Atomic stability

[phillip1882]

i was thinking of posting this in the "final theory" thread but then thought better of it. i was wondering if oppisites attract and likes repel, what keeps protons together in the neucleus and electrons from crashing and sticking to the center of an atom? i've heard of the "strong and weak neuclear force", but i dont really know much about it. where does it emenate from? how does it interact? any good refrence material on this subject for a begginner?

[CraigD]

i was wondering if oppisites attract and likes repel, what keeps protons together in the neucleus and electrons from crashing and sticking to the center of an atom? i've heard of the "strong and weak neuclear force", but i dont really know much about it. where does it emenate from? how does it interact?

This question could be better answered – or, more accurately, I think, started to be explored – by a more recent and advanced student of quantum mechanics than me, but I’ll make a pass at an explanation, in terms of my limited limited understanding of the Standard Model.

 

As Phillip mentions, there is a force known as the strong force or more precisely, the strong interaction. This is what keeps the three quarks of which a proton (2 ups and 1 down quark) or a neutron (2 downs, and 1 up) together, so completely that individual “free” quarks are never experimentally observed. This same interaction also overcomes the electromagnetic interaction that forces protons apart, allowing them to be bound together with neutrons into atomic nuclei.

 

As with all of the fundamental interactions described by the Standard Model (it describes 3 of the 4, The electromagnetic, the strong, and the weak, but not gravity), the strong interaction is “carried” by a particle. For the strong interaction, this particle is the gluon (for the electromagnetic, it’s the photon).

 

In the same way that quarks have electric charge (typically called just charge) that allows them to interact, in protons and with electrons, via photons, they have a kind of charge know as color charge that allows them to interact with one another via gluons. Unlike electric charge, which has 2 “kinds” - positive and negative - color charge has three – red, blue, and green. Instead of electromagnatism’s “likes repel, unlikes attract” rule, the rules governing color charge, know as quantum chromodynamics (QCD for short), has a “you must have one of each color” (a state known as “colorless”, or, less commonly, “white”) rule.

 

There’s much, much more to QCD than this, and in simplifying, it, I’ve made some inaccurate analogies. Also, as I confessed when I started, I don’t have genuine competence in the formalism of QCD and the Standard Model. Hopefully, though, these explanations can serve as a start to acquiring an introductory grasp of the subject.

any good refrence material on this subject for a begginner?

Yes, a lot. The wikipedia article linked to by the preceding, and the references linked from them are, IMHO, a good place to start. There are some “classics” on the subject, such as Feynman’s Lectures on Physics, and their though most people in my experience need to study more introductory textbooks, or at least have them on hand, before tacking even the “six easy pieces” and “six not so easy pieces” abbreviated compilations of these lectures. I’m sure others can offer many other recommendations.