Psionics is a broad field that encompasses the study and practice of using the mind to cause paranormal phenomena. It includes such practices as telekinesis, telepathy, and precognition. Those who practice psionics are called psychics. Psionics are commonly incorporated into works of fiction, especially in role-playing games such as Dungeons and Dragons®.
The term psi originated in 1942 with B.P. Wiesner and Robert H. Thouless. They wanted a word that would describe both extrasensory perception (ESP) and psychokinesis. ESP is the ability to sense things that are beyond the reach of the five senses, and psychokinesis is the ability to influence the physical world with the mind alone. Later, science-fiction editor John W. Campbell Jr. coined the term psionics in the February 1956 issue of his magazine, Astounding Science Fiction.
The word is a fusion of psi and electronics. Campbell wished to communicate the concept of mental powers working as reliably as electronic machines. In science fiction, psionics are generally treated almost as magic, and given very little in-depth explanation. The mind, writers tend to say, simply has more power than the common man would guess. Psionics just work, just like a light bulb or other electronic device.
There are two distinct areas of psionic study and practice. Psi-gamma, also known as passive psi, involves such mental feats as precognition and ESP. It is considered passive because it does not cause any direct change in the environment.
Psi-kappa, on the other hand, is commonly called active psi. It concerns mental abilities, such as telekinesis and transvection, that directly manifest themselves in the physical world. While precognition supposedly grants the user the ability to perceive events before they occur, it does not have any visible physical effect. Telekinesis, though, is said to allow the user to manipulate physical objects with only his mind, and the use of transvection is supposed to grant the power of levitation.
The reality of psionics is a much-debated topic. Most scientists have placed the field completely in the realm of the absurd, though there are many who either speculate about the possibilities or truly believe in the innate capacity of the human mind to accomplish feats far beyond the mundane. Self-proclaimed psychics often work to capitalize on their precognitive or clairvoyant abilities, real or imagined. Their claims often do not come true, causing many people to strongly doubt the psionic abilities of the mind. These doubts, however, are unlikely to dissuade the many who truly feel that the human mind has a vast amount of untapped potential to do great things.