In "Star Trek," what exactly are "star dates"?
Star Trek episodes often refer to the "star date." What exactly is a "star date"? How does it equate to our calendar? Or is it merely sitcom disinformation?
Details are for guys who get paid by the hour, sport. Star dates were among hundreds of unexplained terms thrown into Star Trek by scriptwriters whose main objectives were plausibility, a space-poetical ring, and getting done by deadline.
The dates in the original show (1966-69) were of the form 0000.0 and were assigned pretty much at random, the producers merely keeping a list to avoid duplication. The numbers meant nothing at first but eventually it was agreed the units were roughly equivalent to earth days and the decimals were tenths thereof.
In Star Trek: The Next Generation things were more systematic. One production staffer was "keeper of the star dates" and parceled them out to the episode writers to avoid mixups. The numbers were of the form 40000.0, sometimes with two decimal places. The initial 4 was assigned arbitrarily, the second digit referred to the season, and the remaining three usually progressed from low to high over the course of the season. But everybody was still pretty vague on what the numbers meant in the context of the show.
Not that star dates don't have a rationale. Something of the sort would certainly be required on an actual starship. We know from the theory of relativity that time is local, not universal. When a starship approaches the speed of light, time aboard it slows down from the perspective of us here on earth but continues to hum along at the usual rate for the passengers. Trying to use Earth time aboard the Enterprise would require abruptly speeding up the calendar every time Kirk had Scotty pour on the ions. Better to use "ship time," that is, time as measured on the ship's own clocks. Ship date 1000.5 would mean noon (.5) on day 1000, presumably the thousandth day since the launching of the ship. "Ship date" doesn't sound as snappy as "star date," which falsely suggests there is some universal "star time" (although see below), but I suppose we can allow for a little dramatic license.
Trouble is, star dates don't follow this logical scheme. During the original series star dates ranged from 1312.4 to 5943.7 — a span of 4,600 days, or about twelve and a half years. We know from the opening voiceover that the Enterprise was on a five-year mission. This means either that (1) Kirk and friends were running up some serious overtime, (2) there's more to star dates than meets the eye, or (3) nobody in the show gave the matter a moment's thought.
The real answer is obvious, but Bjo Trimble's Star Trek Concordance (1976), written with some input from producer Gene Roddenberry, gamely attempts to account for things by saying star dates are "a function not only of time but of a ship's position in the galaxy and its velocity." How mere mortals could cope with a timekeeping system of such breathtaking complexity is not explained.
Another problem is that several episodes in the original series took place only a star date or two apart, even though they seemingly cram in a lot more than 24 hours' worth of action. For example, "What Little Girls Are Made Of" begins on 2712.4, "Miri" on 2713.5, and "Dagger of the Mind" on 2715.1. The Concordance ventures the explanation that "warp drive distorts time." This suggests two things: first, star time is universal and not local (in fact the current assumption is that star dates are not peculiar to a given ship but are standard throughout the Federation); and second, inertial (e.g., earth) time would pass more slowly than ship's time, the opposite of what Einstein told us actually occurs. Bjo cheerfully concedes this is a little feeble but says it was the best they could do to make the "theory" fit the numbers in the show. I say they should have admitted Kirk was sniffing dilithium crystals while making entries in the log.
One flub left Bjo no choice. The episode "Spock's Brain" starts on 5431.4 but in mid-show the date is inexplicably given as 4351.5. "The horror of having Spock's brain stolen does strange things to his friends' minds," she notes drily. "Among other mistakes, the wrong star date is entered in the log."