Roentgen meter

The roentgen meter showing empty on Marty's arrival in 1955.

"How did I ever expect to get back? One [plutonium] pellet, one trip. I must be out of my mind!"
—Doc, preparing to travel to 2010 but remembering just in time he has forgotten the plutonium case
"His [Marty's] eyes fell on the dashboard readouts once again. One in particular caught his eye. It was located directly below the Plutonium Chamber, a flashing light that blinked EMPTY over and over."
—From Back to the Future by George Gipe (quote, page 76)

The roentgen meter was a meter on board the DeLorean time machine that measured the amount of radiation in roentgens produced by the plutonium powering the flux capacitor.


When the plutonium chamber ran out of fuel, an alarm sounded indicating refueling. This occurred to Marty McFly after he arrived in 1955 without any more plutonium. Dr. Emmett Brown had been about to load the plutonium case into the DeLorean at Twin Pines Mall prior to his planned trip to 2015, but was prevented from doing so by the arrival of the Libyans. Coincidentally, the engine also ceased to run. The roentgen meter was one of the many items that Doc had annotated with Dymo labels.

Behind the scenes[]

  • It is unknown what happened to the roentgen meter. Later on, In some scenes from Back to the Future Part II and Back to the Future Part III, it can be seen with the normal appearance but without the Dymo labels. (After Doc had the DeLorean hover-converted in 2015, he also installed a not exactly "street legal" Mr. Fusion Home Energy Reactor. This meant the roentgen meter became obsolete, as plutonium was no longer necessary to power the time machine.) In Back to the Future: The Game, the roentgen meter in the DeLorean time machine is replaced with a Mr. Fusion meter but since the DeLorean from the game is a temporal duplicate, the meter should have been temporally duplicated and have the same appearance as it does in Part II and Part III. The only explanation is that the meter was changed when the DeLorean was being fixed when the automatic retrieval feature was added in its place.



See also[]