Can one build a "mechanical" universal Turing machine? This question connects different disciplines so it's awkward to choose a SE site for it, but I'll go with this one because here (I hope) the shared culture will make information transfer easier.
So computers as we know them use electricity and I don't know what other invisible things that I don't understand. I was wondering, is this a matter of efficiency, or of necessity? Can one achieve universal computation with just &quot;moving parts&quot;? Perhaps &quot;Newtonian physics&quot; is some term for this, although I guess it includes gravity which isn't really what I mean. You know, just good old solid pieces of matter moving around.
To get some picture of what I mean, here is a &quot;LEGO Turing machine&quot;. I'm afraid that the big gray block on top uses electricity, but could one replace it with a &quot;mechanical&quot; thing, powered perhaps by rotating a piece? I have no idea how such things be designed, and the state transitions for a universal TM have to be fairly complicated, so I have no intuition for whether this is possible or not.
Sure. Electricity is unrelated to the model of computation.
The only thing you can't actually build is the infinite tape, for obvious reasons. In this sense, anything that can be built is essentially equivalent to a deterministic finite automaton.
Here's a Turing Machine made of wood:
https://www.youtube.com/watch?v=vo8izCKHiF0&amp;ab_channel=RichardRidel