I don't like the word "model" but creating models that describe whatever happens in the world basically describes my interest. I like to rephrase it saying, "creating mathematical structures that can properly describe stuffs that happen in nature". One example that I find intriguing is symmetries and degeneracies. The nucleus of an atom has a distance-only dependent way of attracting electrons. So the direction of an electron might doesn't quite matter - the only thing that matters is how far the electron is from the nucleaus, not whether it is up or down.
If we do some physics, which means solve the Schrodinger's Equation, we can find the energy of such electrons. We find that for several possible angles and directions, the electron has the same energy. This makes sense, because nucleus originally didn't have any direction dependents while attracting the electron.
In the language of physics, we like to call several directions of possible positioning of the electrons having the same energy as ``degeneracy". Electrons could be up, and still have the same energy while it was down beneath the nucleus - we call it degeneracy. (I am being really rough with my language for sake of explanation, sorry Physicists!).
The fact that the electron doesn't depend on the direction relative to nucleus as we compute the energy can be shortened into saying ``rotational symmetry". Up, down, left, right, 60 degree angle, -30 degree angle - it's all the same. This is a symmetry.
But now, say, we intentionally BREAK the symmetry. How do we do it? Turn on the magnetic field pointing upwards. Then looking at the system from various angles no more gives us the same thing. Rotational Symmetry is broken. But so what? Laws of Physics gives us that breaking such symmetry would also break ``degeneracies". Remember our energies of electron didn't matter which ever angle it had with the nucleus? Now we don't have that anymore, various angle have different energy - thanks to the broken symmetry caused by magnetic field pointing at a specific direction.
Why do I write this? - you may ask. Well every year
around the Physics Olympiad season I get this question
thrown at me from all possible directions.
And recently there's been a drama in Facebook related to
notable online teachers (like KhanAcademy, but significantly
worse quality (haha))
making serious mistakes while teaching. I shared my
opinion on that matter (remind me to add the link) and
I got asked again, "if such is the case, then how do I
properly understand Physics??"