A real Turing machine

I saw this video and tweeted about it, but it’s so cool that I think it needs a blog post.

It’s a real live, operational, Turing machine (sans infinite tape, of course).

So, what’s a Turing machine?  It is a theoretical (until now) device that is capable of scanning, reading, and writing binary numbers onto a “tape” of cells (think of it as a binary array of infinite size).  Alan Turing (naturally) first described such a machine in order to provide a foundational representation of machine computing. It’s not practical, but it’s a good place to start.

Okay, it seems kinda silly, what’s the point?  The point is, well…there are a lot of points.  However, one of the most interesting things about the Turing machine is that a clear definition for “computer” can be written in terms of a Turing machine.  Formally, the Church-Turing thesis states that everything computable can be computed by some Turing machine. This can be taken one step farther: any machine that can simulate a Turing machine, is a computer. So, my laptop is a computer, my Xbox is a computer, and my calculator is a computer. But even an abacus is a computer, and even a bunch of rocks can be a computer!

Anyway, I tend to get excited about nerdy stuff like this, and I thought it was very cool that someone took down the nebulous mind’s eye view of a Turing machine and built it out with servos and a long film strip. It got me thinking about those long assignments writing out state machine diagrams and simulating Turing machine outputs on paper.