Deflector shields

In fictional works, a force field, sometimes known as an energy shield, force shield, defence shield or deflector shield, is a barrier made of energy or particles. It protects a person, area, or object from attacks or intrusions. This fictional technology is created as a field of energy without mass that acts as a wall, so that objects affected by the particular force relating to the field are unable to pass through the field and reach the other side. This concept has become a staple of many science-fiction works, so much so that authors frequently do not even bother to explain or justify them to their readers treating them almost as established fact.

There is ongoing scientific research into real force fields, primarily to protect against radiation.

Science fiction and fantasy avenues suggest a number of potential uses of force fields

The capabilities and functionality of force fields vary; in some works of fiction (such as in the Star Trek universe), energy shields can nullify, or mitigate the effects of both energy and particle (e.g. phasers) and conventional weapons, as well as super natural forces. In many fictional scenarios, the shields function primarily as a defensive measure against weapons fired from other spacecraft. Force fields in these stories also generally prevent transporting. There are generally two kinds of force fields postulated; one in which energy is projected as a flat plane from emitters around the edges of a space craft; and another where energy surrounds a ship like a bubble.

The concept of a force field goes back at least as far as the 1920s, in the works of E.E. 'Doc' Smith and others; in William Hope Hodgson's The Night Land (1912) the Last Redoubt, the remnants of an humanity shelter is generated by something very like a force field.

In Isaac Asimov's Foundation universe, personal shields have been developed by scientists specializing in the miniaturization of planet-based shields. As they are primarily used by Foundation Traders, most other inhabitants of the Galactic Empire do not know about this technology. In an unrelated short story Breeds There a Man...? by Asimov, scientists are working on a force field ("energy so channelled as to create a wall of matter-less inertia"), capable of protecting the population in case of a nuclear war. The force field demonstrated in the end is a solid hemisphere, apparently completely opaque and reflective from both sides.

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