Joshua Kronengold

I've spent some time thinking about how to build a classic Turing machine in clockwork, and I have to say that, as awesome as this is (and the ad is as awesome as the machine), I feel that using real electronics is cheating. At least, using real electronics to implement the state machine is cheating — I suppose a version where the state machine was made of LEGOs, and where the MindStorms controller was only used as, if you will, BIOS (to cover for not being a master watchmaker), would be okay.

As for making the state machine out of LEGOs... remember a state machine is just a labeled directed graph, easy enough to make as a kind of train track. The only trouble is, the machine has to be simultaneously moving along the state graph and the tape, which means it has to be carrying the whole state graph along with it. I had imagined the state graph as a groove carved into a wooden sphere (which would be adorably steampunk), but you could probably do it on a flat surface with LEGOs if you could figure out how to stop it from falling off.

However, for the win: "Infinite tape* *Subject to availability"