Neutrino

From SGCommand

Neutrinos are particles that pass through any matter easily, no matter how dense. The Giant Aliens were able to create an environment where neutrinos were slowed down. (SG1: "Crystal Skull")

Asgard technology is dependent on neutrinos, from neutronium. The Asgard have built neutrino generators which put out 1 billion kilojoules of energy per second. (SG1: "Nemesis")