The All Forces Nullification Point is a point between the Tri-Galaxies where the fundamental interactions are negated. Theoretically, anything that passes through there would come apart as the forces holding it together disappear.
The Nullification Point was first visited by the crew of the Andromeda Ascendant and the remains of a High Guard fleet, hoping to rescue Tri-Jema from Collector Paroo, an agent of the Spirit of the Abyss. ("Answers Given to Questions Never Asked")
A year later, the Lambent Kith Nebula was planning on expanding the All Forces Nullification Point to encompass Known Space, hoping to destroy all life in the universe and the Abyss along with it. It is later revealed that this plan is in fact crafted by the Abyss who infiltrated and gained total control over the Nebula.