“Imagine you have been in a dream for the past 20 years. The dream universe you live in is a perfect replica of the waking state universe explored by scientists for the past several centuries.”

This is where you go wrong, in the very first sentence. Of course, by assuming the dreamworld is a “perfect replica” of the waking world, there is no way we can tell them apart. But dream worlds are never a perfect replica. And they are created by our minds, which the real world isn’t (so that is your point?)

But usually we recognized we are dreaming, for example when we are able to fly, or walk through walls - things we can’t do in the real world. And when we wake up, we usually remember our dreams, and recognize we dream about things we have experienced in life, usually in a distorted way.

If your drift is that, since we can’t tell dream from reality in a dream, we might as well be in a dream when awake, what is the point of this experiment?