In this clip from Genius by Stephen Hawking, the three volunteers look to discover if the laws of nature also apply to the tiniest structures in the subatomic world. By using balloons to act as electrons the volunteers can replicate how electrons behave. Balloons are light and naturally buoyant, similar to electrons; and the lighter an object is the harder it is to pin down. The volunteers find that the lightness of these balloons makes them hard to catch, there is no constant in how the balloons behave which is similar to electrons. On the smallest of scales, matter behaves in a very strange and indistinct way, and there is a fundamental limitation to the accuracy with which the position and velocity of a microscopic particle can be known. The idea that there is randomness at the core of the universe is known as Heisenberg's Uncertainty Principle.