Questions about a neutron star

a reply to: Arbitrageur

Sometimes they do decay.

and the explanation for that is so convenient...

they sometimes decay because they sometimes hungry for energy, or better said they f.. the "rule" for staying at the lowest energy level...

they must be triggered by something, right ?

what is it ?

a reply to: KrzYma
In stable atoms they don't decay. In unstable or radioactive atoms they do and that gets into why unstable atoms are unstable, because of complex particle interactions in the nucleus:

Neutron Stability in Atomic Nuclei

The neutron lasts 15 minutes; but there are nuclei that survive for milliseconds, days, decades, millenia, even billions of years. These nuclei are what we call radioactive; they are the dangerous aftermath of radiation accidents or weapons, and the tools used in smoke detectors and in fighting cancer, among other applications.

There are a number of different ways that these nuclei can fall apart, but some of them decay by having a neutron convert to a proton inside a nucleus. (We know this because the charge of the nucleus increases, and an electron comes flying out, along with an anti-neutrino.) Others even decay by having a proton convert into a neutron! (We know this because the charge of the nucleus decreases, and a positron [an anti-electron] comes flying out). Figuring out how long a given type of nucleus will survive, and how it will decay, is very complicated nuclear physics — I won’t give you a course in that here (indeed I’m no expert).

Suffice it to say that negative interaction energy among particles, combined with the conservation of energy, can change the game in a big way, making impossible certain processes that are normally possible — and vice versa.