That's because arcs are kind of like semi-random searches through air for a place that will equalize the voltage. See, for example, slow-motion videos of lightning: https://www.youtube.com/watch?v=7kI1d7DMbco
The "Wilson" of the title is David Bruce Wilson (http://dbwilson.com), an accomplished mathematical probabilist, who may be familiar as a developer of perfect sampling ("Propp-Wilson") for Markov chain Monte Carlo computations.
> Initially, the algorithm can be frustratingly slow to watch
By "frustratingly slow", what are we talking about? It's been running for over an hour with no progress and my computer at work automatically reboots over the weekend. How long do I need to keep this tab open?
It depends on whether a the algorithm can generate a sufficiently large path (the white line) at first, since further development requires the purple path intersect that fixed path.
Finally finished. Question: I see I can inspect the canvas element and even edit the code. How do I run it with my edits (without pushing it to a server?)
Thanks for the easy-to-follow instructions. I could quickly come up with an updated, less-likely-to-bore version ( http://bl.ocks.org/mdengler/a36fac5f10098bb94846 ), and included a version of your instructions and link to your comment.
http://bl.ocks.org/mbostock