Here's a really cool, classic experiment that's always fun to see. When you place uranium inside a cloud chamber, you can see it decay and emit bits of radiation. It's like seeing little alpha particle torpedoes shooting out in every direction, leaving a trail behind.
You can actually do this type of experiment at home too by following these instructions. Below is a video showing nearly an hour's worth of footage.
This article originally appeared on Sploid, a Gizmodo blog of delicious brain candy