Electromagnetic pulse

EMP, short for electromagnetic pulse, is often used in stories to take out anything electronic. Sometimes shown to be a temporary effect (especially when the Rule of Fun applies in games), it usually results in the permanent disabling of electronic systems.

Now for a more detailed explanation.

When a nuclear warhead explodes, it releases a LOT of gamma rays, which are photons with tons of energy. When these photons travel through air, they strip electrons off the air molecules as they zoom past. This is called "ionizing" the air. Because those photons are so very energetic, they do it over a very long distance and make a huge volume of ionized air.

Ionized air becomes a conductor. This means those stripped-off electrons, energized by the gamma rays, are free to move around in an electric current. Any change in current produces radio waves. And since the current is going from zero to huge in a very short amount of time, this means a large portion of the atmosphere becomes a MASSIVE radio transmitter, broadcasting noise at full power.

Radio waves have the generally useful property that they induce currents in conductive material (that's how a receiving antenna works). So whenever these MASSIVE radio waves hit something metal, like the wires inside your computer, they produce proportionally MASSIVE power surges. Ever had a piece of electronics destroyed when lightning hit your house? This is a similar effect, except bigger. And everywhere. At the same time.

As a bonus, the main pulse is followed almost instantly by secondary ones. The original nuke releases neutrons, which run into things and produce more gamma rays, which produce another wave of electrons. And after that, the Earth's magnetic field "heaves" a little when hit by all this stuff, and that magnetic effect can zap anything connected to really long wires.

Doesn't that sound like fun?

In particular, silicon transistors—the building block of modern electronics—are very sensitive to these power surges. The induced current burns and destroys them. They are so sensitive, in fact, it has been theorized that a single nuke, detonated in the right part of the upper atmosphere, could take out most of the unprotected computers in the United States. Also, it is theorized that a high-intensity EMP burst could destroy silicon transistor circuitry even if the device is turned off. Military hardware has to be specially shielded to withstand most of the effects. Interestingly, ancient computers from the 1950s would also be resistant; they were built with vacuum tubes, which can take the pulse a lot better than modern transistors, especially if they were powered down at the time. Also, it's possible that early transistors, which were made of germanium rather than silicon, might be able to withstand an EM pulse if the device was powered down.

If you want to do this zapping without the nuclear fallout, there are a few smaller weapons that can generate an EMP. Such a thing is usually a kind of single-use electric generator, which sends out its pulse when crushed by a conventional explosive. The pulse is far weaker, and can kill maybe an office full of computers. In case you wonder why the same explosive charge alone couldn't do it, a range can be extended by rigging up a generator to get a directional emission of microwaves instead of a plain magnetic surge. Getting a city-sized EMP without a nuclear bomb is not feasible with current technology; as to reusable variants, if we had the capacitors necessary to do that, we could also build practical railguns and laser rifles.

A more docile variant of EMP is "degaussing," which uses a varying magnetic field to remove magnetism from a metal object. Ships in WWII were degauused to make them less vulnerable to magnetic mines. Modern CRT monitors have built-in degaussers to eliminate color aberrations caused by stray fields. And bulk erasers, an even smaller and lower powered version of this, is used to destroy the data on magnetic storage devices (very popular with the BOFH).

When Hollywood talks about EMP, it can generally be filed under You Fail Physics Forever.

Examples of Electromagnetic pulse include:

Anime and Manga

• Highschool of the Dead features one moderately realistic EMP generated by a low-altitude nuke exploding over Japan.
• In Gundam Seed, ZAFT has the Gungnir System, which it deploys when they attack Panama - and then proceed to slaughter Alliance soldiers trapped in disabled mecha. Even the revenge-minded Yzak gives pause at this, hinting at his later Heel Face Turn.

Comic Books

• X-Men villain (and occasional ally) Magneto does this from time to time. Considering how flexible his magnetic powers are usually depicted as being, it's not completely out of the question. Storm has done it with lightning bolts which ... no.
• In the second issue of Global Frequency, one of the characters carries non-lethal weaponry, such as EMP grenades, when they are going against a full-body enhancile. They are... not exactly non-leathal.
• In The Dark Knight Returns the Soviets launch a single nuclear missile at the contested island of Corto Maltese. Superman knocks it off course, but, as Batman points out, this is not a Nuke'Em weapon - the 'Coldbringer' is designed to knock out the enemies' ability to fight, without damaging infrastructure. The weapon detonates, Superman gets almost dead, and the electrics fizzle out in most of the Americas.
• In All Fall Down, the Colony Drop-sized asteroid Penumbra seems to be radiating this, making any missile attack impossible.
• Iron Man has one built into his armor. It disables his own gear as well, which then takes about six minutes to fix itself. The exact same thing is in the War Machine armor.

Fan Works

• In Aeon Natum Engel, among the standard depictions of EMP, it's also one of the main reason for the Iceland's Decade Dissonance.

Film

• The last-resort weapons against the robots in the Matrix trilogy. Big problem there is that they disable your own devices as well. That includes the devices that plug people into the Matrix.
  • Also, in a possible case of Did Not Do the Research, in the Animatrix's The Second Renaissance, it is said that the machines had little to fear from nuclear explosions as they were not affected by the heat and fallout, completely forgetting about the effects described in the page's intro.
• In the 2005 film War of the Worlds the Martians subject urban areas to a terrifying EMP weapon disguised as a lightning storm. It is designed to wreck our technological society before the tripod assault: a instrument of total war.
• In Air Force One a stewardess mentions the titular plane is protected against this, which I suppose is Truth in Television.
• In John Woo's Broken Arrow, a nuke detonated underground produces enough EMP to knock down a helicopter flying above it.
• Speaking of EMP and helicopters, this is the favorite weapon of Blackout in the live-action Transformers film, and I'm pretty sure^{[please verify]} other Transformers have used such weapons, if only mentioned in their Tech Specs.
  • Blaster uses an EMP gun. It blows up normal electronics but Transformers, being more resilient, only suffer from seriously impaired movement coordination (still very painful if you happen to be in jet form at the time).
• In Small Soldiers, the kid blows up a power transformer in the back yard. This generates an EMP that fries the circuitry of all the evil toys. The good toys are shielded by a downed satellite dish, somehow.
• In the remake of Ocean's Eleven, Don Cheadle uses an EMP generator to cause a power outage at the casino so George Clooney and Matt Damon can get past the security lasers. He even describes the device as "a nuke... without the nuke."
  • Assuming that such a device could be built, the rapid restoration of power is a Artistic License Physics/Artistic License Engineering double-header. Not to mention the additional affects that would certainly kill people given the loss of power would also affect anything with an engine and anyone on any kind of life support.
    • Circuit breakers, surge protectors?
      • Not relevant. The pulse works by basically being picked up like a radio wave by any conducting material and converted directly into electricity therein -- and this will happen on both sides of a fuse, breaker or surge protector, because it happens everywhere in all electronics in range, at once. The pulse doesn't politely limit itself to the "inbound" side of electrical connections.
• In The Return Of Godzilla a mild EMP effect was the side effect of prematurely detonating a nuclear weapon launched to kill Godzilla.
• The nuclear bomb in the Made for TV Movie Medusas Child.
• The eponymous Kill Sat in the James Bond movie GoldenEye. And the MacGuffin (though only for the first half of the movie) in A View to a Kill is a computer chip that can withstand EMP, built by Zorn Industries—Bond is investigating how one of these chips ended up in the Soviet Union.
• The "Ion Cannon" in The Empire Strikes Back was a cannon that disabled an entire Star Destroyer without destroying it. "Ion" weapons in future installments of the Expanded Universe (particularly video games) specialize in disrupting machinery.
  • But without permanently shredding the electronics as EMPs do.
    • It's implied in one of the stories (IG-88's section in Tales of the Bounty Hunters) that it does permanently destroy circuity and such, but there are usually ways to auto-repair the damaged paths. Hence the temporary shutdown period, between "destroyed" and "repaired enough to function".
• Shows up in Escape From L.A. as part of a top-secret government project that ends up being stolen by a terrorist who threatens to zap America if the government doesn't meet his demands. The film ends with Snake zapping the entire world instead.
• In Cars 2], Allinol is actually a deadly chemical invented by Miles Axlerod that was designed to catch fire and explode inside a car's engine after being blasted by a deadly electromagnetic cannon that resembles a video camera built by his Dragon, Professor Z.

Literature

• In Harry Turtledove's Worldwar series, the Race begins their assault on Earth by using EMP to disrupt human technology. However, as this is set during World War II, most of humanity's electronics consist of vacuum tubes and are thus unaffected, to the surprise of the invaders.
• In William Gibson's Neuromancer, the US military flight unit "Operation Screaming Fist", led by Colonel Willis Corto (Armitage), is taken down by Russian EMP weapons.
  • In the Neuromancer universe, many companies use Artificial Intelligences to run their computing needs, especially security. Notably, there is a regulatory agency (the Turings) that is aware that A.I. Is a Crapshoot: as such, all AI-equipped supercomputers must be built with an EMP destruct device, triggerable by any Turing agent. As one AI-savvy character puts it, "Every AI ever built has an electromagnetic shotgun wired to its forehead." This is important, as the story revolves around two AIs (Wintermute and Neuromancer) that wish to merge into one superentity - an act that would certainly trigger the EMP bombs.
• EMP (especially handheld EMP) play a key part of Orson Scott Card's Empire series.
• In All Frequency Jamming/Full Band Interception by Chinese Sci-Fi writer Cixin Liu, the future Russian (or Chinese, as it's changed in the Taiwanese version) army saved themselves from the conquer of NATO by using EMP in the most Badass way: first by deploying stationary EMP emitters, then by ramming a giant space station into the sun!
• Carrera's Legions: EMP bombs using conventional explosives to create the pulse are deployed by the Legion several times throughout the series to knock out enemy electronics, particularly their communications.
• In Moon Over Soho the cover story for the Masquerade is that a suspect premises had a miniature EMP bomb in it and not a magical demon trap.
• In Max Barry's Machine Man, love interest Lola's Heart Trauma is mended with a model that discharges an EMP when she gets excited. It does considerable damage and ends up as a Chekhov's Gun.
• In William R. Fortschen's One Second After, an EMP is generated when several nukes are detonated in the atmosphere over the US.
• A key element of the plot of Charles Sheffield's novel Aftermath.

Live-Action TV

• In Stargate Atlantis, an EMP is generated by a Naquadah generator overload and is used to destroy some runaway nanites.
  • Also used in Stargate SG-1 to remotely knock out an alien device through the Stargate (it didn't work).
  • And another was used to disable an enemy command bunker (it worked).
• The BBC's nuclear holocaust drama Threads had an EMP knocking out Britain's electronics before the missiles strike.
• Also in the US Made for TV Movie nuclear holocaust drama The Day After.
• Jericho^[context?]
• An EMP is used to disable the robot angels in the Doctor Who episode "Voyage of the Damned".
  • "Age of Steel", Mrs. Moore uses an EMP bomb to disable a cyberman, who revealed to bride to be. This gives the Doctor a clue on the effects of humans being "upgraded".
• In the first season of Heroes, HRG got Nuclear Ted to emit an EMP instead of his normal nukes in order to shut out the power at Primatech so they could escape.
• In Dark Angel the United States is a third world country because of a terrorist EMP attack.
• In 24 Day 4, a defense contractor deploys an EMP taking out several square blocks of downtown Los Angeles. During Day 8, Samir's terrorists sneak an EMP bomb into CTU New York with an "escaped" hostage to disable the Manhattan radiation sensors.
  • The latter is completely loaded with Fridge Logic. Not only does the EMP take down the entire operations of CTU, but it seems to have been of the plot convenient type, since random devices still work, like flashlights and cell phones (sure, maybe they thought the EMP only affects things which are plugged in, but wouldn't the servers have had UPSes, or at least wouldn't someone have a laptop?). In addition, one has to question exactly how bad CTU security would have been to allow any vehicle within range without first checking it (why not just have the hostage park outside), and why other agencies couldn't just pick up all of the operations that had been dropped by CTU, since when a major terror threat is unfolding, how often is just one agency working on it?
  • Well, Hastings does mention the NSA has brought in a batch of new cell phones. The rest is harder to justify.
    • Solves one issue, raises another: if no one has personal phones anymore (all cells are NSA issued), how is Dana communicating with the terrorists without being noticed?
    • Actually she eventually does get tracked down and caught precisely because they traced the NSA-issued phone to her.
• Leverage features both a handheld version and the much larger bomb version. The handheld version is a much smaller version of the kind that is in development for use in police pursuits. The bomb version actually averts the mistake of Ocean's Eleven, Hardison explains that setting off the device would make them the largest terrorists in American history.
• In the Bugs episode "Pulse", the EMP is referred to as a "pulse bomb", which the protagonists use to escape a heavily armed villain.

Tabletop Games

• Paranoia had the Gauss Gun, a directional EMP weapon useful against robots and other electronic equipment.
• Warhammer 40,000 has EMP grenades as Tau equipment used for dealing with tanks. They rarely see that much use, due to the Tau being the inventors of the railgun—a long-ranged tank killer that makes a lascannon look wimpy.
• GURPS: Ultra-Tech has EMP warheads for properly sized projectiles. Microwave disruptors use a similar technology but are somewhat less effective. Oddly they don't fry the system, instead the effect leaves computers temporarily "unconscious".

Video Games

• City of Heroes has a couple of EMP powers, one of which is delivered via Trick Arrow. It's just described as "a massive pulse of electromagnetic energy", without going into detail how it is formed. They are "powerful enough to affect synaptic brain patterns" (ie temporarily disable all enemy actions, electronic or otherwise), while dealing "high damage to machines and robots". It's a very good power, it just doesn't make much sense outside of Superhero Logic.
• Solidus attempted to EMP New York City in Metal Gear Solid 2.
• Quite a few video games have EMP grenades as weapons. Examples:
  • Fallout
    • New Vegas also adds a "Pulse Gun," an energy weapon implied to be an electromagnetic pulse gun, as it has the same damage bonus vs robots and Powered Armor as EMP grenades.
  • Enemy Territory Quake Wars (considering that your enemy are basically Borg, this works quite well).
  • Battlefield 2142
  • Halo 3
  • Deus Ex features EMP grenades, which are effective against enemy bots. In a twist the protagonist is a cyborg: it's not healthy to get caught in the EMP radius of your own grenades.
    • Human Revolution has them as well, but an upgrade to your augmentations can render you completely immune to their effects. They're also good as distractions against purely human enemies, as they will investigate an EMP explosion as if it were a regular explosion. Important for a Pacifist Run.
  • Project Snowblind naturally includes them and forms the main plot line.
  • In James Bond: Everything or Nothing, EMP grenades are a part of his arsenal.
  • Certain rockets have this as an effect in Armored Core: They temporarily stun the enemy mech.
  • EMP grenades in Transformers: War for Cybertron scramble the HUD and cause static to appear on screen, while leaving movement and weapons operational. They're used by the Scout class.
• Outpost 2^[context?]
• In Banjo-Tooie, Mumbo can use an EMP spell in Grunty Industries to shut down factory machinery.
• StarCraft features an EMP wielding giant spaceship. The EMP knocks out shields, making it only useful against one race, but only REALLY useful against Archons, who have 300 shield and only 10 life.
  • The EMP also eliminates the energy of any units that use energy for abilities, so it can be quite helpful against Terran armies as well.
  • It even works on zerg casters, even though their "energy" is their internal supply of symbiotes and biotoxins. But at least it's consistent.
  • Star Craft 2 features the ability on the Ghost. But on a lower scale, only stripping a certain amount of energy off units.
• Crysis Warhead features EMP grenades that are used to disable the enemy's nanosuits, making them easy kills.
• In System Shock the Magpulser is available. It looks strange, but yes, it harms robots a lot (200% damage). It also lives up to its name by barely affecting cyborgs (50% damage) and not affecting mutants at all (0% damage).
  • There are also a couple of other EMP weapons, specifically the EMP grenade, which, when detonated, can screw up your (computer-assisted) interface if you're too close to the blast. It also drains your battery for some reason. There's a more powerful land mind version as well.
  • Sequel System Shock 2 has the EMP rifle, which absolutely devastates robotic and cybernetic enemies (the cyborgs have all their life-support systems in their mechanical parts, meaning that damaging them will kill them), but is absolutely worthless against a purely biological enemy. Since some of the most powerful enemies in the game are biological, it limits the effectiveness of the gun at specific sections of the game.
• The Dark Forces Saga feature an EMP-shooting gun which is mostly for killing robots.
• Tiberian Sun features an EMP cannon on both factions while its expansion had a mobile EMP tank for GDI. Its more useful against GDI than Nod due to Nod's tendency to use fragile speedsters and that the cannon takes some time to charge and shoot.
  • In Generals, China has an EMP bomb dropped by an airplane. Pretty effective if used with other special abilities to destroy an enemy force or as a starter for an attack on the enemy base. And it looked cool.
  • Tiberium Wars has a tech building that can be captured to grant an EMP attack that temporarily disables enemy buildings.
• In Modern Warfare 2, a nuclear missile is detonated in the upper atmosphere over America, blacking out the eastern states and causing the player to dodge helicopter rain. The player also gets an EMP in multiplayer if they get a Kill Streak of 15, which disables enemy electronics, including removing their radar, ammo count and the game score. It still fails physics forever, of course, because the team that used it is unaffected and the effect only lasts for about two minutes. Modern Warfare 3's Multiplayer introduces EMP grenades that become available at Level 21. The EMP is applied only to players and their electronics caught in the blast radius and the effect lasts for a much shorter period of time.
  • Acceptable Breaks From Reality—who would use the EMP if it affected their own team as well? Nobody. Who would use the EMP if it lasted until the end of the round? Everybody.
• The Space Pirates of Metroid occasionally use EMP grenades. Steam Lords of Elysia can also generate one as an attack. Presumably, Samus' suit is well protected as neither of these actually does anything to her suit beyond standard shield drain. Some special electricity based attacks, however, cause static to appear on the HUD.
• In Ratchet: Deadlocked, your Battle Bots have EMP grenades equipped that allow the temporary deactivation of Stalker Turrets and other electronic obstacles.
• In Command & Conquer Generals, the Superweapon General's base-defense missiles and one of the special powers of high-ranking Chinese generals are EMP-based. These disable vehicles and buildings (albeit, temporarily).
• Splinter Cell: Conviction has a plot focused on detonating several EMP bombs in Washington DC. Sam actually gets a backpack that has a built-in EMP generator fairly early in the game. It can only be used three times per level (no recharging it like other gadgets) and the effect is purely temporary, lasting ten seconds at most. He also has access to EMP grenades, which are even less effective, but ranged.
• In Devil Survivor, it is explained that the PSE law places a chip in all electronics so that they can do this to all of Tokyo in a massive explosion. In fact, that's their if-all-else-fails plan.
• In Need for Speed: Hot Pursuit 2k10, both the police and the racers use EMP devices on each other. In the "Porsche Patrol" cop event, you gain an achievement/trophy by using the EMP weapon to take out the computer-controlled gas/electric 918 Spyder Hybrid concept.
• In Battlefield Bad Company 2 the plot revolves around the members of the Bad Company trying to find a mysterious weapon which turns out to be an EMP.
• Bubble Tanks Tower Defense 1.5 introduces the EMP creep, which explodes into an electromagnetic pulse upon defeat. This disables all the towers around it, and as such makes it an annoying foe to fight.
• Perfect Dark has EMP mines which have to be placed on the computer terminals to disable the security system in the first level. Unfortunately, they don't appear in other levels with security cameras.

Web Animation

• The use of one forms the climax of the Red vs. Blue series "Reconstruction". The characters also spend a lot of time arguing over whether it's pronounced "E-M-P" or "emp", with even the computer warning using the latter pronunciation, making Washington the only one who uses current pronunciation of E.M.P.
  • as seen at 5:50 in this video

Western Animation

• Max Steel has an episode where Roberto builds a handheld, explosion-less EMP projector in a very short timeframe as a method of dealing with super robots gone rogue. This causes a friendly-fire issue, as Max will die if he loses his nanoprobes. which are just as vulnerable to EMP, and the robots immediately start a fight instead of helpfully lining up. One of them even goes for the EMP device when Berto hesitates on account of this, presumably intending to aim it at Max. Max solves the problem by taking it and using it himself, thus putting his body behind the direction of the blast. He still takes enough of the EMP to destroy a large portion of his nanoprobes, and loses consciousness while the survivors cannibalize the dead probes to replicate new ones.
• Transformers Animated: Ratchet has a wrist-mounted "EMP generator" that can focus an electromagnetic pulse into a beam. It can temporarily knock out most Cybertronians, but Ratchet prefers to use it as a surgical tool, and then only rarely. At full power, it can wipe an Autobot's entire memory, which accidentally happened to Arcee during the Great War, hence his reluctance to use it. He and Bumblebee can temporarily knock a flying Decepticon out of the air by combining their normal weapons (electric stingers + magnets).
  • Team Chaar's Blackout, like the movie 'bot who inspired him, can create an electromagnetic shockwave that knocks out nearby machinery...and then bring them back online by doing it again.
• The Teenage Mutant Ninja Turtles (2003) episode "Modern Love" has the turtles whip up an EMP to disable a rampaging Nano.

Web Comics

• Megatokyo Largo uses one as a rickroll.
• Sluggy Freelance:
  • Aylee from had her Involuntary Shapeshifting mutate her into a living EMP generator in response to a nanite infection. It caused problems as she had to routinely run away from the house for fear of accidentally setting off one of Riff's inventions. Or worse, erasing Bun-Bun's Baywatch video tapes!
  • Torg at one point used an EMP bomb to fry Dr. Nofun's lab. That's also how he discovered "Doesn't hurt people!" comes with "...unless some fool stands right next to it, of course".
• An EMP effect was used by the protagonists of Molten Blade to aid their escape from a research facility, generated from a device referred to as an "e-bomb" by one of the characters.
• In the Bob and George comics, during the Mega Man 3 storyline, Mega Man was able to convert the Magnet Missiles into an EMP. It's very effective, but he burns them out after two uses.
• Doctor Mittelmind in Girl Genius has an implanted "pulse cannon" which disabled most hardware in the room, and they're lucky their collars didn't go off.

Prof. Mezzasalma: It killed him, of course, but her gun did blow up.

• • Not to mention The Lion's “roar,” an electromagnetÆtheric pulse-
    • At least the Lion was made to knock out big things (specifically the Castle), and long-term. The next time they did it accidentally, small clanks suddenly began to keel over. Oh, and Agatha's necklace shut down. Oops.
• In Freefall Ecosystems Unlimited uses an EMP generator to erase digital information from used robot parts. It has no effect on post-it notes, though.

Real Life

• Naturally occurring magnetic storms can be quite rough. The strongest known was Carrington Event (1–2 September 1859) induced by solar events, that took out the entire telegraph system in Europe and North America and parts of Australia and Asia. The strongest measured was Quebec Storm (13-14 March 1989), tripped enough of fuses on the grid to leave more than six million people for nine hours. The largest geomagnetic storms of solar origin measured in the latest decades were Halloween Storms (29-31 October 2003) - a big blackout happened in Sweden, though still less than a hour long, and some transformers burned out even in South Africa. Naturally, such things happened before late XIX century too, but that's known only by auroras observed far from the polar regions.
  • If you want to know what could this do now, there's a study done for the insurance industry: Solar storm risk to the North American electric grid. The conclusion is, Carrington level events are expectable once per 100-250 years, Quebec level events once per 35-70 years. Depending on things like soil conductivity in the affected area and just how thoroughly the grid is hardened, damage can vary a lot, but results of a big one can still be comparable to major earthquakes and volcano eruptions.