What is the science of tincture/green dragon or canna oil/butter.

What is the science/chemical process that occurs when making tincture/green dragon or canna oil or butter? I have had success with several methods including Master Wu's and just soaking the weed in alcohol and letting it sit in a dark place for a month. I have no true scientific credentials, but from an entry level Anatomy&Physiology class it would seem that just letting it soak is simple diffusion and Master Wu's is a form of active diffusion, the same with making butter or oil? I really don't know, does anybody else?

We seem to rely on this as a form of alchemy but my hope is if I understand the chemical reaction that is occurring then do more with the concept. Yes, I know thc will bond with alcohol or fats, but how is it happening? It seems to be more than trichromes being washed off the plant but I am not sure what is really happening, does anyone have the ability to explain it to a non scientist.

Its not the same means of transfer as with butter or oil, but the same result.
The ethanol in the liquor acts as a solvent, thus making a THC solution.