The fact that the nucleus is lighter than its constituents, seems rather strange. How can the whole have a smaller mass than its components? To get some intuition about how this is possible, one can look at a simpler more familiar system exhibiting the same phenomena; the hydrogen atom. It turns out that the same is true here; the hydrogen atom is a little bit lighter than the sum of its constituents. This difference corresponds to the ionisation energy of hydrogen. This observation allows a simple explanation for how this is possible; the destructive interference between the electric fields of the proton and electron causes a reduction in the energy of the electric field and hence a reduction in the contribution to the mass of the system from the electric field energy. The same explanation can be extended to the nucleus, thus giving some intuition about how this mass reduction happens. In the process, the idea of classical particles being ball-like objects with localised properties, is challenged.

原子核比其成分轻，这一事实似乎很奇怪。整体如何比其组件具有更小的质量？为了对如何做到这一点有一个直观的认识，我们可以看看一个更简单，更熟悉的系统，该系统展现出相同的现象。氢原子。事实证明，这里也是如此。氢原子比其组成总和轻一点。该差异对应于氢的电离能。这个观察结果为如何做到这一点提供了简单的解释。质子和电子的电场之间的破坏性干涉导致电场能的减少，从而降低了电场能对系统质量的贡献。相同的解释可以扩展到原子核，因此，可以直观地了解这种质量减少的过程。在此过程中，经典粒子是具有局部特性的球形物体的想法受到了挑战。