Esper

An esper (能力者) is an individual who uses scientifically based supernatural powers and emits AIM. The term usually refers to those enrolled in the Academy City Power Curriculum Program, who gained their powers artificially, but can also refer to natural espers, also known as Gemstones. It is also used to refer to magicians by those unaware of the magical nature of their abilities, and therefore treat them as esper-related.

In-universe, espers have only existed for a few decades up until this point.

Terminology
The original Japanese light novels used the term "Ability User", but before the licensing of Toaru Kagaku no Railgun, the majority of the English-speaking fandom substituted it with "esper". Because its use has become widespread, this wiki uses the term "esper".

A queer event related to this is Seven Seas' English translation of the first volume of A Certain Scientific Railgun, which opted to use "psychic", a term that has been used before by the fandom until "esper" became the standard. Because of this, the English fans that were accustomed to the use of "esper" lobbied for "psychic" to be changed, and Seven Seas acquiesced, even referencing the incident later.

The term "esper" does not automatically imply ESP, one of the two classifications of powers in Academy City, as it could also refer to an ability user that does not have extrasensory perception but instead influences objects in their surroundings, referred to as Psychokinesis. Abilities such as Pyrokinesis are considered esper powers despite the user not having extrasensory perception.

Principles
Academy City's espers have existed for over half a century in the world of Toaru, with the first modern esper being a girl nicknamed "the Beginning Child", who was trained by Academy City based on Meiji-era psychic 's data. The system used for the Beginning Child would become the foundation for the Power Curriculum Program to create espers.

Espers are described by Index as individuals with "talent"; this likely refers to Gemstones and each cannot use magic without injuring themselves. An esper is created after passing through the Power Curriculum Program, thanks to which the esper now possesses a Personal Reality, their capacity to substitute reality with their own which is the basis of their abilities, with no two people have the exact same one. In contrast to Magic's Idol Theory, their interference with and subsequent distortion of reality to create effects is an isolated phenomenon based on, their observations of the world based upon their Personal Reality affecting things on a micro quantum level to cause phenomena on a macro level. An opposite theory would be holism, where a large interference with the laws of the whole world is used to make effects on a smaller scale. Aside from the mental performance of calculations, no elaborative and preparatory rituals are required by an esper to produce effects related to their abilities, unlike in Magic.

Espers can only access one specific power; Misaka Mikoto, for example, can only control electromagnetic phenomena. Despite this, however, researchers have attempted to create espers with multiple powers, such as Dual-Skill and Multi-Skill espers. Moreover, esper abilities are compartmentalized into two categories: Active and Passive. Active abilities require conscious effort to use, while passive abilities require subconscious effort. Abilities can be classed as both active and passive, such as Accelerator's ability. Esper abilities are further grouped into two major categories, Psychokinesis (PK) and Extrasensory Perception (ESP), with PK having a higher precedence in the classification of esper powers than ESP, especially when an esper power sits on both sides of the boundary between ESP and PK.

Another aspect of espers is that every one of them, even Level 0s, subconsciously radiates an AIM Diffusion Field, minutes amount of their power in a way akin to body heat and weak enough that it can be felt by any of the human five senses and is only detectable through machines. Different powers means a different AIM Diffusion Field: a Pyrokinetic for example will emit AIM that will heat up their environment, a Telekinetic will emit pressure, and an Electromaster will emit a weak magnetic field. According to the Professor, AIM is not simply weak energy emanating from espers, but the unconscious interference against reality, and analyzing its composition and strength gives more insight into the Personal Reality of a given esper than a psychological profile. There does seem to be some direct connection between the AIM Diffusion Field and Personal Reality, if Takitsubo Rikou being able to affect the latter through the former is any indication.

Esper powers are controlled using complex calculations done mentally, so strongest espers are also Academy City's greatest honor students. Because esper abilities rely on mental calculations and concentration, if anything affects the esper mentally, be it pain, exhaustion, surprise, or confusion, they will not be able to perform the calculations needed and their powers won't work. The AIM Jammer takes advantage of this, essentially disturbing espers' concentration.

While the brain is an important component to esper power, it is not the only factor. The entire physical human body is also part of this system and controls the power, though the exact mechanism is not well understood. Produce tested and researched to find out where exactly in the body esper power resides, removing limbs, organs, and brain parts from subjects, but the power still remained, although its output decreased as the body grew smaller, leading the researchers to conclude esper power can only reside in a body containing something that could be called a soul. Likewise, it is shown that, as long as something is considered a part of the body by the esper, esper abilities can be used with it, no matter if that part is attached or detached, artificial or natural. Kuroyoru Umidori can use Bomber Lance through her detached cyborg arms, which she considers parts of her body; Kakine Teitoku can control his Dark Matter even if it's not directly touching his body by no longer distinguishing between his actual body and the parts fabricated from his power;  and Rensa operates by changing her biological structure to that of other espers so she can use their abilities. Coffins also operate on this principle, tricking the brains of dead espers into thinking bigger mechanical bodies are their own, which in return make the power stronger.

Genetics also have some influence on esper powers, and DNA can be used to determine esper powers. The very existence of the Parameter List and its ability to predict the future development of an esper before even passing through the Power Curriculum Program might be due to this fact, especially as they used it to get the DNA map of a future Level 5 for cloning ahead of time. Another manifestation of this is how siblings tend to get the same or similar powers: the Tobio twins have the exact same power, the Yumiya sisters have the same power but at different Levels, and Acid and Counselor both have oxygen-related powers. And, while they are not true siblings, there are no clones, or Sisters, of Misaka Mikoto with non-electrical powers. This is not an absolute rule: for example, the Gokusai sisters, or at least Kaibi and Amazora, have completely different powers. The triplets Ichika, Futaba, and Mitsumi likewise each have a different power. Yugure Kanaria and Yugure Tsumebakei also have different abilities. It may be that the possibility of similar and identical powers is weaker for ordinary siblings and fraternal twins than it is for identical twins and clones, who share the exact same genetic makeup.

Academy City's curriculum begins at 5-years-old at the earliest, and hormones generated during puberty and adolescence are considered critical to esper development. This might explain the prevalence of espers of kid and teenage age. In fact, it seems that is impossible to become an esper if one is an adult, to the point that the existence of adult espers is seen as improbable. So far no adult esper have been shown to exist, aside from those who used various means to artificially get esper powers, like Kiyama Harumi with Level Upper, Kihara Gensei with Exterior, Houjou Seigo with Ideal, and Kihara Byouri with her Equ.DarkMatter implants.

Ultimately, espers are considered only a byproduct of the Power Curriculum Program on the way to reach SYSTEM, with the reasons and mechanisms behind their existence being the actual objective of the city's scientists. Aleister compares espers to papers changing colors in solutions of different acidities: the interest is in why they changed colors and if it can be manipulated, not the colors themselves. Essentially, espers are a means to an end, not the end itself.

Power Curriculum Program
A person enrolled in this program is called an esper and, through a series of drugs usages and experiments, will be cut off from regular reality and enabled the capacity to substitute it with their own. Espers are ranked according to their System Scan results, which evaluates six attributes to determine the rank of an esper: Precognition, Clairvoyance, Psychometry, Telepathy, Psychokinesis, and an unknown sixth one. It is stated that Level 0 espers barely have enough influence to pass the curriculum's grading exams.

Any individual can use the curriculum to acquire powers, such as Misaka Mikoto, who started out as a Level 1 and worked hard during her training to become the 3rd ranked Level 5 esper in Academy City. There are exceptions of course, as with the case of Level 0s. Furthermore, with the Parameter List, it is apparent that esper potential is limited by various factors. This has resulted in researchers determining that it would be wise to focus on developing an esper whose ability is worth more to the city and whose training is predicted to be more resource efficient than that of another person's.

Information regarding the students enrolled in the curriculum, such as their abilities, their level and a brief description of them, is available in the Data Banks of Academy City. Furthermore, certain espers, such as Kamijou Touma, have security protocols in place to ensure that the truth of their abilities is classified.

According to Uiharu Kazari, the name of an esper ability, such as Electromaster or Telekinesis, is decided by the school that its owner is enrolled in. Only under specific conditions can the name of an esper ability be decided by its owner, such as the Railgun. Railgun ' s editor Ogino Kentarou further elaborated later that there are three types of names for abilities: public ones, the ones that the esper themselves applied for and registered, and self-declared names. It is unknown, however, as to what exact conditions an esper must meet to officially name their own esper ability, though its uniqueness may be a factor.

Currently, only Academy City can create espers, although others have tried, such as during the Stargate Project.

Gemstones and speculation
A Gemstone esper is an individual who can emit AIM without requiring participation in any power development program. Gemstones are the beings that Index likely referred to as having "talent"; the envy of their abilities from their peers is what led to the creation of magic. There are currently 50 confirmed Gemstones in the world.

In extension to this, it has been speculated that there may be people who have not realized that they have powers, or that their certain propensities or idiosyncrasies, as subtle as good looks or good penmanship, may actually have this power.

Many Academy City students are aware of Gemstone rumors, but treat them as urban legends. This is due to many feeling that it is unfair for esper powers to be gained without having gone through the Power Curriculum Program to attain them. Currently, Sogiita Gunha, who is the strongest Gemstone, and Himegami Aisa are the only two known Gemstone's in Academy City. Kamijou Touma, as mentioned by Kumokawa Seria, does not classify as a Gemstone esper as due to his powers being unrelated to AIM; it is believed that Imagine Breaker is beyond the current understanding of Academy City researchers.

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