User blog comment:Slopijoe/Battlefield 3 wins at the BAFTA's/@comment-1889554-20120318004339/@comment-3020230-20120320084107

It's a radioactive atom that may or may not decay. If it decays, there's a particle sensor that breaks a vial of poison that kills the cat. It's a method of visualising quantum entanglement. It also helps with understanding wave-particle duality.

Physics lecture over.