You can't look at the "real weather" though. You can only look at the outputs. That's the constraint. Good luck and have fun.
A human brain is a big pile of jellied meat spread. An LLM is a big pile of weights strung together by matrix math. Neither looks "intelligent". Neither is interpretable. The most reliable way we have to compare the two is by comparing the outputs.
You can't drill a hole in one of those and see something that makes you go "oh, it's this one, this one is the Real Intelligence, the other is fake". No easy out for you. You'll have to do it the hard way.
Even granting all of your unfounded assertions; "the output" of one is the rain you see outside, "the output" of the other is a series of notches on a hard drive (or the SSD equivalent, or something in RAM, etc.) that's then represented by pixels on a screen.
The difference between those two things (water and a computer) is plain, unless we want to depart into the territory of questioning whether that perception is accurate (after all, what "output" led us to believe that "jellied meat spread" can really "perceive" anything?), but then "the output" ceases to be any kind of meaningful measure at all.
there is no "real weather". the rain is the weather. the map is not the territory. these are very simple concepts, idk why we need to reevaluate them because we all of a sudden got really good at text synthesis
Everyone's a practical empiricist until our cherished science fiction worldview is called into question, then all of a sudden it's radical skepticism and "How can anyone really know anything, man?"
A human brain is a big pile of jellied meat spread. An LLM is a big pile of weights strung together by matrix math. Neither looks "intelligent". Neither is interpretable. The most reliable way we have to compare the two is by comparing the outputs.
You can't drill a hole in one of those and see something that makes you go "oh, it's this one, this one is the Real Intelligence, the other is fake". No easy out for you. You'll have to do it the hard way.