I don't get it...<p>It's this just a variant on the shortest path problem. Even a bad solution is going to look similar to a real rail network. There are plenty of good, easy algorithms to solve this, much faster than waiting a day for slime to grow.<p>Confused as to how this got in Science &#38; Wired. What am I missing (I didn't read the Science report, so maybe there's something there?)