A force field, sometimes known as an energy shield, force shield, or deflector shield is a concept of a field tightly bounded of significant magnitude so that objects affected by the particular force relating to the field are unable to pass through the central axis of the field and reach the other side. It is a concept popular in science fiction and fantasy works. Scientific research into energy shields is ongoing.
Scientific research 
A University of Washington group in Seattle has been experimenting with using a bubble of charged plasma to surround a spacecraft, contained by a fine mesh of superconducting wire. This would protect the spacecraft from interstellar radiation and some particles without needing physical shielding.
In 2008, Cosmos Magazine reported on research into creating an artificial replica of Earth’s magnetic field around a spacecraft to protect astronauts from dangerous cosmic rays. British and Portuguese scientists used a mathematical simulation to prove that it would be possible to create a "mini-magnetosphere" bubble several hundred meters wide, possibly generated by a small unmanned vessel that could accompany a future NASA mission to Mars.
Fictional applications 
Science fiction and fantasy venues postulate a number of potential uses for force fields:
- A barrier to allow workers to work in areas that can be exposed to the vacuum of space, keeping the atmosphere inside while allowing certain other objects to pass through.
- Emergency quarantine of an area afflicted by a harmful biological or chemical agent or occupied by enemy forces.
- The extinguishing of a fire by forcing the reaction to use up all the available oxygen in the confined space.
- As a shield from damage by natural forces or enemy attack.
- To create a temporary habitable space in a place not usually suited to sustaining life.
- As a security method to direct someone in a particular direction for capture, or to confine a captive in a particular area.
The abilities and exact functionality of energy shields vary; in some works (such as in the Star Trek universe), energy shields can stop, or mitigate the effects of, both energy and particle weapons (e.g. phasers) and normal projectiles, both natural and artificial. In the various series, shields function primarily as a defensive measure against weapons fire from other ships; these shields also generally block the use of transporters while active. Also, inside ships, force field generators can seal off ship atmosphere from the vacuum of space, as in the case of a hull breach caused by an attack or explosion. There are two kinds of force fields, one that is projected as a flat pane from emitters around the edges, and one that surrounds the ship like a bubble.
The concept goes back at least as far as the 1920s, in the works of E.E. 'Doc' Smith and others; and William Hope Hodgson's The Night Land (1912) has the Last Redoubt, in which the remnants of humanity shelter, protected by something very like a force field[original research?].
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 in the Galactic Empire do not know about this technology.
In Asimov's short story Breeds There a Man...?, scientists are working on a force field (defined as "Energy so channeled as to create a wall of matterless inertia,") capable of protecting the population in case of a nuclear war. The force field demonstrated in the end is a solid hemisphere, completely opaque and reflective (apparently in both directions).
The concept of force fields as a defensive measure from enemy attack or as a form of attack is popular in video games as well.
The ability to create a force field is a popular superpower in comic books and associated media. While only a few characters have the explicit ability to create force fields (for example, the Invisible Woman and Violet Parr), many can emulate it with other powers, such as Green Lantern's energy constructs, Jean Grey's telekinesis, and Magneto's manipulation of electromagnetic fields. Apart from this its importance is also highlighted in Dr. Michio Kaku's books (for example, Physics of the Impossible).
See also 
- Shiga, David (2006-07-17). "Plasma bubble could protect astronauts on Mars trip". New Scientist. Reed Business Information Ltd. Retrieved 2008-12-13.
- Shiga, David (2007-04-18). "'Deflector' shields could protect future astronauts". New Scientist. Reed Business Information Ltd. Retrieved 2008-12-13.
- Rincon, Paul (2007-04-18). "Space shield to block radiation". BBC News Online (BBC). Retrieved 2008-12-13.
- "esdjournal.com/articles/final/final.htm". Retrieved March 19, 2010. issue of the ESD Journal discussing report in Session 7: Special session, 17th Annual EOS/ESD Symposium, Sept 14, 1995. See also amasci.com/weird/unusual/e-wall.html
- Cosmos Online - Star Trek-style shields could become reality
Further reading 
- Andrews, Dana G. (2004-07-13). "Things to do While Coasting Through Interstellar Space" (PDF). 40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit. Fort Lauderdale, Florida. AIAA 2004-3706. Retrieved 2008-12-13. Unknown parameter
- Martin, A.R. (1978). "Bombardment by Interstellar Material and Its Effects on the Vehicle, Project Daedalus Final Report". Journal of the British Interplanetary Society: S116–S121.