The SNF and whether particles "touch" Hi there guys. I'm intrigued when reading about the Strong Nuclear Force and how it becomes repulsive at 0.5fm as to whether protons and neutrons "touch" each other. As far as I am aware the diameter of a proton is approximately 1fm. I am unsure whether to treat the force as acting from the whole proton or its centre. If I choose it to act from the centre then this would imply that the two nucleons are strongly attracted when touching each other, since the centres would need to be 1fm apart; or does it act from the centre of just one so that the other proton is considered as being 0.5fm away and just touching is equilibrium. If I treat the force as acting from the whole proton this implies that the protons are constantly separated by 0.5fm. So do the nucleons touch and if they do are they in equilibrium or constantly being pulled towards each other? (All this possibly making the mistake of considering them as billiard ball type things of course). Thanks!