The flux capacitor is the fictional core component of Doctor Emmett Brown's time traveling De Lorean DMC-12 in the 1985 movie Back to the Future, its two sequels, and the animated series. Brown states that the flux capacitor "is what makes time travel possible."
The term flux capacitor has become commonly used slang or buzz word for a device whose operation might be too complicated to briefly explain, especially if it fails to operate properly, as in "The file server went down due to a flux capacitor problem."
How it "works"
It is not made clear in the movie exactly how the flux capacitor works. It consists of a box with three small, flashing incandescent lamps arranged as a "Y", located above and behind the passenger's seat of the time machine. As the car nears 88 miles per hour, the light of the flux capacitor pulses faster until it has a steady stream of light. The stainless steel body of the DeLorean also has a beneficial effect on the "flux dispersal" as the capacitor activates, although Doc is interrupted before he can finish explaining it fully.
At the end of the third film in the series, when Doc Brown has converted a locomotive into a time machine, the flux capacitor is located on the front of the train, in place of the lamp.
On November 5 1955, Doctor Emmett Brown came up with the idea of the flux capacitor after slipping and bumping his head while standing on his toilet to hang a clock. The idea came to him in a vision he had after being knocked out.
In order to travel through time, the vehicle integrated with the flux capacitor needs to be travelling at 88 mph (141.6 km/h), and requires 1.21 gigawatts of power (1 210 000 000 watts), originally supplied by a plutonium-powered nuclear reactor. However, for the time machine's return trip (from 1955 back to 1985), plutonium was not available, so a lightning rod was connected directly to the flux capacitor and was used while the vehicle sustained 88 mph. Plutonium was used once again for a trip forward in time at least 30 years, and at some point thereafter the plutonium reactor was replaced by a "Mr. Fusion" home energy generator from the future that was fueled by extracting hydrogen atoms from garbage.
The DeLorean once again came back to 1985 and proceeded to travel to 2015, where it was stolen and taken back to 1955 and returned back to 2015 without the Doc's knowledge. When they returned in 1985, they found it was a different present, so they traveled back to 1955 to fix the timeline. The DeLorean was again struck by lightning in the year 1955, this time by accident. The lightning created an overload and destroyed the time circuits, if you watch closely you will see that the 1885 date was already displayed before the lightning hit, after the LED read-outs flashed, this is a reference to earlier in the film when Doc exclaims that he needs to fix them (they also flash a random date before he hits it and they are corrected), contrary to popular belief the 1885 date was not caused by the lightning hitting the DeLorean. It was then hidden in the Delgado mine for 70 years, "... because suitable replacement parts will not be invented until 1947." This is presumably a reference to the invention of the transistor. It was recovered from the mine in 1955 and repaired by Doc Brown's 1955 counterpart, thus restoring it to working order. Since both gasoline and garbage were available, the next trip back to 1885 was performed under the car's own power.
Due to a broken fuel line, the DeLorean's final trip from 1885 to 1985 was partially powered by a steam locomotive pushing the vehicle up to 88 mph while using Mr. Fusion to generate the 1.21 gigawatts required to activate the Flux Capacitor and break the Time barrier. At the very end of the third movie, Doc returns to 1985 in a time machine made from a train. This uses a flux capacitor that Doc was able to power using steam.
In the movie, the power required is pronounced "one point twenty-one jigawatts". This pronunciation of "gigawatt" is correct (as derived from its SI unit prefix giga); in fact many amateur radio operators from that timeframe correctly pronounced "giga" as "jiga". However, this is more commonly pronounced with two hard "g" sounds as in "golf."
But while "jigawatt" is a correct pronunciation, it is an incorrect spelling (Robert Zemeckis and Bob Gale were unfamiliar with the term and misspelled it in the script). Because of this, a "jigawatt" is sometimes referred to on Internet forums as a fictional unit or to make fun of someone's electrical knowledge. The spelling "jigawatt" is used in the novelizations of films 2 and 3. However, the book of the original film uses the correct spelling "gigawatt".
The Mr. Fusion Home Energy Reactor is the name of a fictional power source used by the DeLorean time machine in the Back to the Future trilogy. It can be seen towards the end of Back to the Future when "Doc" Emmett Brown pulls into the McFlys' driveway after a trip to the year 2015.
The Mr. Fusion Home Energy Reactor converts household waste to power the time machine's flux capacitor and time circuits using nuclear fusion. (It is thought that this is cold fusion.) In the film, Mr. Fusion allows the DeLorean time machine to generate the required 1.21 gigawatts to travel through the space-time continuum. The energy produced by Mr. Fusion replaces plutonium as the primary power source of the DeLorean's time travel and flight capabilities.
When the DeLorean is parked in an alleyway in 2015, a "Fusion Industries" machine is briefly seen.
The phrase "flux capacitor" has appeared in more serious contexts. U.S. Patent 6,084,285 describes a "lateral flux capacitor having fractal-shaped perimeters." The idea being to make a capacitor in an integrated circuit, some of whose capacitance exists between two conductors on a single layer (hence, "lateral"). The device is not a lateral flux-capacitor but a lateral-flux capacitor.
Flux is commonly used in electronics and electromagnetic theory and application, but rarely in the context of a capacitor. In general terms, flux simply means the rate at which some quantity (such as electric charge) passes through a surface (e.g. charge flux). It is speculated that the movie terminology is used fictitiously to represent a new and unknown type of flux.
- The Spanish (Spain only) dubbing of the film mistranslated flux as the inexistent fluzo instead of flujo, adding to the exoticness of a condensador de fluzo. However the Latin American version doesn't have this issue.
- The Italian dubbing of the film mistranslated the name as "flusso canalizzatore", which roughly means "channeling flux"; however, when Marty reads the letter from Doc in the third movie, it talks about the broken "condensatore di flusso", which is an exact translation of "flux capacitor", but at this point appears to be totally unrelated to the rest of the movies (at least for only-Italian-speaking people).
- In the German-dubbed version, the device was once again mistranslated and called the "Fluxkompensator" ("Flux compensator"). The correct German translation for the word capacitor, however, would be "Kondensator".
- In the French version, the DeLorean needs 2.21 gigawatts instead of 1.21.
References in Popular Culture
- The Flux Capacitor is the name given to the finishing move of pro-wrestler Frankie Kazarian.
- Flux Capacitor is a fully improvised comedy show at the Upright Citizens Brigade Theatre in New York City that explores the same window of time from many different angles. 
References in video games
- The Simpsons character Professor Frink can be heard to exclaim "I broke my flux capacitor!" in the video game Simpsons Road Rage.
- The flux capacitor was an electrical slot tech in the turn-based space empire game Stars! The function however, is to increase beam weapon damage by 20%, nothing like in Back to the Future, although the image of it maintains a glowing Y-shape.
- Similarly, a piece of ship equipment in the online space empire game Star Sonata is called the Flux Capacitor.
- In Oni (computer game), the yield of an explosive device contained within a self-destruct system is noted as "1.21 Gigawatts"- the same value required by the flux capacitor in order to work.
- Similarly, in a cutscene in Conflict: Freespace a prototype energy shield is being tested in a laboratory, and one engineer notes that the power delivered to it is 1.21GW. He states the digits separately so it is less immediately identifiable with the phrase spoken in the films.
References in Computing
- The FireWire icon visually resembles the Flux Capacitor.
- On De Lorean's official website:
- A search for a part named "flux" will yield a result of "Flux Capacitor, Part number 18851985".
- A search of a part named "fusion" or "Mr. Fusion" will yield a result of "Mr. Fusion Home Energy Reactor, Part number 19852015A".
- A search of a part named "hover" will yield a result of "Hover Conversion, Part number 19852015".
References in music
- Viktor Vaughn, in the song "A Dead Mouse" from the album Vaudeville Villain, says "I'm outta here soon as I fix the flux capacitor."
- A play on the term flux capacitor was used by the electronic musician A_Scissors when naming his debut album Flux Decapitator, which was released on Polyvibe Records. The first track references the Back to the Future films as it is named "There's a Delorean Flying Over the Winn Dixie".
- The term "flux capacitor" was used in Busted's single Year 3000, in conjunction with the lyrics "he built a time machine, like one in a film I'd seen, yeah".
- Electronic artist remixed an instrumental by musician Harry Grillo titled 1.21 Jigawatts.
References in other movies and television
- Originally labelled the "Oscillation Overthruster" when it was first created and filmed for The Adventures of Buckaroo Bonzai. 
- In the Stargate Atlantis Season One episode "Before I Sleep", Dr. Rodney McKay responds irritably when Maj. John Sheppard mentions the De Lorean in a discussion about time-travel, but doesn't bother to correct him when Sheppard calls the time-travel component of a modified puddle jumper the flux capacitor.
- In the Stargate SG-1 Season Ten episode "200", when Carter reels off a string of technobabble explaining why the Gate is malfunctioning, Martin Lloyd mishears "capacitors" as "flux capacitor."
- In Lois and Clark: The New Adventures of Superman, a flux capacitor is mentioned by H.G. Wells when repairing his time machine.
- Referenced in the "Mind over Murder" episode of Family Guy in which Stewie builds a time machine. When someone finds his drawings they recognize the time machine by noting "this is where the flux capacitor goes".
- The term "flux capacitor" was used in an episode of Star Trek: The Next Generation as being part of an anti-gravity machinery. In the Star Trek: Voyager episode "Prototype", B'Elanna states "I'm going to try to adjust the flux capacitance." See also: Flux capacitor article at Memory Alpha, a Star Trek wiki.
- In an episode of 'Malcolm in the Middle', Hal cashes in his life insurance policy to spend at Vegas and tells Lois he got a bonus from work for an idea to outsource flux capacitors, saving the boss a lot of money.
- In the The Fairly OddParents in the episode Moooving Day, Timmy gets on a Segway, he turns it on and it displays stuff on a screen. The last thing it shows before he moves is Flux Capacitor with a graph under it.
- In an episode of Mighty Ducks cartoon series titled "Bringing Down Baby", the Saurians are plotting to build a weapon that will attract meteors from outerspace to crash down upon the city. The main component that powers the device is the flux capacitor which is mentioned many times throughout the episode by various characters.
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