The White Hole is a singularity, and the paired opposite to Brittle Hollow's black hole, from which objects may exit from, but not return through. Objects that fall into Brittle Hollow's black hole disappear and exit from the White Hole. Being the opposite of the black hole, the White Hole's reverse gravity repels any attempts to land on its surface.
There is no atmosphere around the White Hole, and the surroundings are entirely zero-gravity - Objects exiting the White Hole quickly come to rest in a static location around the Hole.
Near the White Hole itself from the beginning of the loop is the White Hole Station, a Nomai-built satellite containing a warp tower, for the purposes of quickly warping back to Brittle Hollow safely should one accidentally fall into the black hole.
While objects falling into the black hole exit at the corresponding location on the White Hole, should the player fall into the black hole, they will always exit facing the White Hole Station, regardless of their entry vector.
Over the course of the loop, bombardment from Hollow's Lantern causes sections of Brittle Hollow's crust, as well as the Lantern's fireballs, to fall into the black hole, exiting through and coming to rest around the White Hole.
This includes fragments containing key structures on Brittle Hollow late into the loop, including the Tower of Quantum Knowledge and Brittle Hollow's Gravity Cannon. The Tower itself is initially inaccessible under Brittle Hollow's gravity, but can be freely traversed in zero-g after falling into the White Hole.
The Nomai Warp Cores are heavily implied to be derived from the Black Hole/White Hole pair, manufactured at the Black Hole Forge. Research held by the Nomai discovered that Black Hole/White Hole pairs exhibit a unique temporal property - objects falling into a Black Hole exit its White Hole slightly before falling in, with the effect becoming more pronounced the more energy put into the system.