Tear

"For I have looked into the future and one path is filled with amity and gold, and the other is fraught with the perils of a hostile and alien world."

- Saltonstall's speech, referring to a Tear

A Tear is a rip in dimensional time and space, revealing an alternate universe, which does not exist in the current world of Columbia. Every citizen of Columbia is able to see Tears, but Elizabeth is the only one able to create and interact with them. When tapping into these Tears, she is able to transport objects from the other side to the current world. However, she does so with the possibility of losing her concentration and causing the Tear to widen, producing unpredictable results.

When fighting the citizens of Columbia, Booker may encounter multiple Tears ranging from a single turret, to a few members of either the Vox Populi or The Founders, to a completely separate Sky-Line. Elizabeth is then able to transport these to Columbia's world to either supply objects or mend an existing counterpart, yet this also forces a risk to herself when using her ability.

History
In 1890, quantum-physicist Rosalind Lutece discovered the mechanics of suspending an atom indefinitely, coining it the Lutece Field. Father Zachary Comstock was inspired by his "vision" of the archangel Columbia commanding him to build a city of perfection in the name of God. Utilizing Lutece's mechanism, he set out to build the City of Columbia for his Project Icarus.

The US Government, after Comstock demonstrated what could be done, saw Columbia as an opportunity to spread the ideals of American society and success. They drafted Rosalind and her technology to make the floating city a reality.

By 1893, when Columbia finished construction, Rosalind discovered that an atom she was observing in her Lutece Field was being observed from an alternate universe. In that dimension was an alternate reality twin brother, Robert. They managed to communicate, through the atom being observed, by turning the Lutece Field on and off as Morse Code. The two managed to design a device capable of reaching other dimensions in the fabric of space and time and opening portals between them. These opened portals, or windows, to other dimensions are what were to be called Tears.

After creating the device, Zachary Comstock utilized the machine to maintain his status as a religious leader and prophet of the city. By using the device, he could see every possible future and outcome of Columbia and its people. However, exposure to the device caused Comstock's physical form to dissipate and blur, causing him to age rapidly. Despite being nineteen years old, Comstock had the physical attributes and appearance of a middle-aged man. Comstock soon discovered he had became sterile, and saw in a Tear Columbia would fall without his having a proper heir.

Rosalind proposed to Comstock they simply travel to a dimension in which an alternate healthy version of himself had conceive a child. Robert, revealed that Comstock in his universe remained Booker DeWitt, and fit, by not taking the life-changing baptism Comstock had. Comstock entered that universe with Robert and using him as an agent, offering to erase DeWitt's debts in exchange for his newborn daughter, Anna. DeWitt obliged but regretted his decision and went after them to get his daughter back. DeWitt found Comstock, Anna, and Robert about to enter the Tear and a struggled ensued. Comstock gained the upper hand and pulled Anna through, with the Tear closing on Anna's finger and severing it.

Robert and Anna were then brought through to Comstock and Rosalind's universe and Anna was renamed Elizabeth, becoming Comstock's heir. After bringing Elizabeth through, it was realized she had the ability to open Tears to other dimensions just as the machine had done. Because Elizabeth's body was separate in two realities at once, her physical form was spread out across the dimensional space. With Elizabeth's power and the machine's usage, the overall fabric of space and time became shredded. All around Columbia, Tear anomalies began to appear - connections to other realities. Citizens of Columbia could see through these Tears, and some used them to plagiarize works and inventions thus seen. This knowledge greatly furthered the progress of Columbia's technologies and their resulting wonders.

BioShock Infinite
At several points in the game, Elizabeth and Booker choose, for various reasons, to step through Tears, rather than bring the contents of a Tear to them. These Tears take them into alternate universes in which critical events occurred differently. Elizabeth has limited control over what kind of world these Tears lead to (she always thought of them as a form of wish fulfillment), but is unable to open a Tear leading back to a previous universe, making Tear travel a one-way journey. These Tears are occasionally unstable, leaving people who were nearby in either universe in a state of flux, which is especially traumatic if they are dead in the previous reality.

Rosalind Lutece devised a way of making and opening Tears through technological means, and opened one to bring her "brother" (her alternate self) Robert to her world. This was later used for a dimensional round trip for Robert and Comstock. During an attempt on their lives, Rosalind and Robert Lutece were scattered across the multiverse, and became able to create and open Tears without using their device. The Tear experience (at least the first trip) can be traumatic for the one crossing over and can cause amnesia, and result in new memories being formed from old ones. For Comstock, his prolonged exposure to the Lutece device may have granted him immunity to the trauma of crossing to other worlds, but at the cost of his fertility, health and sanity. The Boys of Silence have a limited use of Tears, and can use them to phase minions in and out of space-time to fight intruders.

Bioshock Infinite: Burial at Sea - Episode 1
Tears return to Rapture with almost the same mechanics, save for several new functions. Due to the fact that in an alternate universe, Jeremiah Fink used the tears to plagiarize Rapture's technology, tears that opened up to the Columbia timeline began appearing in Rapture by the mid-1950s. This caught the attention of biologist Yi Suchong, who was initially shocked when he saw Fink plagiarizing his own work. In a form of payback, Suchong stole Fink's idea for vigors and marketed them to Fontaine as "drinkable plasmids". Some of these plasmids were stored at Fontaine's department store, including Shock Jockey and Old Man Winter. It is likely that most of them were never manufactured to full extent (some of them were planned to be released by 1959, when the civil war broke out).

Suchong also managed to gain glimpses of Columbia, and hypothesized that the source of the "phenomena" was a strange young woman who appeared and disappeared from the tears. The tears could bring objects from Columbia into Rapture, such as freight hooks, weapons, turrets, and even motorized patriots. The tears also opened up to other time periods, possibly outside of both Rapture and Columbia--samurai from Feudal Japan could be brought into 1950s Rapture.

Types of Tears
In battles, the player will be presented with choices of what type of Tear Elizabeth should open. Once one of them is activated, the others will become temporarily unavailable. Some Tears appear individually and are only limited by Elizabeth's inability to open Tears for a set period of time.

Supplies
Opening a Tear of this type will bring in items that can be used as supplies or even a vending machine.

Salts
This variation will bring forth a barrel full of Salts to refill the player's  Vigor bar.

Medical Kits
This variation will bring forth a crate full of medical supplies or a broken Medical Kit vending machine to fill the player's health to full.

Cover
Opening a Tear of this type will bring an object primarily used as cover by the player. For example, Elizabeth can bring a Columbia Freight car onto a Sky-Line, which can be both used as cover and as a blunt weapon.

Freight Hook
These tears will summon a Freight Hook, which Booker can latch onto with his Sky-Hook.

Weapons
Opening a Tear of this type will bring a Weapons Barrel, or munitions to the player. The type of munitions provided varies. These Tears, coupled with destroying a Motorized Patriot, are the only ways to get ammunition for the Pepper-Mill.

Rocket Turret
This variation can be used to bring a stationary, heavy turret into the player's world for use against large enemy weaponry, such as Security Zeppelins.

Automated Turret
This variation will bring in a friendly automated turret, that does not require possession to fight for the player.

Motorized Patriot
This variation summons a friendly Motorized Patriot to fight for the player until its destruction, or at least until Elizabeth is ordered to open another Tear.

Mosquito
This variation will bring in a friendly flying turret, known as a mosquito. Like the other machines, it does not need possession.

Environmental Manipulators
Some Tears bring environmental hazards into the environment, allowing Booker to make use of certain Vigors to use them to great effect.

Oil Slick
Brings in a puddle of flammable oil into the environment, which can be ignited with Devil's Kiss.

Water
Brings in a pool of water from a busted fire hydrant. Electrifying it with Shock Jockey will cause it to electrify enemies in contact with the pool to be shocked for massive damage.

Tesla Coil
Warps in a powerful Tesla Coil, which will shock any enemies nearby. Any enemies under the effects of Undertow will be dealt extra damage.

Decoy
This Tear will bring in a stationary version of Booker that distracts enemies from the player's location while they attempt to attack it.

Food
In Shantytown, a Tear will bring in a supply of food to draw away people banging away on a vending machine, allowing the player to scoop up some Silver Eagles without creating a conflict.

Samurai

Only appears in DLC, a samurai is a helpful ally and it functions a same as Thuggish Splicers.

Trivia

 * According to an article from Gamasutra, the massive Tear that opens after Elizabeth's horse revival attempt was originally going to open to a primeval forest, not the 1980s. Ken Levine felt that world didn't have much of an impact to sell the concept for the Tear, so it was substituted with the 1980s world which reused building models from a canceled Irrational Games project.
 * In the factory tailor shop next to the Good Time Club, there is a glowing red "time tear" that neither Booker or Elizabeth could explain. The song coming the tear was Fortunate Son by Creedence Clearwater Revival, a song popular during the Vietnam War.
 * There is another "Time Tear" that is open in the late Albert Fink's studio, playing the song Girls Just Want To Have Fun by Cyndi Lauper. Albert had plagiarized the song and turned it into a steam organ ditty, which the player can listen to in Battleship Bay.
 * Boys of Silence are the only people besides Elizabeth, the Siren and the Lutece Twins capable of manipulating Tears, and it is implied they were granted their abilities through painful and mind-warping experimentation.
 * When Elizabeth opens the Tear to Paris (from the painting of the Eiffel Tower), in the cutscene used for the demo/trailer of the game the advertisement for the film shown in the cinema reads "Revenge of the Jedi", while the final version of the game reads the more appropriate "La Revanche du Jedi". Revenge of the Jedi was actually the working title of Return of the Jedi during its production.
 * Tears in Burial at Sea can bring objects from the Columbia timeline into Rapture, such as freight hooks, turrets, guns, and a Motorized Patriot.