quantum number

Symmetries in Physics

• Parity Symmetry: Mirror image universe
• Charge Conjugation Symmetry: Switching particles to antiparticles
• CP Violation: When both parities and charges change but not conserved
• CPT Symmetry: Combination of charge parity and time reversal

Bosons and Forces

• Photons: Electromagnetic force carriers
• Gluons: Strong force carriers
• W and Z Bosons: Weak force carriers
• Higgs Boson: Mass-providing particle

Outstanding Questions and Future Research

• Unresolved Issues: Baryon asymmetry, dark matter, masses of neutrinos
• Mysteries: Magnetic monopoles, weak gravity, exact particle combinations
• Future: Bigger particle accelerators, underground detectors for dark matter

Supporting Resources

• Posters and educational materials available on the DFTBA store
• Sponsorship message about Brilliant.org for learning courses in physics and more.