From Stargate Wiki
- "What you're seeing is the accretion disk, it's matter trapped inside the gravity well. You can't see the black hole itself."
- — Rodney McKay
A black hole is a region of spacetime from which nothing, not even light, can escape. Matter commonly spirals into the black hole and creates an accretion disk, the only part of the phenomena that can be seen. Black holes spawn intense gravitational distortions and create unrelative time dilation effects. (SG1: "Singularity", "A Matter of Time", "New Order, Part 1")
P3W-451 was ripped apart by a black hole and killed SG-10, Stargate Command dialed into the planet and the black holes gravitational force created a lensing effect which formed an expanding time dilation field. The Asgard turned Hala's sun into a black hole and destroy the Replicators. The Ori used black holes to power their Supergates by collapsing planets. The planet Novus was ripped apart by the tidal forces created by a rogue black hole passing through the system. (SG1: "A Matter of Time", "New Order, Part 1", "Beachhead", "Camelot", "The Pegasus Project", SGU: "Epilogue")