The dark matter is a substance of which little is known. In scientific terms, dark matter refers to matter undetectable through electromagnetic interactions, meaning that it can't reflect light and thus is invisible. In Futurama, it is used as a starship fuel, which Nibblonians excrete. It is the densest, and therefore heaviest, substance in the universe, with each ball that Nibbler produces weighing as much as 1000 suns. According to Professor Farnsworth, dark matter is so dense that "each pound of it weighs over ten thousand pounds."
During the third time he worked for Mom, Professor Farnsworth used a particle accelerator to smash some dark matter in an ill conceived attempt to create a more durable harpsichord wax. In the process, he created a non-local metaparticle crystal that empowered dark matter as a fuel and an Anti-Backwards Crystal, that if in six inches proximity to the fuel crystal, could render all dark matter useless. Mom took the first crystal to hold a dark matter enterprise over the universe. She even mined out the dark matter resources of Vergon 6, which was filled up with the Nibblonians stationed there. Upon realizing the "cute runts" could produce the fuel, she captured a ship full of them, except Nibbler. Her company force feeds the Nibblonians so they will mass produce dark matter.
Mom instigated a dark matter shortage to gain higher prices. However, as a result of Professor Farnsworth attempting to use the Anti-Backwards Crystal, all dark matter is rendered useless. Professor Farnsworth comes up with a temporary fuel "Nibbler power".