Deflector Shields: Difference between revisions

[[File:Voyager_shieldVoyager shield.jpg|link=Star Trek: Voyager|frame|Shields at 20% and holding!]]

Also called "[[Force Field|Force Fields]]s", these are invisible (or, if the budget allows it, barely-visible) energy barriers placed around objects to protect them from harm.

Most common around space ships, but also seen around bases and -- veryand—very occasionally -- [[Barrier Warrior|individual people.]]

An energy barrier can zap or repel anyone who touches it, or can simply behave like an impenetrable wall. It's often represented in the form of a [[Beehive Barrier]] or another [[Hard Light]] construct. In practice, this is somewhat less scientifically feasible than [[Energy Weapons]], but not by much, at least in the way it is usually depicted -- adepicted—a strong electromagnetic field really can be used to deflect [http://www.projectrho.com/rocket/rocket3x.html#particle particle beam] weapons or railgun/coilgun slugs. A better example is the Earth's magnetic field which safeguards us from charged particles in the solar wind. NASA and ESA are actually researching how to reproduce the effect on future interplanetary spaceships, to protect Mars travellers from cosmic radiation.

Unfortunately, the alternative is not much better; though many writers choose to omit energy fields these days, they neglect that, without some kind of continuously regenerating barrier, a ship traveling at relativistic speeds (say, more than half the speed of light) isn't going to get very far before micrometeors and particulate matter punch holes through its armor, however thick it is. There are feasible alternatives though -- selfthough—self-repairing armour seems to be a common feature of bioships, or, since the ship only needs to be well-protected at the front, a ''fountain'' can be used while the ship is accelerating -- mostaccelerating—most of the voyage may be spent accelerating at .01g, and then when you arrive you just need a way to decelerate quickly while your armour lasts.

Note that if a shield deflects not just [[Frickin' Laser Beams|rays]] but massive objects, Newton's third law kicks in, as it requires the force stopping the projectile to be equally applied ''to the shield'' -- and—and if it has negligible mass, this means ''directly to the shield generator'', bypassing armor and everything. So if the shield is not ''very'' thick and/or does not distribute load over a ''very'' large area, its not a missile-stopper: any massive object moving at a modest (on an orbital scale) speed will pass through the shield if their interaction is limited to the safe level or crush the shield emitters and ''then'' pass through if it isn't. So bonus points if the shield either mostly disintegrates incoming projectiles [http://www.projectrho.com/rocket/spacegunconvent.php#Kinetic_Kill_Weapons~Effects so that armor deals only with dust] (i.e. acts as a rechargeable sort of [http://hitf.jsc.nasa.gov/hitfpub/shielddev/basicconcepts.html Whipple Shield]) or it's ''not'' a main defense against missiles and that pesky iron-nickel gravel, or both. Usually in these cases [[Kinetic Weapons Are Just Better]]. Unless, of course, the shield is [[Handwaved]] to stop kinetic energy as well.

Other issues involve a shield's interaction with the same effects passing ''from inside''<ref>it would need to either be asymmetric or able to open "windows" for firing weapons and any non-inertialess propulsion, with all problems this entails</ref> and lower-grade effects.<ref>if it blocks lasers, there would need to somehow be a method to only block radiation above a certain energy level or it would block visible light</ref>.

Shields are popular in fiction because it allows the [[Cool Ship]] to participate in battles without the inconvenience of having to spend the rest of the episode making repairs to physical armour and systems. In older or lower-budget movies and TV, they also eliminate the need to show battle damage on the ship; e.g. having your Ensign call out "Shields down to twenty percent!" can be a lot cheaper than showing a gash blasted in your ship's armor. The downside is that creators often have to resort to [[Explosive Instrumentation]] to provide combat casualties on a shielded ship. In somewhat-harder science fiction, shields are useful to overcome the seemingly overwhelming attacker's advantage--citiesadvantage—cities on planets can't dodge, so if there isn't some way to defend against space-launched missiles and kinetic projectiles, wars are going to be short and boring.

In [[Video Games]], deflector shields have a special use. They are effectively a way to justify [[Regenerating Health|regenerating hit points]], but only for a part of a unit's health. Shields get to regenerate, but if there is something beneath them, like armor, [[Regenerating Shield Static Health|the armor ''doesn't'' regenerate]]. Also, for many games where a target can take [[Subsystem Damage]], that won't start until you penetrate the [['''Deflector Shields]]'''.

Note that, despite the name, [['''Deflector Shields]]''' don't really need to ''deflect'' enemy attacks, in the sense that the attack will bounce off and possibly hit somebody else. It's more common for the attack to simply stop at the shield's edge, meaning that the attack has technically been ''diffused'' or ''absorbed''. (The term "deflector" comes from the proposed use of similar, weaker technology to deflect tiny incident particles of dust and debris while a spacecraft is flying at orbital speeds or faster. And ya gotta admit, "deflector shield" and "energy shield" sound [[Rule of Cool|cooler]] than "absorption shield".)

** The Mercurius Mobile Suit and Virgo [[Mecha-Mooks|Mobile Dolls]] from ''[[Gundam Wing]]'' had Planet Defensors, [[Attack Drone|Attack Drones]]s that generate a forcefield capable of blocking most ranged weapons. Their only weaknesses seem to be [[Frickin' Laser Beams|lasers]] and melee attacks, but this is usually offset by the Virgos' powerful beam cannons, their working in teams, and the rarity of weaponized lasers in the setting.

* ''[[Code Geass]]'' has two different versions, one for each of the major military factions. The MSV maser shields used by [[The Empire|Britannia]] appear on the [[Super Prototype|Lancelot]] as beam shields a'la ''[[Gundam]]'' before developing into full-on Deflector Shields and being applied to some [[Ace Custom|Ace Customs]]s and larger devices such as the [[Cool Airship]] ''Avalon'' ({{spoiler|and eventually the [[Kill Sat]] ''Damocles'' near series' end}}). [[La Résistance|The Black Knights]] develop the Guren Mk-II's radiant wave attack system into a shield called the Radiant Barrier and install it in their commander mecha and battleships in the second season. Worth special mention is the Shinkirou, protagonist Lelouch's [[Ace Custom]] machine: its Absolute Protection Territory uses an array of MSV maser shields that require on-the-fly coordination by the pilot, meaning that only someone incredibly intelligent can use it to its full potential (that being the strongest shield system in the ''Geass''-verse).

* The alien invaders and the title robot in ''[[Cannon God Exaxxion]]'' use force fields that are an offshoot of their [[Artificial Gravity]] tech. They have rendered most types of weapons obsolete, with the exception of [[BFG|BFGs]]s & melee weapons wielded by extremely strong combatants, the idea being that the only way to penetrate such a barrier is to focus more energy on a single point than the system can produce. Explosives don't work, as their energy is spread too thin & lasers are right out due to gravitational lensing.

** Ground-based shields, in ''Star Wars'', serve to prevent your force from having the living bejeesus vaporized out of them by orbital bombardment. That forces the enemy into a land engagement which you usually have a better chance of winning -- thewinning—the scenario that took place in ''The Empire Strikes Back''. ''Star Wars'' canon has two kinds of shields -- "energy" shields (a.k.a. ray shields) to repel energy blasts, and "particle" shields to repel physical objects. Shields consume a massive amount of energy, though, so if you're shielding something the size of a planet, you generally can only have one. This makes perfect sense in canon, but [[All There in the Manual|a systematic failure to explain it at any point in the movies]] left entire audiences going "What the hell?" when droids casually strolled through the shield that had just repelled tank fire in ''[[The Phantom Menace]]''. The confusion, and the length of the above explanation, also explain why so many writers prefer to just make their shields magical barriers that just ''work''.

** Gets around the above-mentioned Newtonian problem by draining energy from anything incoming. Energy beams are weakened, and projectiles lose kinetic energy and slow down. (Note that this makes the Field a zone around the ship rather than a thin bubble or wall.) The Field absorbs the drained energy, then gradually radiates it outward as heat--unlessheat—unless it absorbs too much energy, in which case it [[Phlebotinum Overload|collapses]], radiating all the stored energy inward ''and'' outward at once, destroying the shielded ship.

** your basic garden-variety 'conventional' shield, which effectively acts as an invisible wall -- thewall—the safest type to use if you're worried about civilians walking right into it;

** As a final point, the series also features literal 'deflector fields'...which actually aren't this trope at all, but rather [[Cloaking Device|Cloaking Devices]]s working for the most part in the visible spectrum (they get their name from the way they 'deflect' light around who- or whatever wants to remain invisible). They're seen most often on the personal scale, but ''can'' in principle be used to hide larger objects as well; it's just not normally worth the bother because somebody actively looking for those will likely not rely on optical sensors alone anyway and the energy of the field itself is quite detectable.

* Also from the mind of [[Larry Niven]]: his ''[[Known Space]]'' series features a "stasis field" -- though—though not technically a "deflector", since it was a field in which no time passes -- thatpasses—that can be used for everything from creating a knife (his "variable-sword" is a monofilament cord encased in a stasis field) -- to shielding a ship or spacesuit (see ''World of Ptavvs''). Larry Niven himself once stated that it got to the point where he had to find reasons NOT to use a stasis field as a solution for everything.

* In David Weber's ''[[Honor Harrington]]'' series, the "shields" (referred to as "walls" and "bands" in the novels) actually have a logical basis, given the way they are described to work. The ships have gravity drives; the effect of the drives manifests itself on the "top" and the "bottom" of the ships (called "bands" to differentiate them from the other "walls") -- where the effect is impenetrable. All ships above pinnace size also have "sidewalls" -- also—also areas of focused gravity, though not as strong as the top or bottom walls. A strong enough energy blast can penetrate the sidewalls, though with distortion and a lessening of power -- thepower—the bows and sterns of the ships are unshielded. Or at least were, until the protagonist's star nation develops "bow-walls". Tactics involves using enough missiles to get past the defenses of the opposing ships and letting loose with nuclear-bomb-pumped lasers. This is all a complicated rationale to have Napoleonic style fleet battles [[In Space]].

* In the ''Tomorrow War'' (rather [[Mohs Scale of Science Fiction Hardness|"hard"]] 'verse) by Alexander Zorich, shields are useful against [[Frickin' Laser Beams|rays]], but not kinetic weapons, which of course makes latter [[Kinetic Weapons Are Just Better|just better]]. Attempts to strap shields on a aerospace fighter the first time was one of the first book's plot lines, mainly on account of trying to make it work in an atmosphere -- apparentlyatmosphere—apparently, it was "solid" enough to mess up aerodynamics, but not enough to be used as a [[Hard Light]] element.

* Joe Haldeman's ''[[The Forever War]]'' has the "Stasis field." Only problem is that nothing inside can go faster than 16.3 &nbsp;m/s, rendering most projectile weapons useless, and any living thing not wearing special armor dies instantly when inside of it. Which means that inside of the field, it's a [[Sword Fight]].

* In ''[[Dragonriders of Pern]]'' at least big colony ships has shields elastic and -- ''large'' -- enough—enough to bounce away objects at typical meteor speed without turning them to fine dust. However, they have destructive mode as well, just set in deflection mode as more resource saving and obviously safer for shuttles.

** There are also the personal force shields they find in that freedom fighter base -- theybase—they activate only when hit by blaster fire, but then will protect the wearer from pretty much anything, up to and including lava. Unfortunately, apart from one use in the next episode, the few that our heroes manage to salvage are never used again after "I Shrink Therefore I Am," presumably because [[Bounty Hunter|Axicor]] had them destroyed the moment he discovered them.

** Also lampshaded when the commander of a Terran battlecruiser (a powerful yet unshielded warship) says: "Shields up, weapons online!" -- only—only to correct himself when clicked again -- "... not equipped with shields? Well then, buckle up!"

** ''[[Final Fantasy XII]]'''s cities are protected by a "Paling," a [[Magick]] force field projected by a massive crystal in the center of town, that lets travelers pass through but keeps hostile creatures (or attacks) outside. Once the Paling falls, the city becomes vulnerable to assault and invasion --orinvasion—or the stray airship that was just shot out of the sky.

** ''[[Final Fantasy X]]'''s Sin can protect itself with a gigantic spherical force field, which is effective enough to repel, overload, and destroy the Al-Bhed [[Wave Motion Gun|Wave Motion Guns]]s and then [[Sphere of Destruction|expand to disintegrate anything in the vicinity]]. Strangely enough, Sin fails to use this shield when [[High Altitude Battle|engaging the party and their airship]] --though—though it may have been holding back willingly at that point.

* A common feature in the universe of ''[[Beyond Good & Evil (video game)|Beyond Good and Evil]].'' There are both large [[Deflector Shields]], designed to protect buildings from airborne attacks from the [[Alien Invasion]], and smaller, personal shields used by both good and evil soldiers to prevent you from damaging them.

* In the ''[[X (video game)|X]]-Universe'' series, shields are the only viable defense--hulldefense—hull is very weak and damage translates to very expensive equipment getting destroyed.

* In ''[[Shin Megami Tensei: Strange Journey]]'', all of the Schwarzwelt Investigation Team [[Cool Ship|Cool Ships]] --thes—the ''Red Sprite'', the ''Elve'', the ''Blue Jet'', and the ''Gigantic''-- are—are equipped with a so-called "plasma shield." It's never made clear whether it's a shield ''composed of'' plasma or one that protects ''from'' plasma (seeing how the Schwarzwelt is, itself, surrounded by a plasma wall that disintegrates whatever it touches,) but not only is it explicitly enabled every time the ''Red Sprite'' jumps between dimensions within the Schwarzwelt, but presumably it's what keeps demons from tearing the ship to pieces while the Strike Team commandos are on a mission.

* ''[[Schlock Mercenary]]'' has "unifield shields" that use [[Artificial Gravity]] to distort the paths of incoming attacks. Warships invariably use "breacher missiles" that emit a gravity pulse to try and push back. The author [[The Rant|expounds at length in a]] [[Foot Note]] about how shields would realistically be best portrayed,<ref>since they are designed to obstruct energy attacks of all forms, including visible laser light, they should technically obstruct the view of the ships they enclose entirely, leaving battles fought between blobs of darkness where the stars are obscured</ref>, [http://www.schlockmercenary.com/d/20071214.html and how he portrays them with a distinct amount of artistic license.] He's also suggested that, if he doesn't have time, he would portray them realistically...

* The British Ministry of Defence [http://www.telegraph.co.uk/technology/news/7487740/Star-Trek-style-force-field-armour-being-developed-by-military-scientists.html is seriously pursuing the development of real deflector shields for tanks]. The tanks' armour would contain super-capacitors that store large amounts of electrical energy, and then release it in a brief, powerful blast when an incoming projectile approaches. The incredibly powerful, localized EM pulse would physically deflect the projectile. The capacitor would then rapidly recharge to prepare for another attack. Projectiles as large as rocket-propelled grenades and small missiles could be protected against in this way. The only difference from ''[[Star Trek]]'' -- style—style forcefields is that these deflectors would work in pulses, rather than running continuously. And they probably wouldn't do much against [[Death Ray]]s...

* ''[[Soul Eater]]'': Shinigami uses skull-shaped shields to defend against Asura, and at one point attempt to crush him into the ground. Kid gets a smaller version through Brew, which he uses to defend against Mosquito's attacks. Stein has a technique -- experimentaltechnique—experimental spirit body -- whichbody—which creates a human-shaped shield around himself. Used only once, but it's an example of soul wavelength being used to block attacks. Such is the versatility of souls in the series, it'd be unsurprising if the idea gets used again.

* One of [[Isaac Asimov]]'s ''[[Foundation]]'' series books has a man trading his personal shield -- resistantshield—resistant even to ray gun fire -- tofire—to one of the guards in exchange for a private viewing of the generator facilities on a planet. Oh, the shield works, all right, but only for one day.

* Another fantasy example is from the Death Gate Cycle, where the Patryns tattoo magical runes all over their bodies for magical protection. However, these aren't perfect shields -- inshields—in the second book, when faced against a giant monster, the main character's magical shield broke under the giant's assault with a tree trunk. The explanation being that the powerful blows caused cracks to form between the sigla that comprise the magical barrier, thus weakening and ultimately obliterating the shield.

* Mage-type Shades in ''[[Nie R]]'' can project a [[Sphere of Power]] around themselves or their allies that make them impervious to damage, or at least negate a very large fraction of it. Nier himself can call upon Weiss' Dark Wall spell, which can cast an invincible [[Instant Runes|rune-inscribed wall]] of limited duration in front of him --buthim—but ''only'' directly in front of him, and it's fixed in place once cast.

* Archer of [[Fate/stay night]] can summon one of these. Kind of a strange example, in that it's theoretically an actual physical shield that a warrior might carry--butcarry—but it's a legendary weapon that can deflect anything and he can summon it as a magical ability, so it works out to be more like [[Deflector Shields]].