Physics › Section W · Particle physics and frontiers › Topic W.1
Exchange particles and the four basic forces
Every push and pull in nature, from a falling apple to a glowing star, comes down to just four basic forces. Quantum physics explains each one as a stream of particles traded between the objects that feel it, and that picture even predicts how far each force can reach.
In this topic
- How does a force cross empty space?
- Exchange particles
- Borrowing energy: why range depends on mass
- Worked example: Yukawa's pion estimate
- A false lead: the muon
- The four basic forces
- Worked example: gravity against electricity
- Feynman diagrams and QED
- Mass, range and the carriers
- Common mistakes to avoid
- Key takeaways
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