Shields are widely used in science fiction to protect spacecraft and persons - see, for instance, "Maximum Wrap" by D. Galanter. They could be produced by strong magnetic fields. Magnetic shielding against radiation, and the use of magnetic fields as "sails" for real interplanetary missions, are currently under discussion. We can deflect electrically charged objects using electromagnetic fields, leading to concepts for protecting space travellers from cosmic radiation. That's the physics trick we know that resembles the powerful special effects of the Enterprise's shields. Neutral particles and objects cannot be deflected by magnetic shields.

In "Star Wars" the strong shields were repeatedly used to shield a planet, a battle cruiser or a space ship. The rebel shield over Hoth had to be lowered to allow the egress of departing ships and the ion cannon shots against the Imperial blockade in "The Empire Strikes Back". If magnetic shields were used as deflector shields, they would have to be lowered to allow a ship to depart, as the strong magnetic field would interfere with the on-board electronics. Shields in "Star Wars" are usually associated with spacecraft, but there are several examples of devices involving shields on a smaller, personal scale: in "The Phantom Menace", Federation destroyer droids had built-in ray shields, and the army of the Gungans was also outfitted with portable in-atmosphere theatre shields. Personal magnetic shields could be made using magnetic dipoles or coils. Superconducting coils could generate magnetic fields that are strong, but would have to be actively cooled to work at room temperature, which is a big effort. Strong magnetic fields could also be used like a big sail, catching the plasma naturally found in the solar wind and interstellar medium like a cotton sail catches the wind. Magnetic sails could also be used to accelerate or decelerate a spacecraft on an interplanetary mission.

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