Many universes-where?

a minor dialectical analysis

It is heard often: many worlds, multiverse. It is discussed often among the higher sciences. They tend to use the language which makes it sound like "many worlds" is a given. That they are already there.

Is this compatible with research for quantum? Quantum deals with the microworld, not large systems. If things arise from microsize then that indeed is where it should be focused. So, how does a large system appear? By what means are they postulated?

According mostly to what we so far assume about large, physical systems, they start out with small particles, not just pop into existence as a large system, by passing quantum development. The small stuff has to attract and then combine and sustain. From that process in general may more tangible stuff appear.

So is this being confirmed as pervading? Especially outside of our known cosmos? It could be some are jumping the gun thereby by positing "many worlds, multiverse" where there is not confirmed evidence of the quantum and the building process occurring. One may think them up to be, but they have to likely pass through the process of growing from the microworld first, before being posited, according to the presumably known orderliness. This is how the big stuff would appear. Has that been ascertained for the "many worlds or multiverse" or is it just the nature only of thoughts?

Note: the material herein is not necessarily a reflection of entropy of current societies.