Force-Field Door

Keep it down in there! We barely have enough budget to reuse old Special Effects!

"I just wanna get it on record that using force fields for doors in a space prison... is a bad idea. You know what would have been better? Regular doors, with locks! Locks that don't open when the POWER goes out!"

— Space Warden Cave Johnson, Portal 2

A standard way to bar entry or exit for characters in Speculative Fiction is to use a Force-Field Door. It may be made of Some Kind of Force Field, glowing bars of Pure Energy, concentric Instant Runes, or what have you. If touched, it may harmlessly shock or dematerialize the appendage doing the touching. Sometimes, especially if the field is invisible until touched, it leads to amusing situations where characters run face first into the field.

Aside from Rule of Cool, the advantage of such a setup is usually that it is immune to physical attack, or that it can contain Starfish Aliens that could phase or shape-shift their way through ordinary doors.

Of course, the flaw in this immaterial marvel is it usually requires an outside energy source, or can be interfered with by using powerful ECM^note Electronic Counter Measures or MCM.^note Magic Counter Measures So the hero can traipse past these obstacles by pulling the proverbial plug on it. Worse is when the outside energy source is on the outside of the Force-Field Door, making disabling it as easy as beating up some guards and blowing it up.^note Which may actually be a challenge if guarded by Elite Mooks or the like. Or blowing a hole in the wall on the side, whichever is easiest. For some reason, the jailers rarely use physical doors outside the field (or wrapped in the field) as a backup in case of power failure.

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There is a small amount of justification in this trope. Force-field doors are very easy to use when you actually want to release someone at some point. Regular doors are just as vulnerable to blowing a hole in the side of the room. Having a system that fails open or fails closed is very much dependent on what you want the system to do.

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Examples:

Comic Books

• Green Lantern: The Lost Army: The light pirates' prison cells are each kept closed with a force field. B'dg takes advantage of the logical problems with such a system by disabling every door at once with a tiny, well-placed explosive.
• Legion of Super-Heroes: In Legionnaires #22, the Planet Hell prison has force-field doors on the cells. When the Legion and Workforce get locked up by the escaped prisoners, Karate Kid is able to find a weak point in the field, which shorts it out when struck.
• Superman storyline The Girl with the X-Ray Mind reveals Kandorian prison doors are made of glowing bars of translucent energy. Supergirl villain Lesla-Lar somehow short-circuits her cell's door, though, and breaks free.
• Wonder Woman:
  • Wonder Woman (1942):
    • Judgment In Infinity: The small cells the Adjudicator imprisons Wondy and the other heroes in have clear doors that look like some sort of thick glass which even a kryptonian's strength can't budge but which he can put his hand through, and which Diana realizes her lasso can pass right through due to the fact that they're made of an energy field and not actually a solid.
    • The Ytirflirks toss "Glitch" in a cell that has "bars" made up of glowing energy that are painful to touch and turn off with the press of a button.
  • Wonder Woman (1987): Circe's Tailor-Made Prison on Themyscira is essentially a magical version of this. Her cell is a beautiful garden planted with and circled with moly, a plant that cancels out magic which weakens her, ensures she can't use her magic and which she and other magical beings cannot physically pass when it is planted in thick rows like those around her garden. She escapes when the Olympian power holding the island aloft is broken and the garden is destroyed.

Fan Works

• In Hellsister Trilogy, Darkseid bars access to the cell holding Highfather's daughter with an invisible energy wall which is sturdy enough to withstand a Kryptonian's blows.

Films — Animation

• The cell blocks in Final Fantasy: The Spirits Within. So naturally, when the city's power grid goes down, so do the "bars" in the cells.
• Monsters vs. Aliens: Gallaxhar puts Ginormica in a force-field cage... which she then tears apart with her bare hands! Makes sense, as she is full of Unobtainium, which is more powerful than anything Gallaxhar has.
• Titan A.E.: Cale is thrown into one of these energy jails by the Drej (whose use of them is Justified: everything they build is made of force fields). It seems inescapable, until Cale realizes that the Drej phase through their own energy barriers all the time, and manages to work out how to do it himself.

Films — Live-Action

• Battle Beyond the Stars. Shad is being held captive by a Mad Scientist, but sweettalks his beautiful daughter into letting him escape. She orders the android with them to step into the "captor grid" that guards the door, causing it (and the poor android) to short-circuit.
• Guardians: Kuratov imprisons the three heroes in his lair behind a magnetic forcefield. When Major Larina comes freeing them, she just shoots the generator that's on the outside to shut it off.
• Nightlife, a 1980s vampire TV movie starring Maryam d'Abo and Ben Cross, features a doctor jury-rigging a prison cell for a vampire by hanging ultraviolet lamps above the only doorway into a room, as well as on the ceiling a few feet down the hall in either direction. If the vampire crosses the beam, he bursts into flames. See it here.
• In The Phantom Planet, the titular planetoid uses Star Trek-esque energy barriers for their prison cells, which hold an enemy alien captive. When the power goes down, the prisoner figures out he's free because the rocks he'd been flinging at the forcefield suddenly stop getting vaporized.
• Star Trek:
  • Star Trek V: The Final Frontier deserves special mention. When Kirk and company are held in their own brig, complete with force-field door, they hear tapping on the rear wall. They slowly piece out the Morse Code message: "Stand back". Which they do just before their ally renders the force field moot with high explosives.
  • In Star Trek: Generations, Soran protected his missile launch site with a massive force-field wall. Fortunately, it didn't penetrate the ground, which allowed Picard to bypass it through a tight rock arch it happened to rest on. Also an inversion, as Soran is the one inside the force field.
• Star Wars has several, such as the barrier that forces Obi-Wan and Darth Maul to wait momentarily before their battle in The Phantom Menace. Nearly every large starship in Star Wars has some part of the hull, usually a hangar, that's open to the vacuum of space. How do crew members breathe and not get sucked out into the void? Force fields. Seen in Revenge of the Sith when Anakin blasts the force-field generator over a Separatist battleship's hangar bay and air starts rushing out until a physical door closes over it. Rogue One prominently featured a planetary shield gate which is slammed shut on The Cavalry until they break the gate by pushing a Star Destroyer into it.
• The cell doors in TRON are beams of energy. Admittedly, they are already in the computer system and everything is energy, but there are still solid objects.

Literature

• Robert A. Heinlein's Have Space Suit – Will Travel. When Kip and Peewee are on the planet Lanador they find a People Zoo with several persons held behind force-field doors.
• In Brian Aldiss's story "Our Kind of Knowledge", the humans imprison their captives in a double cage: force fields and physical bars. The prisoners wonder why they'd bother to use bars if the force field really is impenetrable, and correctly deduce that the bars aren't what they seem.
• In Isaac Asimov's novel The Stars, Like Dust, the prison cells aboard a Tyrannian warship don't have doors, but instead "a force field stretched from side to side, top to bottom". This field is described as having "a tiny resilience" when touched, causing a tingling to the hand, and being completely impenetrable by material objects (though the beams of energy weapons — such as the guard's neuronic whip — will pass right through the field).

Live-Action TV

• In Agents of S.H.I.E.L.D., Skye has to visit a Boxed Crook, former agent Grant Ward, in a cell with one of these. It can go opaque or soundproof at the push of a button. Skye Lampshades one of the problems with this trope when she makes absolutely sure that there's no button she can push to accidentally turn it off.
• Blake's 7. In "City At The Edge Of The World", the Villain of the Week forces Vila to break through a door to a vault that he's convinced has enormous wealth. Vila works out that the door is actually a disguised forcefield — any force used against it only reflects back at the attacker (the villain gets his just deserts when he tries blasting through with a laser cannon). Meanwhile Vila and the Girl of the Week have gotten into the vault, only to finds it's a long-range teleporter to a distant spacecraft, where they'll live only as long as the oxygen that was transported with them lasts. When they don't die of asphyxiation, Vila has a "Eureka!" Moment that the spacecraft has reached its destination, and the wall is another disguised forcefield door with the air seeping in from the outside world.
• In the Firefly episode The Train Job, in the intro, Mal is thrown through what is evidently a force-field window: it vanishes as he passes through it, before reappearing a moment later. Assuming it performs the actual function of a window (keeping outside air out, and inside air in), it's most certainly an example of this trope, but they're never seen again.
• Space: 1999: "The Metamorph" has a classic Force-Field Door for the prison cell on the planet Psychon. Normally invisible, it emits a brief flash that stun the prisoners when touched.
• Stargate:
  • Stargate SG-1: "Abyss" features an interesting variant — a prison cell that uses the force of gravity as its "Force-Field Door". The cell is a long corridor with a dead end hooked up to an Artificial Gravity generator. When this is turned on, the end of the corridor becomes the floor of a deep pit, thus preventing escape for anyone inside (and ensuring a painful landing for an unprepared prisoner). When turned off, the "pit" becomes a corridor again, and guards can walk in or out. The resulting perspective shifts allowed for nice little Camera Tricks. The flaw is the same as that of any Force-Field Door: cut the power, and the prisoner can simply walk out.
  • Stargate Atlantis:
    • Atlantis has one built into its Stargate, serving the same function as the Iris on Earth's Stargate, with the extra advantage that it can't be overheated by firing exotic weapons through the Stargate (something Earth's Iris has had to deal with).
    • The city also has holding cells with energy shields covering actual bars. Surprising coming from the Ancients, who were usually very self-confident (case in point, a force field is the only thing holding the air inside Atlantis when it's in space).
• Star Trek:
  • Cell doors in Star Trek: The Next Generation, Deep Space Nine and Star Trek: Voyager are energy fields. Similar to the Star Wars example above, forcefields are also used for semi-permeable doors in shuttlebays, keeping air in while allowing the shuttles to pass through. In this case, they're at least sensible enough to have a physical door which is kept closed until the shuttles need to be deployed.
  • One Star Trek: The Next Generation episode "We'll Always Have Paris" had the bar variant in Dr. Manheim's lab.
  • Odo from Deep Space Nine had to be held in a room surrounded entirely with force fields, to keep him from escaping in his liquid form.
  • Add Star Trek: The Original Series, e.g. "Assignment Earth".
  • Star Trek: Voyager (in general a frequent offender with this trope) actually has an episode in which Voyager is temporarily converted into a Prison Ship, transporting a large number of dangerous alien prisoners in a converted cargo bay. Of course, all the cells added to the bay have Force-Field Doors. Predictably, a Standard Starship Scuffle ensues, and, lo and behold, the very first victim of Subsystem Damage is the cargo bay's power... The Oh, Crap! expressions on the bridge crew's faces when they learn of this are priceless. "Oh, woe, if only there was some other way we could have locked up those prisoners!"
  • Star Trek: Enterprise, being set in The 'Verse's past, is the exception and has a good old-fashioned solid door for their brig, made out of some reinforced transparent material. It seems to work just as well as the force-field doors on all the later Enterprises... Malcolm did actually manage to cobble together a working forcefield in one episode, which surprisingly held up.

Tabletop Games

• Dungeons & Dragons:
  • Adventure S3 Expedition to the Barrier Peaks. The spaceship's police headquarters had cells with three normal walls and one force-field wall.
  • D&D in general likes its magical force wall/cage effects. Depending on the edition, though, this can be justified in that those don't actually depend on an external power source and can be effectively indestructible if the exact right countermeasures aren't at hand, making permanent versions potentially actually superior to mundane physical barriers. In some editions, they are even among the rare few spells immune to Anti-Magic.

Video Games

• In Arcanum, Arronax was captured by the Big Bad and kept in a magical force-field capsule barely larger than his body for two thousand years.
• These appear in Batman: Arkham Asylum. They must be turned off before Bats can go further.
• The Castles of Doctor Creep has the force field as one of the many obstacles you face. The force field blocks the player (your character will stop just short of touching it), the monsters, and shots from any Ray Guns. Force fields start active, and they're turned off for eight seconds by a corresponding button. Once time is up, the force field(s) that the button shut off will reactivate and could trap the player on the wrong side (requiring a suicide).
• These show up occasionally in the Crash Bandicoot series of games. Typically in the Warp Rooms, barring off access to later chambers until you clear the one before it.
• Dark Souls features magic barriers that bar the Chosen Undead from entering the Duke's Archives, the lower section of the Tomb of the Giants and the section of the Demon Ruins just before Lost Izalith until they acquire the Lordvessel and place it at Firelink Altar. Similar barriers will also serve to isolate a character within a certain area if they're being invaded or have entered another player's world.
• Dishonored has force fields (called Walls of Light) that zap to ash anyone/thing unauthorized that tries to go through them. There are plenty of ways to circumvent them, however; there's usually an alternate entrance, you can remove the power source, you can rewire them to let you through and obliterate guards, and you can just throw stuff through the field until it runs out of power. One particular odd form of the latter is summoning a swarm of rats and guiding them into the wall. Two expensive ways to get through them involve Demonic Possession of a guard who is authorized and hop across that way, and the other is to use the advanced version of Bend Time to literally stop time and cross without fear of being zapped.
  • Please note that your basic Blink power is a Flash Step, not a teleport - you still traverse the space between the start and end points of your jump. Thus, attempting to Blink through a powered Wall of Light will result in your immediate demise.

• In Half-Life 2 some of the obstacles included energy fields to which you needed to shut off the power to get past. Often by literally pulling out a (inexplicably large) wall plug. These fields also allow combine troops (and trains) though while preventing Gordon and his rebel friends access.
• LEGO Legends of Chima Online: Various sections of the map are sectioned off with gates made of a shimmering energy field. A Sonic Boomer can temporarily shut off the energy field and allow a player to pass through.
• In Metroid games, doors are, with one exception, surrounded by force fields. These are always Color-Coded for Your Convenience and thus a Broken Bridge till you collect the right upgrade. The Prime series actually justifies the door-shields: the door were set up to separate distinct areas from each other. The doors are actually motion-activated, opening when a sufficiently large life-form approaches it, but to prevent the doors opening and closing ceaselessly for the indigenous life, the force-field was set up, which could only be deactivated by an energy weapon from a sufficiently advanced species. It wasn't so much to keep people in and out of certain areas (though that's inevitably what they do...to Samus), but rather to prevent wear and tear from constantly opening and closing.
• PlanetSide 2 uses forcefields in lieu of doors. Every base has impenetrable shields around the spawn building; at large facilities, these can be taken out by blowing up the generator that powers the spawn tubes. Other uses of shields are to protect vehicle garages — which often have the generator on the outside - or to delay attackers from capturing the base's control point. Planetside 1 used far more reasonable physical doors for pretty much every situation, only using force-fields doors for the vehicle gateways in facility walls.
• In the Perpetual Testing Initiative for Portal 2, an alternate Cave Johnson learns the hard way why these things are bad idea in a space prison — especially when you consider power outages.
  Cave: Man, those blue force fields looked good, though. Every time I saw one, I thought, "Wow! I am in space." Still, though... A door made out of paper would have been better in the long run. Would have at least slowed 'em down for a second.
• Quake II features doors that are red, yellow or blue force fields. Usually player can find a way to switch them off via terminals or buttons.
• In Raidou Kuzunoha vs. King Abaddon Dahn and his rogue Fukoshi are imprisoned in one. The "forcefield" can't be seen through, but the unoccupied cells in the same room have backup bars. (The forcefield is in place to block their insect summoning whistles.)
• Common in the Ratchet & Clank series. Sometimes Ratchet (or Clank) has to step on a button to open them, sometimes he has to trick or persuade some other character to step on the button, and sometimes he has to destroy the mechanism.
• Shows up a lot in the modern Sonic the Hedgehog games. They usually require you to flip a switch or destroy an encounter's worth of enemies to drop them. Other puzzles revolve around activating these to use as a walkway and sometimes even navigating mazes made entirely of them.
• Star Wars Legends:
  • In Jedi Knight: Jedi Academy, one mission involves escaping from a prison where an enemy has thrown Jayden. Each prison cell has four walls but no doors. The ceiling is a force field. Smart design, considering most people can't jump that high. Not smart when you put a Jedi (who can jump that high) in one of these cells and then let him out to play the most dangerous game with him.
  • Knights of the Old Republic:
    • Both games feature quite a few force-field cages and doors. Some of these require you have certain members in your party before you can pass through them (e.g Jolee to get down to the Lower Shadowlands on Kashyyyk).
    • In Knights of the Old Republic II: The Sith Lords, the Exile, Atton, and Kreia find themselves in force cages repeatedly, which Atton lampshades. The fields cause "only mild electrical burns" when touched.
• In Superhero League of Hoboken, Dr Entropy protects his first dastardly device behind a force field... but while the generator is placed on the inside, its power cord is plugged into an outlet on the outside, allowing the heroes to disable the field with one swift pull.
• The Talos Principle: Most puzzles feature at least one of these. They appear as blue barriers and can be deactivated pointing a jammer at them, putting some weight on a nearby pressure switch, or pointing a laser of the appropriate color into a nearby receiver.
• Unreal has them all over, as well the consequences of turning off the power...
• A standard in Warcraft III, turning these off is often a matter of killing the generator of boss powering them.
• Warframe features these heavily on both Corpus and Grineer ships. The former will deplete your shields, and fling you away from the door, as if you were struck by a shockwave, and need to be disabled by shooting (or staying out of sight of) security cameras, and the latter will proc Magnetic damage on you, draining all of your shields and energy, and are disabled by shooting ID scanner over the doorframe.
• XCOM: Enemy Unknown has the aliens use force-fields for their doors and protection for their Elerium engines which the Humans incorporate into their own design.

Webcomics

• In El Goonish Shive, Raven considers it "standard lockdown procedure" to put up force fields sealing off all the doors and some of the hallways when his school is under a magical threat. Not that it stops Abraham, however.
• Quentyn Quinn, Space Ranger (an IN SPACE! spinoff from Tales of the Questor):
  • During an arc skewering Star Trek, the main character is placed in a cell guarded by a force field and discovers he's been furnished with a replicator that can produce any food or drink he wishes. (Something the actual Trek examples didn't have, by the by.) He fabricates a pitcher of water and shorts out the door. You can see it here.
  • Earlier, they entered the shuttle bay through a force field, much to Omnibus's exasperation.

Web Videos

• The CollegeHumor: Troopers episode "Forcefield" has two bungling prison guards trying to convince their Princess-Leia-Expy prisoner that yes, her cell entrance is still blocked by an invisible forcefield.

Western Animation

• In Animaniacs, the "glowing bars of energy" version was used in a futuristic Buttons and Mindy short for Mindy's playpen. She had no more difficulty opening it than she did the regular version.
• The supervillain prisons in The Avengers: Earth's Mightiest Heroes use this kind of door.
• In the DuckTales episode "Armstrong", Armstrong sticks Scrooge and Gyro in a closet, behind a force field.
• Kaeloo: In Episode 105, the door leading to the magical staircase is a force-field door. Only the Pure of Heart may pass through it; anyone who isn't pure gets an electric shock.
• The Star Trek: Lower Decks episode "Temporal Edict" depicts the main characters repairing these doors in the Cerritos' brig; Mariner tests their strength with a phaser.
• Steven Universe: The cells on Peridot's ships in "Jail Break" are a force-field that (temporarily) vaporize gems' physical bodies on contact. Only one thing they didn't account for — the cells are only designed to hold the projected Gem bodies. Steven's organic form has no problem walking straight through and can block the field projector to let his friends out.

Real Life

• Plasma window. No, really.
• Considering that atoms are mostly empty space, and only feel solid due to the strong negative charge present on their surface (such that it is) which repels other atoms in a similar manner to what happens when you try to touch the south poles of two magnets together, ordinary doors are technically examples of this trope—only, you're just as much force-field as they.
  • Indeed, Cecil Adams suggests that the easiest way to hold a static sheet of electrons in place would be to build a wall.

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