# How does electron capture occur?

Electron capture is a kind of decay by which a nuclear transformation takes place. Below is an example of it.

$$_{29} ^{64} \text{Cu} + e^- \to\ {}_{28}^{64} \text{Ni} + {\nu}_e$$

Of course, with the nucleus being positively charged and electron being negatively charged, there is an attraction between them, but electrons generally don't fall into the nucleus. I am unable to understand exactly how is the nucleus able to capture electron; using which interaction or force? The uncertainty principle won't allow an electron in the nucleus, though it is being captured. Exactly how?

• Indeed, electrons in $s$ wave orbitals have a contact density at the nucleus. This is also responsible for NMR (nuclear magnetic resonance) shifts and other hyperfine effects. – Pieter May 7 '18 at 11:11