The Floaty Dimension is actually displaced in time.Professor Quadwrangle is right about that dimension's mansion being upside-down... but it's only that way because the mansion is flipped upside-down after you activate the Uber-IDS.
Science Juice is IKE's waste.It would explain a lot, wouldn't it?
IKE is actually the game's villain and is responsible for the experiment going awry.That's why he gets upset when you take the dimension batteries from him: he doesn't want you to progress. This continues right up to the end of the game, when he gives you the four batteries in rapid succession...right when it would be a very bad idea to use them. And why did he do it? So he could keep the secret of dimension-hopping all to himself, of course!
This man is not your uncle.He's actually Q. Or Discord. Then again, those two are probably the same person. He just conned you into thinking you were his nephew and that he got irrevcoably trapped in limbo because he wanted to make you go through the crazy house and mess with the dimensions. Because that's the kind of thing Q/Discord would do for kicks.