23.1 The Four Fundamental Forces

The four fundamental forces govern all interactions in the universe. Gravity and electromagnetism have infinite range, while strong and weak nuclear forces act at subatomic scales. Each force has a unique strength and role in shaping the physical world.

Force-carrying particles called bosons mediate these interactions. Photons, gluons, and W/Z bosons transmit electromagnetic, strong, and weak forces respectively. Gravitons, though unconfirmed, are thought to carry gravity. Understanding these forces is crucial for explaining the universe's behavior.

The Four Fundamental Forces

Four fundamental forces

Top images from around the web for Four fundamental forces

• 

  GUTs: The Unification of Forces · Physics View original

  Is this image relevant?

• 

  The Four Basic Forces | Physics View original

  Is this image relevant?

• 

  GUTs: The Unification of Forces | Physics View original

  Is this image relevant?

• 

  GUTs: The Unification of Forces · Physics View original

  Is this image relevant?

• 

  The Four Basic Forces | Physics View original

  Is this image relevant?

1 of 3

Top images from around the web for Four fundamental forces

• 

  GUTs: The Unification of Forces · Physics View original

  Is this image relevant?

• 

  The Four Basic Forces | Physics View original

  Is this image relevant?

• 

  GUTs: The Unification of Forces | Physics View original

  Is this image relevant?

• 

  GUTs: The Unification of Forces · Physics View original

  Is this image relevant?

• 

  The Four Basic Forces | Physics View original

  Is this image relevant?

1 of 3

• Gravity attracts objects with mass has infinite range but is the weakest force (apple falling from a tree, planets orbiting the sun)
• Electromagnetism attracts or repels electrically charged particles has infinite range and is stronger than gravity (static electricity, magnets)
• Strong nuclear force attracts quarks holds protons and neutrons together in the nucleus is the strongest force but has a short range limited to the size of an atomic nucleus (binding protons and neutrons in the nucleus of an atom)
• Weak nuclear force causes radioactive decay and neutrino interactions has a short range like the strong force but is much weaker (beta decay, nuclear fusion in the sun)
• Each force has a characteristic coupling constant that determines its strength in interactions

Carrier particles in force transmission

• Bosons are force-carrying particles that mediate interactions between matter particles (fermions)
  • Photons mediate the electromagnetic force (light, radio waves)
  • Gluons mediate the strong nuclear force (binding quarks together)
  • W and Z bosons mediate the weak nuclear force (radioactive decay)
  • Gravitons (hypothetical) are thought to mediate the gravitational force (not yet observed)
• Virtual particle exchange transmits forces through the exchange of virtual bosons between interacting particles
  • Virtual particles briefly exist and mediate forces without satisfying the usual energy-momentum relationship $E^2 = p^2c^2 + m^2c^4$ (Heisenberg uncertainty principle allows virtual particles to borrow energy for a short time)

Theoretical frameworks for understanding forces

• Field theory describes forces as interactions between particles and their associated fields
• Gauge theory provides a mathematical framework for describing the symmetries of fundamental forces (electromagnetism, strong and weak nuclear forces)
• Quantum mechanics is essential for understanding the behavior of particles at the subatomic level, including their interactions through fundamental forces

Particle accelerators for subatomic research

• Particle accelerators like the Large Hadron Collider (LHC) enable scientists to study high-energy particle collisions
  1. Collisions produce new particles allowing researchers to investigate the properties and interactions of subatomic particles (discovery of the Higgs boson in 2012 confirmed the existence of the Higgs field which gives particles their mass)
  2. Precise measurements of particle properties help validate or refine theoretical models (testing predictions of the Standard Model which describes three of the four fundamental forces excluding gravity and classifies elementary particles)
• Accelerators explore physics beyond the Standard Model
  • Searching for evidence of supersymmetry extra dimensions and dark matter particles (could lead to a more comprehensive understanding of the fundamental forces and the unification of gravity with the other three forces)
  • Future discoveries may reveal new particles or interactions that expand our knowledge of the subatomic world (potential discovery of the graviton or evidence of a theory of everything)
  • Experiments aim to test grand unified theories that attempt to combine the electromagnetic, strong, and weak forces into a single framework