DeLorean time machine

Operation

The control of the time machine is the same in all three films. The operator is seated inside the DeLorean (except the first time, when a remote control is used), and turns on the time circuits, activating a unit containing multiple fourteen- and seven-segment displays that show the destination (red), present (green), and last-departed (yellow) dates and times. After entering a target date, the operator accelerates the car to 88 miles per hour (141.6 km/h), which activates the flux capacitor. As it accelerates, several coils around the body glow blue/white while a burst of light appears in front of it. Surrounded by electrical current similar to a Tesla coil, the whole car vanishes in a flash of white/blue light seconds later, leaving a pair of fiery tire tracks. A digital speedometer is attached to the dashboard so that the operator can accurately gauge the car's speed. Various proposals have been brought forth in the past by fans of the movie franchise for why the car has to be moving at 88 mph to achieve temporal displacement, but actually the production crew chose the velocity simply because they liked how it looked on the speedometer.

Observers outside the vehicle see an implosion of plasma as the vehicle disappears, while occupants within the vehicle see a quick flash of light and instantaneously arrive at the target time in the same spatial location (relative to the Earth) as when it departed. In the destination time, immediately before the car's arrival, three large and loud flashes occur at the point from which the car emerges from its time travel. After the trip, the exterior of the DeLorean is extremely cold, and frost forms from atmospheric moisture all over the car's body.

A few technical glitches with the DeLorean hinder time travel for its users. In the first film, the car has starter problems and has a hard time restarting once stopped, much to Marty's repeated frustration. In the second movie, the destination time display malfunctions and shows random dates (mostly January 1, 1885), which partially cause Doc to be sent to 1885. In the third movie, the flying circuits (added by Doc in 2015), fuel line, and fuel injection manifold are damaged, preventing the car from moving under its own power.

Fuel

The time machine is electrical and requires a power input of 1.21 jigowatts (gigawatts) to operate, originally provided by a plutonium-fueled nuclear reactor. In the first movie, Doc has no access to plutonium in 1955, so he outfits the car with a large pole and hook in order to channel the power of a lightning bolt into the flux capacitor and send Marty back to 1985. During Doc's first visit to 2015, he has the machine refitted to hover above ground in addition to standard road driving, and he replaces the nuclear reactor with a Mr. Fusion generator that uses garbage as fuel.

Although the Mr. Fusion unit provides the required power for the time machine, the DeLorean is still powered by an internal combustion engine for propulsion. The fuel line is damaged during Marty's trip to 1885 in Back to the Future Part III; after he and Doc patch it, they attempt to use whiskey as a replacement fuel. The test fails, destroying the car's fuel injection manifold and leaving it unable to travel under its own power.

Doc and Marty consider options to reach the required 88 mph (such as pulling it with horses) but ultimately settle on pushing the car with a steam locomotive. For the extra power needed to push the DeLorean up to speed, Doc adds his own version of "Presto Logs" (a chemically treated mixture of pressed wood and anthracite) to the locomotive's boiler and chooses a location with a straight section of track long enough to achieve 88 mph.

The power required is pronounced in the film as one point twenty-one "jigowatts". While the closed-captioning in home video versions spells the word as it appears in the script, jigowatt, the actual spelling matches the standard prefix and the term for power of "one billion watts": gigawatt. Although rarely used, the "j" sound at the beginning of the SI prefix "giga-" is an acceptable pronunciation for "gigawatt." In the DVD commentary for Back to the Future, Bob Gale states that he had thought it was pronounced this way because it was how a scientific adviser for the film pronounced it.

Flux capacitor

The flux capacitor, which consists of a rectangular-shaped compartment with three flashing Geissler-style tubes arranged in a "Y" configuration, is described by Doc as "what makes time travel possible." The device is the core component of the time machine.

As the time machine nears 88 mph, light coming from the flux capacitor begins pulsing more rapidly until it becomes a steady stream. Doc originally conceived the idea for the flux capacitor on November 5, 1955, when he slipped while hanging a clock in his bathroom and hit his head on the sink. A similar, but more primitive, steam-powered flux capacitor is also seen in the chimney headlamp of Doc's second time machine, the Time Train, at the end of Back to the Future Part III.

Although the films do not describe exactly how the flux capacitor works, Doc mentions at one point that the stainless steel body of the DeLorean has a direct and influential effect on the "flux dispersal", but he is interrupted before he can finish the explanation. The flux capacitor requires 1.21 gigawatts of electrical power to operate, which is roughly equivalent to the power produced by 15 regular jet engines.

The instruction manual for the AMT/ERTL DeLorean model kit says: "Because the car's stainless steel body improves the flux dispersal generated by the flux capacitor, and this in turn allows the vehicle smooth passage through the space time continuum."

Mr. Fusion

The Mr. Fusion Home Energy Reactor is the name of a power source used by the DeLorean time machine in the Back to the Future trilogy. It can be seen for the first time at the end of Back to the Future when "Doc" Emmett Brown pulls into the McFlys' driveway after a trip to the year 2015. It is a parody of Mr. Coffee machines, which were very popular at the time of filming. The appliance from which the prop was made was actually a Krups "Coffina" model coffee grinder.

The Mr. Fusion Home Energy Reactor converts household waste to power for the time machine's flux capacitor and time circuits using nuclear fusion, presumably cold fusion. In the film, Mr. Fusion allows the DeLorean time machine to generate the required 1.21 gigawatts needed to travel to any point in time. The energy produced by Mr. Fusion replaces plutonium as the primary power source of the DeLorean's time travel, allowing the characters to bypass the arduous power-generation requirements upon which the plot of the first film hinges. The plutonium fission reactor was most likely left installed underneath Mr. Fusion as a backup power source.

The Mr. Fusion can provide enough power to the flux capacitor but is not used to power up the DeLorean itself, which makes use of an ordinary gasoline combustion engine to reach the 88 mph speed necessary for it to time travel, a limitation that proved itself crucial in the third movie when Doc and Marty find themselves stuck in 1885 and unable to return with the DeLorean out of gas (due to a fuel leak). The vehicle's hover system is powered by Mr. Fusion and is capable of bringing the DeLorean up to the required 88 mph; the combustion engine was also probably left on board as a backup. However, the flight systems were destroyed as a result of a lightning strike, leaving Marty to rely on the original combustion engine, which in turn was disabled.

Fictional timeline

For most of the first film, the 1.21 gigawatts are supplied by a plutonium-powered nuclear fission reactor and, with the absence of plutonium, a bolt of lightning channeled directly into the flux capacitor by a long pole and hook in the film's climactic sequence. At the end of the first film, and for the remainder of the trilogy, the plutonium nuclear reactor is replaced by a "Mr. Fusion Home Energy Reactor" generator possibly acquired in 2015. The "Mr. Fusion" device apparently converts household waste into electrical power; the name suggests nuclear fusion. Due to a "hover conversion" made in 2015, the car also becomes capable of hovering and flight, though it lost this ability at the end of the second film.

The DeLorean returns to 1985 and proceeds to travel to October 21, 2015, to stop Marty's future son from committing a crime. While there, the DeLorean is stolen by Biff who then travels back to November 12, 1955, the same day as the climax of the first film, to give his past self a sports almanac to be used for gambling. Once Biff returns to 2015 without Doc's knowledge, the duo return to 1985, but find themselves in an alternate timeline where Hill Valley is ruled by Biff that Doc described as 1985A (alternate 1985). The DeLorean then travels back to 1955 to restore the timeline, but in the aftermath, it is struck by lightning again in the very same electrical storm, this time by accident. According to writers Bob Gale and Robert Zemeckis, the lightning causes the DeLorean to spin at 88 miles per hour, and Doc later states in a letter to Marty that the bolt caused a "gigawatt overload" which "shorted out the time circuits and destroyed the flying circuits". The DeLorean then disappears from 1955, travelling back in time to January 1, 1885 (earlier in the film, Doc mentions that the time circuits are not functioning correctly; several instances in the film that show the time circuit display showed 1885 as the destination when the time circuits malfunctioned).

Once in 1885, the DeLorean is hidden in a mine because suitable replacement parts to replace its destroyed microchip will not be invented until 1947 (presumably referring to the transistor, invented in that year). Doc and Marty recover the DeLorean from the mine in 1955, and Doc builds a vacuum tube circuit assembly to replace the destroyed microchip circuitry and restore the vehicle's time travel capabilities. The tires have disintegrated in storage, so Doc replaces them with whitewalls. The gasoline engine is still functional, but the flying circuits are not.

In a letter Doc wrote to Marty in 1885, Doc states he is happy in his new life there and requests that Marty not attempt to retrieve him, but instead to return to 1985 and destroy the DeLorean, believing that it has brought them and the world nothing but disaster. However, Marty and the Doc of 1955 learn of tragedy to come Doc's way when he is murdered by Biff's grandfather, Buford "Mad Dog" Tannen, on September 7, 1885; therefore, 1955 Doc agrees to send Marty back to the Old West to rescue himself.

When Marty arrives in 1885, the DeLorean's fuel line is pierced by an arrow during an Indian attack. He and Doc patch it and attempt to use whiskey as a replacement fuel, since commercial gasoline is not yet available; the test fails, destroying the fuel injection and ignition systems and leaving the car unable to travel under its own power. Its final trip, from 1885 to 1985, is propelled by a steam locomotive that has Doc's version of "Presto Logs" (pressed wood treated with anthracite) added to the boiler to provide the extra power needed to push the car up to 88 mph; once this speed is reached, the Mr. Fusion unit provides the power required to activate the flux capacitor and make the jump through time. Doc replaces the 1955-style wheels with cast iron train wheels that fit on the track rails. He uses the old tires and a wooden support to cushion the locomotive's "cow catcher" and the car's rear end. Since each of the three "Presto Logs" fire at different intervals with increasing power, Doc installs a boiler temperature gauge on the DeLorean's dashboard to indicate when the car will experience a sudden burst of acceleration.

Once the DeLorean makes its final trip from 1885, it arrives back in 1985 and is immediately destroyed by an oncoming freight train running in the opposite direction. Marty is able to bail out of the car seconds before the train strikes. Later the Time Train, which is Doc's second time machine, appeared in the same spot where the DeLorean was destroyed.

Other elements

In the films, the DeLorean time machine is a licensed, registered vehicle in the state of California, where the films take place. The vanity license plate used in the film reads "OUTATIME", a deliberate anomaly, as the maximum number of symbols on California plates is seven characters. When Doc returns from 2015, it is a barcode license plate, which implies that by that year license plates have moved to other more sophisticated means of tracking and registering.

In The Animated Series, Doc builds another DeLorean into a time machine, restoring most of its features, including Mr. Fusion and the hover conversion (Doc either rebuilds the one destroyed at the end of Part III or he simply builds a new one). He also seemingly adds the capability to travel through space in addition to time (i.e., appear at a different location from the one it departed), similar to the TARDIS from Doctor Who. The cartoon DeLorean time machine has many add-ons, including a back seat in normal two-door mode, the ability to transform into a four-door, a pop-out covered wagon top, a blimp, a rear video screen, and a voice activated time input.

Back to the Future: The Game features a chronal duplicate of the original DeLorean, which Doc Brown recovered from the timestream after the destruction of the original. This DeLorean is created at the end of Back to the Future Part II, when the original time machine was struck by lightning: while the DeLorean itself is sent to 1885, a fully functional duplicate appears (apparently unmanned and undamaged) in 2025, where Doc retrieves it with the Hover Train. He later traveled to 1931 and sent the DeLorean to 1986 to get Marty to rescue him from 1931 before he can be killed. This duplicate DeLorean is effectively the same as the Part II car, including the occasional glitches in the time controls (mostly effecting the last time departed time display), but with a new automatic retrieval feature that automatically brings the DeLorean to a set time and location of Doc's choosing every time Doc Brown doesn't return to the car in a fixed amount of time.

This DeLorean is later badly damaged (Marty crashes the DeLorean into a billboard, and after Marty gets out, the DeLorean falls through the billboard and crashes onto the ground) and then restored by an alternate version of Doc Brown who has never developed time travel technology, having access to limited notes about the flux capacitor. As such, the chronal circuits of the duplicate DeLorean become even more glitchy, accumulating errors as severe as the interval of time traveled, with increasing damage with every attempt: as such, Citizen Brown, the Alternate Doc, has to install a diagnostic console made of materials available in 1931 (appearing as a plywood box with a lightbulb and several similar bulbs placed on the coils on the outer body).

Apparently, part of the problem is chromium parts becoming unstable during time travel, according to Alternate Doc. This DeLorean is then stolen by Edna Strickland, one of the game's main villains. The more adept Doc Brown returns in another duplicate DeLorean due to earlier events in the game, although it is unknown where it came from. Then Officer Danny Parker nearly arrests Marty and Doc for allegedly having the car that Edna got away in. After they explain to him that there is more than one DeLorean, Marty explains that the other DeLorean had malfunctioning time circuits. To make matters worse, the entire town of Hill Valley disappears around them. They go to "Mary Pickford's" house and see that the other DeLorean had been destroyed. After they get information from Mary, who was really Edna, they go to 1876. After they stop the fire that would've burned down Hill Valley, they chase down Edna, who is trying to get away in the first DeLorean. Marty synchronizes the two DeLoreans and hoverboards back to Doc's DeLorean, which is flying behind the one Edna's driving. They all travel back to 1931, with Edna's DeLorean duplicate vanishing because of the time ripples catching up with them, causing "chronal decay" (i.e., since the Alternate Doc timeline ceased to exist, the alternated Clone DeLorean was folded back with the real Clone DeLorean).

It is implied that the Hover Train stays with Clara, Jules and Verne, passingly mentioned as enjoying the same nomadic life around the time-stream of Doc, but it is never seen in the game. The ending introduces a blue DeLorean and a black DeLorean, but it is unknown how these time machines were created.

In Back to the Future: The Ride, Doc, who now lives in a lab, had created an 8-passenger DeLorean that can fly just like the original DeLorean (which can be seen in the ride and in the outside display) and the Hover Train (which can only be seen in display outside of the attraction). Unlike the original DeLorean, the flux capacitor is in the front of the cockpit along with a small screen, the time circuits, and the speedometer. The original DeLorean is also shown to have its original "OUTATIME" license plate instead of the bar code license plate, but it could just mean that this DeLorean is actually a new one being built into a time machine. However, in a post-credits scene, Clara Clayton, who has built Hover Train with Doc, currently repaired the DeLorean and travels back to 1947 to a farm.

In Doc Brown Saves the World, there was a repaired DeLorean time machine which included new replacement parts from 2015. The DeLorean is also seen in a video promoting Doc Brown Saves the World, and it is unknown as to whether or not a flux capacitor was inside.

Development

The time machine went through several variations during production of the first film, Back to the Future. In the first draft of the screenplay, the time machine was a laser device that was housed in a room. At the end of the first draft the device was attached to a refrigerator and taken to an atomic bomb test site. Director Robert Zemeckis said in an interview that the idea was scrapped because he did not want children to start climbing into refrigerators and getting trapped inside. In the third draft of the film the time machine was a car, as Zemeckis reasoned that if you were going to make a time machine, you would want it to be mobile. The specific choice of vehicle was a DeLorean DMC-12 for the purposes of it looking like an alien spaceship due to its characteristic gullwing doors. However, in order to send Marty back to the future, the vehicle had to drive into a nuclear test site. Ultimately this concept was considered too expensive to film, so the power source was changed to lightning.

When the filmmakers arrived at the point where the time machine would be built into a car, the art department was instructed to come up with designs for the DeLorean. Andrew Probert was the first artist to explore the subject (before Ron Cobb joined the production), but his designs were deemed "too perfect" for the look the producers wanted, which was to make it look as if it had been built in a garage by Doc Brown. The idea was that it had been constructed with parts found in a hardware and electronics store, so it couldn't look too sophisticated. It also had to look dangerous, as Producer Bob Gale noted in the DVD commentary for Back to the Future. The task was undertaken by Ron Cobb who added the coils to the back of the vehicle. The nuclear reactor was also a design choice made by Cobb. This choice proved to be important, given the direction the script had taken. Cobb complemented the nuclear reactor with one vent on the back of the car, since it was generally known at the time that nuclear reactors had vents. Once Cobb had left the production, the producers wanted to balance the design with another vent, keeping a symmetrical aesthetic. Probert was asked to step in and he brought the design to its final form. At the end of the first film of the trilogy these vents become the propulsion system for the improved DeLorean, which now had hovering abilities and could reach the time-traveling speed of 88 miles per hour flying. The production design team added other buttons and lights inside the car to make it look more appealing and complex in order for the audience to have something attractive to look at.

Different parts from three 1981 DeLoreans were used in the first film. Liquid nitrogen was poured onto the car for scenes after it had travelled through time to give the impression that it was cold. The base for the nuclear reactor was made from the hubcap from a Dodge Polara. Aircraft parts and blinking lights were added for effect. In one of the first scenes, carbon dioxide extinguishers were hidden inside the DeLorean to simulate the exhaust effect. Ultimately, five real DeLoreans were used in the filming of the trilogy, plus one "process" car built for interior shots. In the off-road scenes in the third film, a modified-for-off-road VW Beetle frame was fitted to the DeLorean with the whitewall tires and baby moon hubcaps. A seventh DeLorean was also used in the filming; however, this one was merely a full-sized, fiberglass model used for exterior shots where the vehicle hovers above the set as well as when the actors interact with the vehicle.

Rather than use the sound of the stock V-6 DeLorean engine in the film, the sound of a V-8 from a Porsche 928 was used.

Replicas

A number of private auto customizers have built replicas of the DeLorean time machine. Starting with a stock DMC-12, they added most, if not all, the props used by the movie producers for the picture cars. In addition to the interior and exterior props, they feature working indicator lights and switches along with the actual sounds which duplicate the ones made by the movie car's controls when activated. These vehicles are, for the most part, roadworthy DeLoreans with stock drivetrains, and are frequently driven to car shows and Back to the Future-related events.

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