We're at the phase where we know the world is quantum, but we also simply don't have the ability to bridge that set of observable phenomena to what we know about macroscopic things. That's what makes this exercise "silly".
We are not trying to prove who is right and who is wrong
Regardless of whatever the mainstream agreement in physics might be regarding a preferred model for reality, everyone experiences reality directly, without any need for science or math. And they can express those experiences and ideas in their own way
If you don’t agree with someone else’s ideas, please just explain why politely, and also maybe even try to understand their point of view. What would things look like if they were actually right? How might theirs be a good idea?
Thank you
"If you want to understand the transition between a fundamental theory and its effective description in some limiting regime, you need to be able to describe a system in the limiting regime using the fundamental theory"
Like, that's well and good, but in general we just can't do that without hand-waving, period. This is true all over the place (biology/physics, psychology/neuroscience/physics). It's sort of true, but not in a useful way.
> in general we just can't [describe a system in the limiting regime using the fundamental theory] without hand-waving, period...It's sort of true, but not in a useful way.
And I am saying that it in fact can be done, and has been done, in physics and math in a very non-hand-waving way. One can show rigorously when a certain abstractions is accurate.
It also illustrates the actual point pretty well - when you have a good set of differential equations that describe observed phenomena, that higher level of abstraction gives MORE insight into the processes at play, even when we know that it emerges from something more fundamental. Only when that model is a poor approximation do we need to appeal to the more fundamental regime (or when that fundamental regime is what we're studying).
Like, this comment of your is a great example of the sort of confusion that arises when you don't understand the non-relativistic limit:
> Lol, so you've got a working theory to bridge the quantum and classical worlds? That is, you've figured out how to make general relativity and quantum mechanics emerge from a more fundamental theory?