Before you go out and spend hundreds of dollars on a fancy Lionel train set to circle your Christmas tree, here's a simple but remarkable science experiment that will save you a few bucks and blow Santa's mind when he stops by on the 24th.
The 'train' is actually just a AAA battery with a couple of stacks of small magnets attached to either end, and when placed inside the entrance of a tight coil of copper wire, they're pulled through the tube like magic. And if you connect the ends of the coil to create a single sealed loop, you've instantly got yourself a simple toy train that will presumably keep running until that battery dies.
The video doesn't really explain why this trick works, but most commenters believe it functions similar to a homopolar motor which is the same technology that powers the incredibly lethal rail guns the US military is developing. But this use of the science behind the technology is of course a whole lot safer. [YouTube via Neatorama]