In spite of the distinction typically drawn between flesh and machine, the human brain is, in fact, an electronic computer: it uses electrical impulses transmitted through logic gates (neurons) to process information. One way the electromagnetic character of the brain can be seen is in neural oscillations, more commonly known as brainwaves. Rhythmic electrical pulses constantly radiated through the brain to synchronize its various functions, measurable by electroencephalogram. These signals can be conceived as sort of like radio waves, signals by which the different parts of the brain talk to one another. Brainwaves are grouped into different types, named with Greek letters.

For an esper – a person with psychic powers – these oscillations are more than scientific curiosities. Espers can intentionally modulate the waves within their own heads, strengthening or weakening them to affect their cognition according to the natural functions of each wave type. When they project their psychic influence externally through resonant coupling, they can extend any of these effects out to other minds. Each of the six major classes of brainwave constitute a different field of study for espers, with its own set of abilities. A given esper will typically specialize in one or two of them, learning to amplify and project that frequency of their soul.

Delta

>4Hz. Low frequency but high amplitude waves generated during sleep. Amplification produces a sedative effect: an esper can cause themself to fall asleep in an instant at will, as well as modulate sleep in other intentional ways, such as waking up on cue, removing post-sleep grogginess, suppressing dreams, stimulating healing, reducing daily need for sleep, and even inducing unihemispheric sleep to remain half-awake at all times.

Although the delta wave’s function is relatively narrow, its various applications make it quite potent nevertheless. Delta users can easily maintain themselves in good health through efficient sleep, effectively have more time per day to carry out their plans, and if threatened can render attackers unconscious at a distance.

Theta

4-7 Hz. Waves associated with the encoding of memory, which increase when learning, navigating, dreaming, and meditating – they are related to (but should not be confused with) the “sleep spindles” of sigma waves during NREM sleep. By generating these waves, an esper can give themself perfect snapshot recall of information, alter memories of the past, pick up new skills quickly, boost creativity, and induce vivid dreams – or waking hallucinations, often psychedelic in character.

While theta users produce dazzling art and can help ease emotional disturbances in others, those same powers draw a special fear from other espers: they mean that one can never entirely believe their own sense of reality, or even entirely trust their own memories, which may have been modified through theta waves.

Alpha

8-12 Hz. The distinctions are subtle, but when over the motor cortex, waves of the same frequency band can also be mu or SMR waves. In all these cases, though, alpha waves suppress other activity in the brain, increasing when at (wakeful) rest and decreasing when actively engaged. As such, they’re associated with calm, relaxation, and a sense of joyful ease, of the type cultivated by jhana meditation. Generating alpha waves fills the mind with emotional euphoria and physical pleasure.

The ability to artificially induce joy in yourself and other cannot be underestimated: people will literally kill for another hit of an alpha user’s attention once addicted to it. The alpha user themself, on the other hand, may entirely drop out of society at times, having achieved an ouroborosian state of detachment from external desire – something akin to nirvana. Espers with this ability can use it to ambitious ends, though: their emotional stability makes them impossible to threaten, shame, or manipulate, as well as freeing them from the regrets that usually hold a person back from adaptably pivoting under changing circumstances. They carry themselves with the beatific grace of holy people, giving them an inherent charisma even when not using their powers on others.

Beta

13-30 Hz. High-frequency waves triggered by the performance of tasks: beta waves strengthen when one is alert, thinking, moving, and acting. Generating these waves improves focus, accelerates reaction time, increases problem-solving abilities, and elevates awareness of one’s surroundings.

Beta waves offer perhaps the most comprehensive ability set available to espers: beta users effectively have a “be better at everything” button in their heads, giving them near-superhuman capacity to exceed in any skill. However, this powerful stimulant effect tends to exhaust the brain when maintained for extended periods, so it must be activated sparingly.

Gamma

31-150 Hz. Very high-frequency waves that rhythmically wash over the brain as a whole, synchronizing its various parts into unity. Gamma waves are the mechanism by which the mind binds thoughts, emotions, and sensations together into a single coherent sense of self. Reduced gamma activity is a marker of schizophrenia, epileptic seizures spread through the brain by way of gamma bursts, and gamma waves can increase a hundredfold at the moment of death, inducing near-death experiences. By modulating them intentionally, one can dissociate into ego death, split one’s personality into subsets, or synchronize one’s sense of self with the frequencies of nearby minds, merging consciousness with them.

Gamma waves offer some of the strangest effects available to espers, and carry the greatest risk of unbalancing their psyches. Its most crucial capability is resonating brainwaves with those of other people, linking multiple minds into a single, composite entity: espers can use this to join their powers into overwhelming force, but doing so is a deeply intimate act on the level of (although not quite the same as) romantic contact. With sufficient training, it can even be extended to nonhuman animals, plants, or even inanimate objects, letting you “talk” to rocks on a geologic timescale and perform feats recognizable as telekinesis by incorporating nearby objects into your self-conception.

Psi

<150 Hz. Anything above the gamma range is considered a “psi” wave. These waves do not typically occur naturally outside of pathological cases, but are the telltale markers of an esper. Use of psychic abilities causes brain waves to elevate in frequency beyond normal levels, enhancing cognition in cryptic ways. Typically, psi wave frequencies map to factors of normal frequencies: that is to say, when using a beta wave power, the associated psi waves will measure at some multiplication of 13-30 Hz, with a similar wave form. Because evolution did not design the brain for such powerful signals, the use of psychic powers taxes the nervous system, expending significant calories and requiring rest after heavy use.

A handful of espers specialize into the use of psi waves themselves, rather than one of the natural types. This grants what are termed “metapsychic” powers: the ability to alter psychic processes at the base level. Although the field is nascent and remains an area of active research, psi users have demonstrated suppressing and enhancing psi abilities in themselves and others, as well as activating dormant abilities in non-espers, and – most terrifyingly – removing the capacity for psychic powers from current espers.

Omega

??? Hz. The existence of omega brain waves remains theoretical. According to handful of fringe psychic researchers, somewhere above the 1000 Hz range an esper could synchronize with the brain waves of the universe itself, or perhaps cosmic entities beyond it. Others counter that the universe would, if conscious as a whole, exhibit a neural-analogue of incredibly low frequency instead, synchronized with the motions of heavenly bodies in their stately gravitic waltz, therefore putting the omega wavelength in the fractional hertz range. Either way, if it exists, achieving an omega state could potentially access omniscient insight or phenomenal power over reality itself – if it didn’t burn out one’s brain first.