Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Gravity and electromagnetism are inverse-square laws. This makes geometric sense -- if you build a spherical shell around a lamp then a shell with twice the radius has four times the surface area and hence a quarter of the intensity per unit area.

The strong interaction has a nontrivial distance-strength relation with an exponential term. Is there an intuitive geometrical explanation for this?

share|cite|improve this question
up vote 8 down vote accepted

I don't know of a geometrical explanation, but there is an explanation within quantum mechanics. In gauge theories forces are "carried" by vector bosons. For example, the electromagnetic force is carried by the photon, and the nuclear force (related to the strong force) is carried by the $\pi$ meson. The lifetime of the photon is infinite, so the outgoing flux of photons decreases by the inverse square of distance. The $\pi$ meson has a finite lifetime, so the outgoing flux of vector bosons falls off due to both the inverse square geometrical effect, and the declining flux due to the meson's lifetime.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.