# What is keeping the protons and neutrons in the nucleus? Why aren't they flying into outer space?

They are constrained by the so-called $\text{strong nuclear force} \ldots . .$
The $\text{strong nuclear force}$ operates at impossibly short internuclear distances, i.e. ${10}^{-} 15 \cdot m$, and operates between protons (the charged) nuclear particles, and neutrons. At this range the force is two orders of magnitude greater than the electrostatic force that would tend to pull the nucleus apart because of electrostatic repulsion.