Alternate Reality
(split 2233)
Kirk in gravitational slipstream

Kirk and Krall caught in the gravitational slipstream of Yorktown

A gravitational slipstream was a "current" of force resulting from a balanced interaction of multiple artificial gravity fields. Such a slipstream was present at the central nexus of the Federation Starbase Yorktown.

In 2263, Captain James T. Kirk pursued Krall to the central nexus of Yorktown where Krall attempted to unleash the super weapon Abronath on the base's inhabitants. Struggling within the starbase's life support hub, the two men were caught in the gravitational slipstream of Yorktown, causing them to fly around the exterior of Yorktown Headquarters. Krall was able to observe the path of the slipstream via the movement of broken glass within it, and use the slipstream to return himself to the hub. (Star Trek Beyond)