Overview

Particle Physics (High Energy Physics) is the quest for the ultimate building blocks of the universe. It smashes atoms together to see what’s inside.

Core Idea

The core idea is reductionism. If we understand the smallest things (fundamental particles) and the forces between them, we understand everything.

Formal Definition

The study of the fundamental constituents of matter and radiation, described by the Standard Model.

  • Fermions (Matter): Quarks (protons/neutrons) and Leptons (electrons).
  • Bosons (Forces): Gluons (Strong), W/Z (Weak), Photons (EM), Higgs (Mass).

Intuition

It’s cosmic Lego.

  • Quarks: Up and Down quarks stick together (using Gluons) to make Protons and Neutrons.
  • Electrons: Orbit the nucleus to make atoms.
  • Neutrinos: Ghostly particles that pass through Earth by the trillions.

Examples

  • Large Hadron Collider (LHC): A 27km ring in Switzerland that accelerates protons to near light speed to create new particles (like the Higgs Boson).
  • Antimatter: Every particle has an evil twin with opposite charge (Electron vs. Positron). When they meet, they annihilate into pure energy.

Common Misconceptions

  • Misconception: Atoms are the smallest things.
    • Correction: Atoms are made of protons/neutrons, which are made of quarks. Quarks (so far) seem to be point-like (no size).
  • Misconception: The “God Particle” (Higgs) proves God.
    • Correction: It’s just a nickname (originally “Goddamn Particle” because it was hard to find). It explains why things have mass.
  • Quantum Mechanics: The rules these particles follow.
  • Dark Matter: Mysterious stuff that makes up 85% of the universe’s mass but isn’t in the Standard Model.
  • String Theory: A proposed theory that particles are actually tiny vibrating strings.

Applications

  • Medicine: PET scans (Positron Emission Tomography) use antimatter. Proton therapy treats cancer.
  • World Wide Web: Invented at CERN by particle physicists to share data.

Criticism and Limitations

  • Cost: Accelerators cost billions.
  • Incompleteness: The Standard Model doesn’t explain Gravity, Dark Matter, or Dark Energy.

Further Reading

  • The Particle at the End of the Universe by Sean Carroll
  • Introduction to Elementary Particles by David Griffiths