Charge, 2

Charge (physics), the susceptibility of a body to one of the fundamental forces

  • Color charge, a property of quarks and gluons, related to their strong interactions
  • Electric charge, a property which determines the electromagnetic interaction of subatomic particles
  • Magnetic charge, a property of theoretical magnetic monopoles

— Wikipedia on Charge

Symmetry and conservation

Conservation of momentum is a mathematical consequence of the homogeneity (shift symmetry) of space (position in space is the canonical conjugate quantity to momentum). That is, conservation of momentum is a consequence of the fact that the laws of physics do not depend on position; this is a special case of Noether’s theorem.

— Wikipedia on Momentum

Momentum is the Noether charge of translational invariance. As such, even fields as well as other things can have momentum, not just particles. However, in curved spacetime which isn’t asymptotically Minkowski, momentum isn’t defined at all.

2014.06.19 Thursday ACHK