Land Before Time
The questionable necessity of infinitesimal measurements of time
Glen Gibbons at Folio show, where Inside GNSS won a silver award for editorial
Maybe I should have labeled this little essay, “Land After Time,” because that’s what our technological world has become.
In that wonderful metaphor of our beginnings, the world arrives in the dark without form — no latitude, no longitude. Then light appears, separate from the darkness.
And there’s the genesis of time: alternating intervals of day and night.
That seems to work pretty well for several billion years. Finally, someone — an astronomer, probably, ordained or ad hoc — makes the connection between those intervals and the movement of the Earth, between the seasons and our planet’s relationship to the Sun.
So, timekeeping improves an order of magnitude or more. Next, another someone — a geometrically inclined soul — suggests that, if the Earth is roughly a sphere whose circumference is 360 degrees and its diurnal rotation is 24 hours, then we can assign an equivalence between distance and time. We can measure the spaces between places in arc minutes and arc seconds, in memory of the increments of the day.
But that’s no longer good enough, we learn (if we hadn’t figured it out already) from Michelle Stacey’s lovely reportage in the December issue of Harper’s magazine, “Clash of the Time Lords.” Although subtitled grandly, “Who will own the measure of our days?” the article is really about that infinitesimal, occasional, and unpredictable fluke of human nurture, the leap second, and a controversial proposal to ban it from Coordinated Universal Time (UTC).
For those who missed Dennis McCarthy’s contribution on the subject in our “GNSS Solutions” column last January, it’s all reprised here, only with more journalistic theatrics and a bigger cast. (I was surprised to learn that thing about George Washington’s birthday. Check it out.)
McCarthy, the former director of the Directorate of Time at the U.S. Naval Observatory (USNO), advocates dropping the tics of the leap second, which ties us to the astronomical time (UT1) of the Earth’s rotation, and let cesium do the tocking. And this perspective, remember, is backed up by the dozens of atomic clocks at the Naval Observatory — the biggest contributor to UTC — counting out those 9,192,631,770 cesium oscillations that have defined the second since 1967. (It’s all about hertz, baby, and USNO tries harder.)
As a person who just got around to having his picture taken on the Greenwich Prime Meridian and mulling over John Harrison’s clocks at the former observatory there, I’ll admit it right now — I don’t have a dog in this fight. The Global Positioning System has gotten along without leap seconds for nearly 30 years, and if GPS system time — which drives the phones, the power grids, the Internet, and even more important, the banks — can get along without it, that’s fine by me.
After all, that stuff is not about time itself, but about metrics – more specifically, frequency: creating the most regular, precise, and reliable calibration of time intervals. And this can be done — probably best done, argue the physicists — quite apart from planetary revolution with its tiny eccentricities and eroding velocity.
Maybe I should have labeled this little essay, “Land After Time,” because that’s what our technological world has become. We needed something better than time to keep up with all those inventions of busy human minds: air travel, stock trades, text messaging, the rest of it.
Timing, synchronization, that’s what we needed, not Time with a capital T. That’s more a matter for metaphysics than physics, for our relationship between ourselves and the created world, not the one we are creating.
But if we get outside our own little parochially terrestrial reference frame, I expect that time works much more differently than any offset between UTC and UT1 can account for. That’s why Gravity Probe B — with the help of on-board GPS — aligns itself to the stars to check out Einstein’s theories on relativity, right?
And to bring it back down to the microcosm of day to day, I much prefer an analog watch to digital. A nanosecond may slip by me here or there, maybe even an entire leaping second. But that clock displaying at least half a day, at least 180 degrees of the great circle of life, gives me context within time, the same way that positioning needs a map to orient us in space.
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