Concentrations of matter and energy warp the very fabric of space-time. If the densities and concentrations become too severe, the warp becomes almost infinite. Like water curling and swirling around a bath-tub drain, nearby space-time is accelerated into the vortex, eventually disappearing from view.
This little-understood phenomenon is known as a Black Hole. Energy and matter bleed away, departing our universe forever, while leaving only the imprint of their gravity. Likewise, a Black Hole may serve as a door from one universe to another—we simply don’t know.
(From Dr. Rodger Swift’s Abandoned Lab Journal.)