|Books location||TV location|
The Slow Zone, the Ring Space or the Hub is the location on the other side of the Ring. It's a black, starless spherical space approximately one million kilometers across, with 1,373 individual wormholes. At the center of this space sits the Ring Station. The actual location of the slow zone in space, or whether it is connected to the universe, is unknown.
- Main article: Slow zone incident (Books)
The slow zone was named for its absolute speed limit of six hundred meters per second. Any object with non-zero invariant mass moving faster than this limit is locked down by an inertial dampening field and then begins to move towards the central Ring Station, forming a ring around it. Light still acts normally and adheres to the speed of light, but radiation made up of larger particles like alpha and beta radiation does not exist inside the slow zone.
After the flotilla succeeded in following The Investigator's advice and powered down their ships, the speed limit inside the slow zone was lifted and all rings that still had an active ring on the other side reactivated. Following this, the area became known as "the hub".
The retrofitted OPA ship Behemoth relocated permanently to the hub and became Medina Station. The slow zone is blockaded at the Sol Ring by the United Nations and the Martian Congressional Republic. Refugee Belters from Ganymede, however, break through the blockade, enter the slow zone, and rush out to the later-named Ilus system.
Communication from the Sol system to the Slow Zone and Medina Station is lost following the breakout of the Free Navy Conflict. This occurred with the help of the once OPA-backed Captain, Christina Samuels, who switched to the Free Navy and halted all traffic through the Slow Zone. Colony worlds also lost communication to the Slow Zone - except for the Laconia system, since they were allied with the Laconian Imperial Navy, which controlled it.
Six months after the Consolidated Fleet defeats the Free Navy in the Slow Zone, James Holden proposes what will become the Transport Union. It will be run by Belters and will manage the flow of ships in and out of the Slow Zone.
Images and video from Kelvin Paul Marchioro. 
- The "speed limit" is described as an active defense mechanism of the Ring Station in Abaddon's Gate, rather than a fundamental change in the constants of nature. "The speed limit grips the hull of the ships, but anything inside is unaffected." This effect is used as a key plot element throughout Abaddon's Gate. Bullets fired from weapons behave normally inside ships. However, when a Martian marine inside of the Ring Station attempts to launch a grenade, it "comes to a halt and drops to the ground centimeters from the barrel." When the speed limit comes into effect, crew and passengers are injured or killed due to the sudden deceleration of their ships' hulls.
- Initial readings also suggest that the background microwave radiation in the slow zone is older than the Big Bang.