A breach, also called a portal or wormhole, is a hole or rift in the dimensional barrier, bridging any location to another.
- "We need to think of the breach as a door, and on Earth-2, there's another door. In between, we have a hallway, but the hallway's constantly shifting, twisting, collapsing upon itself."
"And the doors keep moving with it."
- —Jay Garrick and Barry Allen[src]
On Earth-1, under the guidance of Eobard Thawne, Barry Allen ran fast enough to hit the hydrogen particle with enough speed to create a wormhole that served as a portal to infinite times. But the explosion created a singularity, a black hole above Central City, which also created a breach. On Earth-2, seeing a blinding light in which the skies parted and showed him another world, Hunter Zolomon/Zoom came to Earth-1 to steal Barry's speed. While Team Flash was successful in closing the singularity, there was a side effect. Using electrophotography, Cisco Ramon and Martin Stein found 52 breaches scattered throughout the city.
Zoom appears out of a breach with Sand Demon. He asks Zoom where he is and what he has to do to get home, and Zoom simply tells that all he has to do, is kill the Flash. Barry tries to speed through the breach under S.T.A.R. Labs, but isn't fast enough, and later, Harry comes through the breach. Barry is set on stopping Zoom, so the team choreograph a fight between him and Doctor Light to lure Zoom into an ambush, but he doesn't fall for it and comes through it later and captures Linda to get Barry's attention.
Before going to Earth-2 to save Harry's daughter, Jesse, Barry closes fifty-one breaches, leaving only open, through which Barry, Cisco and Harry use to cross over to Earth-2. The breach behind them destabilizes, but Jay and Caitlin fix it, and Barry, Cisco, Harry and Jesse eventually come back through, and seal it, but Zoom manages to grab and kill Jay, who is actually his time remnant.
With encouragement from Barry, Cisco taps into the energies that binds the multiverse together, as is his power, and reopens a breach to Earth-2 so that Barry and Zoom can face-off. But, Zoom gets away after a mini fight with the Flash, and takes Wally hostage as a bargaining chip. Barry gives Zoom his speed for Wally's life, further enhancing Zoom's speed, far beyond what it was before and curing him.
As a way to subdue the Earth-2 metas, the team sends out a high-pitch frequency specific to that of the frequency that Earth-2 vibrates at, affecting people from Earth-2, even Zoom, so Zoom creates a breach with his own power and hops through it.
Cisco later created an interdimensional extrapolator that could automatically open a breach between Earth-38 and Earth-1, and also added the ability to communicate between the two Earths. Kara Danvers utilized this to return to her Earth.
A temporal gateway is a larger version of a breach that is more stable and works on the same physics as a breach. At its full potential it can open a large enough breach to allow a Waverider sized object to get through. Rebels on Earth-X built a machine to open one and help bring hope back to that darkened world. After a battle with an unidentified vigilante, Oliver seized the device and used it to travel to Earth-1 to conquer it and save Kara from her solar radiation poisoning. After being taken to Earth-X, Barry Allen, Sara Lance, Alex Danvers, Martin Stein, Jefferson Jackson, Oliver Queen, Leo Snart, and Ray Terrill used the gateway to get back to Earth-1. It is presumed that Winn Schott had it blown up despite Barry and Ray stopping Red Tornado doing that before they escaped.
Breaches can be combined with super massive trans-matter portals to allow massive transport of billions between universes. Lena Luthor and Alex Danvers worked together to construct one of these devices to allow the residents of Earth-38 to be evacuated to Earth-1 before the antimatter wave hit. Just under half the residents, 3 billion, were evacuated on alien ships through the breach before the universe was overwhelmed and destroyed.
Hunter Zolomon said to look at a breach as like a "door," with a "hallway" in between that's always shifting and twisting, and if you stabilize the door, you stabilize the hallway.
Experienced speedsters can travel through breaches if they're fast enough. The "God of Speed" Savitar is even able to utilize them so well that he can hop in and out of a location. Reverb could open a breach to any Earth he so pleased, and Vibe could use breaches to travel around the city, but under great strain until he became more proficient with his powers.
DC's Legends of Tomorrow
Freedom Fighters: The Ray
The Chronicles of Cisco
- It seems to take more concentration and skill to for Vibers to open breaches to the same Earth, as evidenced by Cisco when he had trouble opening a breach from S.T.A.R. Labs to the water front, whereas he can easily open up breaches to other Earths, and Zoom never once transported around Earth-1 by using breaches. Savitar, however, utilized breaches with such preciseness and swiftness that he was able to shift about and appear anywhere in the city instantly, although this was only while he was manifesting himself in the real world from his Speed Force prison, which made him able to rapidly switch terrain and distance without even having to move himself.