I extract the below text snippet from our text book:

Strong interaction is charge independent.The time interval of such a strong interaction is about $10^{-23} sec$ and it's range is approximately $10^{-15} m$.

I don't understand what is meant by the time interval of a force?

  • $\begingroup$ seems to me that $\frac{10^{-15} \text{m}}{10^{-23} \text{s}} = 10^{8} \frac{\text{m}}{\text{s}} \approx c$ means that, like both EM and gravity, the Strong interaction propagates at the same speed $c$. $c$ is not merely the "speed of light" or the "speed of EM" it is more fundamental than that. as seen by a third observer equidistant from points A and B, if a cause at A results in an effect at B, the time interval between cause and effect is the distance between A and B divided by the same $c$. $\endgroup$ – robert bristow-johnson Nov 8 '14 at 16:04

The time $10^{-23}$ seconds is about the time needed for light to cross a distance of $10^{-15}$ metres, so you could interpret it as a timescale in this sense. However I'm not sure that the time interval of such a strong interaction is a terribly useful concept.

The nearest I can think of to a useful definition of time interval of such a strong interaction would be to look at the energy width of resonance peaks in measurements made at a collider, then relate this to the lifetime of the particle using the uncertainty principle.


This time is a time of a nuclear reaction. There are nuclear reactions with their characteristic times - how fast nucleons are rearranged during reactions, something like that.

  • $\begingroup$ would you give me a more detailed answer? $\endgroup$ – RogUE Nov 8 '14 at 15:02
  • 1
    $\begingroup$ @RogUE: Yes, I could give some details, but I do not want to. Please read more about nuclear reactions. $\endgroup$ – Vladimir Kalitvianski Nov 8 '14 at 15:29

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