Ball Computers

I happened to be at Logan airport last week and while waiting for a flight to arrive I noticed the large "ball" structure/machine by George Rhoades. It looks very similar to these pictures but is titled "Kinetic Frugality". It's a structure of various sized balls that roll through tracks and strike chimes and bells as they roll along. Electric motors lift the balls back up to their starting points when they finish and the whole process restarts. Oddly I don't find that at George Rhoades own web page.

Anyway, it was "stuck". A large ball had rolled into a position where it was supposed to continue down a side track to a trampoline, but instead had come to a dead stop. I suppose eventually vibration from some passing truck or minor earthquake tremor (yeah, we get teeny earthquakes in New England) will shake it loose and let it continue along. While musing about that, I was also thinking about how disappointing this machine really is.

Disappointing? Oh, sure: watching the balls roll through their paths might hold your interest for a minute or two, but that's about it. You can admire the difficulty of construction, but at the end of the day it's a simple and very boring machine. It struck me that it would certainly be possible to do much more: it would be easy enough to build NAND and other logic gates with rolling balls, and as any first year computer science student knows, that's all you need to build a digital computer. With a bit of effort, you could design something that demonstrated simple computer technology in a very graphical way.

It seems that people have made more interesting ball machines: http://www.chilton.com/~jimw/ballclks.html talks about ball clocks, and there is someone who has done much more (at least in terms of diagrams) toward a ping pong ball computer. I'm imagining something more complicated, but the basic ideas are there.

Of course there were attempts to "compute" before electricity - Babbage's Analytical Engine being the usual example. That's certainly interesting, and people have build models, but I think a well designed "ball computer" could be a lot more fun to watch.

I'd be surprised if someone hasn't built something like this, but I came up dry on Google.. if you know of anything similar, please leave a note.