- "...or witness the birth of Christ!"
- " With that [having mentioned witnessing the birth of Christ], he [Doc] changed the dial to read 12-25-0. / "Of course," he added didactically, "there's so dispute about that date. Some scholars say Christ was born in the year 4 B.C. and somebody made a mistake in what year it was during the Dark Ages. But assuming 12-25-0 is correct, all we'd have to do is find our way to Bethlehem." "
- —From Back to the Future by George Gipe (quote, pages 53 and 54)
0000 was a series of digits typed into the time circuit display by Emmett Brown to illustrate that the time machine could travel back to year zero. Doc referred to the day of Christ's birth, logically enough, as "DEC 25 0000".
As there was no year zero, this was revealed with the 8-passenger DeLorean to be a limitation of the time circuits. If traveling to a year before 1 A.D, the time circuits would always display 0000. However, Gale-Zemeckis coordinates could be used to determine the exact year. Logically, these spatial coordinates would have to be used for years after 9999 A.D. as well.
- October 25: The date displayed on the time circuit display in the 8-passenger DeLorean when traveling further back than 1 A.D. The Gale-Zemeckis coordinates revealed these years as 1000000 B.C. and 64000000 B.C.
- December 25: The date typed into the time circuit display in the DeLorean time machine on the night of its maiden trip. To illustrate how the time machine worked, Doc typed it in to represent the birth of Jesus Christ. As this merely a demonstration of the time circuits, it's likely Doc didn't plot the Gale-Zemeckis coordinates needed for the actual date. Also, as Jesus Christ was born in Bethlehem, it would be impossible for this model of the DeLorean to travel to the exact time and date of Jesus Christ's birth.
Behind the scenes
- The actual date of Jesus' birth is up to debate, but it is not in year 0. It is generally considered to be around 7-2 BC/BCE instead. This range of years, however, would be impossible to reach with the existing time displays, one flaw of its capabilities. Also, there is no year 0 in the BC/AD year system, there was 1 BC, then the next year was 1 AD.
- In the novelization (see Quote above), year zero is displayed on the time circuits as "0" — a single zero, as here.
- Bob Gale has stated in the DVD commentary that it was an example of a joke that nobody else laughed at -- the idea that a scientist that specialized in time travel experiments for the past 30 years would punch in a nonexistent year "DEC 25 0000" to witness the birth of Christ.