Surely you’re joking, Mr. Aaronson. I can (just barely) believe the musical instrument claim, but a computational device???
Actually, both claims are true, hard as it is to believe. For the musical instrument, watch this short video and you’ll see how it’s done…
What are all those water glasses doing there?
Ah, if you watched the video, you saw that it’s just your traditional glass harmonica, carefully re-created with a train calibrated to move at the right speed. Pretty cool, isn’t it?
OK, but a computational device seems more far-fetched. However, just take a look at Scott Aaronson’s article, and don’t get intimidated by the graph theory. If you do want to follow the mathematics, involving both graph theory and computational complexity theory, be sure to read the comments as well as the article itself! Unfortunately it’s not Turing-complete, but it’s still even cooler than the musical instrument.