Timekeeping
TLDR: Utopia tracks galactic time separately from time-of-day/year, which is local.
Prerequisites: None, but it’ll be less weird if you know about heximal.
One of the basic roles of civilization is to help people coordinate by providing conventions, reference points, and standards. For instance, the convention of only driving on one side of the road helps people go faster and have fewer accidents. The default orientation of maps being north-is-up helps people read and make sense of directions. And of course, shared notions of timekeeping helps people meet each other at the right times and otherwise coordinate.
The level of precision and care that must be taken in any of these things depends on how many people use them and how important it is to them to get things absolutely right. For two friends it might be sufficient to say “I’ll come over to your place this weekend” and leave it at that. But for some, moments of difference can mean life-or-death. Some scientific instruments can be totally ruined by bad timekeeping. Fortunes can be gained or lost based on milliseconds of difference on a high-speed stock exchange.
Time is, in some ways, harder to measure than many things. Consider measuring the length of something. If you do it wrong the first time, or your measuring tape is defective, you can try again with a better tool. But with time there’s no foolproof way to check how long it’s been since some event unless you get things right on the first try. It’s possible to measure a distance twice and average the results, but we simply can’t go back and measure durations again. Thus we owe it to the future to keep precise logs of when things happen, and to make sure the clocks we use to keep track of the passage of time are functioning correctly.
One might think that timekeeping is as simple as setting up a clock and counting the number of seconds (or some other unit) that pass. Coordinating time would just be a matter of using that clock to agree on when something like a meeting should happen. It would be nice if it were that simple! Three things stand in the way: relativity, malfunction, and competing units.
Relativity
One of the most counterintuitive findings from physics is that the passage of time itself depends on who appears to be moving quickly and who appears to be stationary. Note the word “appears.” There is no ground-truth about how fast an object is moving, and there is thus no ground-truth about how much time has passed.
My favorite example of time dilation seen in real life comes from Minute Physics:
In order to measure the passage of time, we must choose an inertial reference frame — a perspective that isn’t accelerating. This is the resolution to the twin paradox: if a spaceship leaves Earth and travels around the galaxy at close to the speed of light and then comes back, what subjective-age will the traveler be compared to those on Earth? From the perspective of Earth, the traveler has been moving quickly, and as a result has been experiencing less subjective time. But from the traveler’s perspective while in deep space, the Earth is moving relatively quickly and thus experiencing less subjective time. And indeed while coasting in flight, the traveler will see the Earth age slowly. But as the traveler turns around and comes back home, the traveler will see the Earth begin to age extremely rapidly, thus ultimately being younger than those they left behind once they get back.
Is thus vital that whatever perspective is taken when establishing a standard time frame, it should not only have a specific velocity, but that this perspective should not accelerate (or at the very least have a consistent acceleration, so that it can be compensated for later, if needed). These sorts of relativistic effects may seem small at the kinds of speeds that humans experience, but over time they can build up and wreak havoc on precise systems. The Global Positioning System, for example, has to take into account the speed of the satellites in orbit in order to give good results.
Worse, general relativity says that there is a deep connection between accelerating and having weight. Objects at rest on a planet are, in a very real sense, accelerating the same way that objects in orbit would be. As a result, any planetary clock will tick more slowly than it would in deep space.
No current timekeeping standards account for relativity like they should. The best that Earth has is the Barycentric Coordinate Timeframe (TCB), proposed in 1991. TCB takes the perspective of someone who sees the sun as stationary, but is outside of its gravity-well. Thanks to compensating for relativistic effects, TCB clocks count intervals that are shorter than those on Earth; each century that goes by will result in about 49 seconds of divergence.
Malfunction
Clocks are imperfect machines. Even though atomic clocks are some of the most precise machines ever built (the USA’s primary clock, NIST-F2, measures time with an uncertainty of 1 second in 300 million years), they are subject to errors.
To make sure that standard time is well-kept, 450 clocks across the world each track the passage of time. These measurements are then compared, and a weighted average is formed (using prior estimates about which clocks are most accurate). This weighted average is taken to be the true quantity of elapsed time, and almost all of the clocks in the world are set according to it. When your computer connects to the internet, one of the things it does is synchronize its clock with the authority.
This seems like a pretty good system to me. Good job, Earth!
Competing Units
Of course, no discussion of timekeeping would be complete without mentioning leap-units. Because time it takes Earth to go around the sun (a year) is not a clean multiple of the time it takes distant stars to subjectively revolve around us (this is the true definition of a day), we fudge units of time by counting an additional day in February every so often.
This hack is done mostly so that calendar dates (which are based on days) don’t come out-of-sync with times-of-year. We want December 25th to be in winter (for the northern hemisphere!), et cetera. Note that in the absence of leap-days, it’s still totally possible for birthdays (and Christmas) to be celebrated at the same time each year! They’d just need to move calendar-days to reflect the mismatch of days to years. What was celebrated on December 25th one year might be celebrated on the 24th the next, and the 23rd four years after that.
Whether this is a good idea is questionable. But it’s worth noting that, as anyone who was born on February 29th can tell you, leap-day errors and bugs are extremely common. The “logic” of trying to figure out whether February has 29 days is arbitrary in comparison to just multiplying numbers. In a future with civilizations on other worlds, it may cease to make sense to follow an Earth-centric calendar.
Worse than leap-days are leap-seconds. Because the length of the day is not a precise number of seconds, additional seconds are randomly added to (or subtracted from!) our clocks. And I do mean randomly. The Earth’s rotation is chaotically affected by earthquakes, tides, and the gradual movement of tectonic plates. It is genuinely impossible to know how many seconds will have elapsed after another billion days on Earth (assuming nothing crazy happens).
While most people know about leap-days, and can plan around them, few know about leap-seconds, and certainly they can’t be planned around. Computer systems frequently assume that each minute has 60 seconds, and bugs around the occasional 61 seconds in the minute were so common that Google decided to instead smear leap seconds out over the day (making each “second” a tiny bit longer).
Notice that both leap-seconds and leap-days were added for the same reason: to pretend like an arbitrary celestial movement evenly aligns with a clock with different units.
To this, and every other random, inconsistent timekeeping hack, I say we just stop.
Utopian Time
In Utopia there is an explicit distinction between galactic time, and various local phenomena such as noon or solstice. When someone schedules something, they may start with something like “Are you free tonight?”, but they ultimately coordinate using galactic times.
The galactic time standard doesn’t use days or years, which would be naturally biased towards particular planets. Instead, the fundamental unit of time is based on the wavelength of a photon emitted from a low-energy caesium-133 atom, which happens to be particularly convenient in building atomic clocks. Specifically, one standard galactic blink is equal to 6^12 times the amount of time it takes a photon of that wavelength to go through one full oscillation… which is approximately 0.24 seconds.
To make working with this unit easier, a few derivative units exist for talking about longer periods:
36 blinks = 1 breath ≈ 8.5 seconds
36 breaths = 1 rest ≈ 5 minutes
36 rests = 1 visit ≈ 3 hours
And of course, there are non-standard, large units like days and years.
Smaller units of time are usually expressed as how long it takes light to travel some distance. See my essay on distances for more.
The most common unit of time is the rest. A day is about 282 rests. A year is about 103 thousand rests. There is no galactic calendar — simply a choice of a point in time to be zero, around which all times are specified as either positive or negative offsets.
Each place will also have local conventions about relevant periods of time and noteworthy moments during those periods. For instance, planets will have a local notion of days and years, and locations on a planet will have notions of sunrise/set and seasons, depending on time of year. Many places on Earth use a sixths-of-the-day (4 hours) system where the first three periods are before noon and the last three are after noon, but notably this system varies place-to-place and is not intended to be precise or substitute for galactic time.
For instance, let’s say that Alice wants to go on a date with Bob, and they need to pick a time to meet. Since they both live in the same place, they can reference local phenomena, and Alice suggests 12 rests before dusk three days from now. Bob checks his calendar and says that sounds fine. “I’ll see you at ⌊341305” he says, indicating a time by only specifying the digits of galactic time that are on the relevant timescale (rests to ~tens-of-thousands of rests). If the two had been planning a phone-call, Alice might have suggested a time directly, rather than referencing dusk. Regardless, the emphasis on galactic time reduces the risk of falling prey to time zone issues.
Galactic time is calculated by keeping time in a variety of locations, with a variety of methods. Adjustments are then made for the light-speed delay in communicating with the central authority, as well as for gravity and acceleration, including the acceleration due to the solar system orbiting around the center of the galaxy. These measurements are then archived, averaged, and the resulting time is broadcast out to whomever is interested.
P.S. From the perspective of the galactic reference frame, how much of the velocity of someone on Earth’s equator is due to the spinning of the Earth, the orbit of the Earth around Sol, and the orbit of Sol through the galaxy?
Equatorial rotation speed: 0.46 km/s (or 3.9 km/s if you’re a GPS satellite)
Earth orbital speed: 30 km/s
Sol’s orbital speed: 230 km/s
Turns out we’re all going pretty fast! (And our clocks are thus running slow! 🕰️)