What laws (formulas) govern the fundamental forces of nature?
For example, gravity is governed by the inverse-square law.
I am thinking about how particles attract each other, but also repel. All matter attracts via gravity, but also attract and repel each other due to the electromagnetic force, also governed via the inverse-square law, and then there's the strong and weak force.
I understand the idea that two hydrogen atoms repel, but when pushed together hard enough will attract and form helium and release energy. So this "upwards slope" of repulsion which is eventually "snaps" into attraction, like trying to roll a ball up a smooth hill with a hole in the center of it, is explained, likely, by varying forces governed by various laws. Can you help me understand it, on the level of particles?
Where I am stuck is thinking about two particles, each being attracted and repelled by two different forces each governed by the inverse-square law. This doesn't explain the "snapping" together of atoms. Do I need different math in my forces, or is it ultimately explained by more than just two particles?
Here is a diagram of what I mean, describing H + H -> H2:
Image source and article: http://employees.csbsju.edu/hjakubowski/classes/ch111/olsg-ch111/equilibkinetics/equilbkin.htm
Please feel free to reword my question if you understand what I am asking but am not making myself clear.
Best Answer
Not really an answer, but rather some organized comments.
First, you may become disappointed but the trully fundamental laws, as we know them today, are not written in terms of force laws. Even though the concept of force is still present in Physics, it is not used in the way it was before and which seems to be the way you are thinking about them.
Force is nowadays synonymous of interaction and one does not seek for force laws to be used in the equation \begin{equation}\vec{F}=\frac{d\vec{p}}{dt},\end{equation} from where one would, ultimately obtain $\vec{r}(t)$.
The above equation summarizes classical mechanics (CM) in its Newtonian "version" (or formulation). Even classical mechanics can be done without explicitly writing a vector equation as this one.
It was the analytic formulation(s) of CM that people took as the framework for doing advances in mechanics. They are all equivalent when it comes to the classical scenario and one uses one or another formulation for several reasons. Nevertheless, in the analytic formulations of CM, instead of using forces, as the quantities encoding the interaction, one uses potentials and the equations of motion are no longer obtained from Newton's second law (at least not explicitly as in the equation above) but from a more powerful principle, which is Hamilton's principle.
Now, even though in CM one may use any formulation according to one's needs, when it comes to relativistic classical mechanics and (relativistic) quantum mechanics, it is no longer a matter of choice. There are several reasons for why this is so. A very simple one, is that will won't be able to find a force four-vector to plug in the relativistic equivalent of Newton's second law (as it is written above) other than the Lorentz force. Also, in quantum mechanics (QM), Newton's second law holds only as an average (or expectation value).
This is why, even though one still speaks about forces, it is not in the same sense as before and we don't have other kinds of inverse-distance laws (or any other kind of vetor force laws) for the other fundamental interactions. Even the so-called potentials are not quite the same animals as in CM.
About What laws govern the fundamental forces of nature?, have a look at here.
Even the problems we try to solve with more fundamental physics are not quite the same as in CM. It is more about cross sections and decay rates than about describing the motion of individual particles (though that can be done to some extent).
I believe the particular phenomenon you are interested in is nuclear fusion. It is ultimately described in terms of electromagnetic and strong interactions and, even though in practice people may describe it in terms of more effective nuclear forces, it is still all done in the framework of relativistic quantum mechanics / quantum field theory and you won't find force laws.
To summarize: there are no force laws aside the ones of classical physics (Newton's gravitation law, Coulomb's electrostatic force and Lorentz force and some others).
I hope my comments help you.