While "visual indication" could mean just about anything, there are at least "indications" that there are "dimensions lower than us". By putting two semiconductors (that fulfill certain conditions that I don't want to get into right now) together, you can actually create a two-dimensional electron-gas (Wikilink). Naturally, they are technically three-dimensional, but as long as their energy is lower than a certain tresholdvalue (which you can easily control), they only have two directions to move in, and thus behave like a two-dimensional electron-gas.
If you do the math for such a gas (i.e. assume that there are only two dimensions), you'll find that it explains the behaviour of it.


Maybe not directly related to the discussion, but hey, maybe you're interested.