Throughout the history of timekeeping, the humble second has had a number of very particular definitions.
In 1956, it was defined as “1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time.” In 1967, it shifted to an atomic standard: “9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.” Todya, perhaps you know it best as “approximately one Mississippi.”
Any of those are plenty good enough for timekeeping in day-to-day life but none are particularly well-suited to the literally split-second math required to precisely coordinate single frames of video in virtual reality where screens can update at a variety of different sub-second speeds. In order to do away with messy, decimal-ridden arithmetic, engineers at Facebook-owned Oculus came up with a new unit of measurement called the “flick” to help clean up the math required to program things for VR.
A flick or “frame tick” is a 1/705600000th of a second, designed so that a second worth of flicks will divide evenly by common screen refresh rates like 24, 25, 30, 48, 50, 60, 90, 100, 120 as well as various fractional versions of those numbers and common audio sampling rates. The result is a very big number, but one that will make the precise math of dealing with single frames at different refresh rates.
As engineer Christopher Horvath explained in October of 2016 when the standard was first created:
Time and technology have a tendency to clash in strange ways. The phenomenon of the leap second, which is designed to control for unpredictable variations in the Earth’s rotation. It’s easy for you or me to imagine adding and an extra second to a particular minute, but much harder for computers which tend to solve the problem by “smearing” time over the course of as long as a day.
Smeared seconds are rare, but flicks probably won’t be. Not only do they solve an annoying problem, but they’re also bundled into an open-source code library in an attempt to standardize their use throughout the industry. It’s only a matter of (a few quintillion) flicks before it catches on.