Flux Capacitor

Lore & Background

During the development of the franchise's narrative, the creative team faced a naming challenge for this crucial device. Initially, it was referred to as the "Temporal Field Capacitor," but director Robert Zemeckis found the name unbelievable. Michael Fink, drawing on his experience with neutron flux from the 1979 drama *The China Syndrome*, and Zemeckis simultaneously proposed renaming it the "Flux Capacitor." This change stuck. Artist Ron Cobb and illustrator Andrew Probert had already conceptualized placing the device on both the external and interior roof of the DeLorean before Fink intervened. Fink ultimately positioned the unit next to the driver's seat for practical filming needs. To build a functional prop, Fink constructed the device using a NEMA box and backlit Torr High-Voltage relays. The time display was assembled from LMB boxes. When Fink departed the project, he recommended Michael Scheffe as his replacement. Scheffe not only finished the Flux Capacitor build but also constructed the "Mr. Fusion" replacement power supply using parts from a Krups coffee grinder. This iterative design process ensured the component looked "fixed together from common parts," aligning with Doc Brown's eccentric garage-building aesthetic.

In Their Own Story

The visual representation of time travel was heavily influenced by Zemeckis's desire for a violent transition, which he described as a "Neanderthal sitting on the hood of the DeLorean and chipping away the fabric of time in front of him." While animators struggled with how to depict the reverse side of a crack opening in time, they experimented with various effects. An electrical effect enveloping the car was discarded because it mirrored the process used in *The Terminator* (1984). Other rejected ideas included a wave of energy exploding to open a hole or a "cubist" effect where the car broke into segments. Ultimately, animator Takahashi developed artwork showing segments popping out and glowing. Although Zemeckis disliked this specific idea, he opted to use all the animated effects Takahashi drew, including contrails and flashing lights. These were drawn in black and white and optically manipulated to create an explosion that opens the "time slice." This was combined with practical elements like smoke, sparks, flash-bulbs, and tire fire. The actual movement of the car through the time slice was so quick as to be imperceptible, a choice Zemeckis preferred so the audience would not overthink the mechanics.

Reader's Guide

To operate the Flux Capacitor effectively, one must adhere to strict physical parameters. First, the DeLorean must accelerate until it reaches exactly 88 miles per hour (142 km/h). This specific speed was chosen because it is easy to remember and looks "cool" on the speedometer. A custom speedometer had to be built for filming because a 1979 law passed by President Jimmy Carter limited production speedometers to 85 mph. Second, the system requires a massive power input of 1.21 gigawatts. In early concepts, this energy was derived from a nuclear bomb test or plutonium. During the actual filming of the first movie, the location and power source were changed to lightning striking a clock tower in Hill Valley due to budget constraints. The visual signature is defined by blue light; for scenes depicting travel through time, liquid nitrogen was poured onto the car to simulate extreme cold. The device's placement next to the driver allows immediate engagement once the speed threshold is met, initiating the "time slice" effect.

Did You Know?

• The device was originally named the "Temporal Field Capacitor" before Michael Fink and Robert Zemeckis simultaneously suggested changing it to "Flux Capacitor."
• A custom speedometer was built for filming because a 1979 law restricted production car speedometers to a maximum of 85 mph.
• Michael Scheffe constructed the "Mr. Fusion" replacement power supply using parts from a Krups coffee grinder.
• The physical prop was built by Michael Fink using a NEMA box and backlit Torr High-Voltage relays.
• Liquid nitrogen was poured onto the DeLorean during filming to create the visual impression of extreme cold after time travel.