Michael Benson is an American journalist, filmmaker, and self-described "deskbound cosmic pilgrim" with unusually wide-ranging interests.  --  Benson has lived in ex-Yugoslavia and Slovenia since the early 1980s, specializing in describing territory where art, politics, and science meet.  --  Among his accomplishments:  making an award-winning feature-length documentary film "Predictions of Fire" about the multimedia collective art movement NSK and the history of Slovenia and Yugoslavia, filming the first theatrical performance ever conducted before an audience in zero gravity, and writing Beyond: Visions of the Interplanetary Probes (Abrams, 2003).  --  In an op-ed piece in Saturday's New York Times, Benson called attention to a momentous decision that representatives of humanity will make next week:  "whether we as a civilization, for the first time in history, decide to uncouple our time-keeping from the rotation of the Earth."[1]  --  The problem arises because for various reasons the earth's rotation is slowing down "about two milliseconds per day per century."  --  At present "astronomical time" (based on the earth's rotation, and defining a second as 1/86,400th of a day) is regularly synchronized with International Atomic Time (defining a second as "9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom") by adding a leap second every year or two, usually as "the 61st second of the last minute of June or December," Benson reports. "They're used whenever the disparity between atomic time and astronomical time reaches 0.9 of a second."  --  Now the Bush administration, the crew currently at the helm of the U.S. national security state, would like to abandon the leap second, because, it says, "the prospect of future catastrophic errors" may be caused by the leap second.  Modern technologies, including commercial transportation systems, rely on American global position system (G.P.S.) satellites, which use International Atomic Time."  --  (Although Benson doesn't mention it, we believe the delivery systems of American nuclear weapons do, too.)  --  Nevertheless, Benson believes abandoning the leap second, and thus the link between astronomical time and International Atomic Time, would be a mistake.  --  There are practical reasons to retain leap seconds, but for Benson the deepest reason is symbolic: he believes "that our corporeal selves are tied to the Earth."  --  In September, the Scotsman said that the impetus for unlinking time from the earth is coming not from the Bush administration but from "American corporations."[2] ...


Op-Ed Contributor

By Michael Benson

New York Times
November 5, 2005
Page A29


LJUBLJANA, SLOVENIA -- Sometime between the opening seconds of Tuesday and the closing ones of Friday in Geneva, the world's greatest watch-making center, a decision will be made that has profound consequences for our way of telling time. What's in question is the fate of the leap second.

The leap second may seem insignificant -- a chip off a leap year's block -- which is why it has been left in the hands of the bureaucrats at the International Telecommunications Union, the organization in charge of broadcasting international time signals. But what's really at stake is whether we as a civilization, for the first time in history, decide to uncouple our time-keeping from the rotation of the Earth. That would be, to my mind, a serious mistake.

So what is a leap second? It is one way to reconcile the disparity between two very different time-keeping systems. One is International Atomic Time -- or as it is abbreviated by timekeepers, T.A.I. -- which is calculated by measuring the frenetic vibrations of cesium atoms; it is said to be accurate to within one second every 70,000 years. The other has been in force since before history was recorded: astronomical time. It's entirely subservient to the Earth's rotation. We now call it Universal Time 1, or U.T.1.

The macrocosmic, astronomical, U.T.1 definition of a second is that it's one-86,400th of an Earth day. The microcosmic, atomic, T.A.I. definition of a second is that it's "9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom." Put that in your clock and wind it.

Leap seconds allow civil timekeeping to benefit from the precision of atomic clocks while also reflecting the reality of a turning Earth. They're necessary in the first place because the Earth's molten core rumbles and sloshes, which creates a variable spin rate. Meanwhile, the gravitational pull of both the Moon and Sun, interacting with the water that covers 70 percent of our misnamed planet, gradually slows the Earth down as the eons pass. Radio interferometry reveals that the planet's spin is slowing by about two milliseconds per day per century.

The first leap second was in 1972, five years after global time-keeping was definitively transferred to a collective aggregate metronome of what are now around 200 atomic clocks worldwide, and there have been 21 leap seconds since. They're typically the 61st second of the last minute of June or December. They're used whenever the disparity between atomic time and astronomical time reaches 0.9 of a second. Our current time-keeping regimen, based on atomic clocks (T.A.I.) but adjusted to the Earth's rotation (U.T.1) using the occasional leap second, is called Coordinated Universal Time (U.T.C). Anyone interested in precision timing had better get used to abbreviations.

So why is the leap second in danger of being dragged out the back door and quietly strangled, metaphorically speaking? And why is the Bush administration, by all accounts, seeking just such a result? Largely, it seems, because many of the timing systems we rely on use a pure atomic standard, with no leavening of leap seconds. These include most notably the American chain of global positioning system satellites. Almost all modern commercial transportation systems now rely on G.P.S. If those advocating an end to leap seconds can be believed, the disparity between atomic-clock-pegged G.P.S. chronometers and the leap-seconds-incorporating U.T.C. clock on your wall complicates navigation and raises the prospect of future catastrophic errors. Particularly because this discrepancy is, of course, increasing. With time.

Those who would retain leap seconds say close to the reverse. Killing leap seconds might well benefit our high technology, but it will be at our expense. Abolishing the leap second will simply export an ever-ratcheting discrepancy elsewhere, raising a host of potentially perilous problems, some foreseeable and some not. And these will also compound as our days and seasons drift free of the clock.

The most vocal advocates of leap seconds include practically all the world's astronomers, who need their systems to conform scrupulously to the Earth's rotation. Other threatened constituencies are satellite and deep-space mission controllers, and those whose work links them to the rising and setting of the sun. And then there are people like myself, who simply believe that our corporeal selves are tied to the Earth, or rather the dry bits of a watery planet suspended in a seemingly endless void, and that though our sphere may well turn there at a tempo we've recently discovered to be less than flawless, we live here, and not at the subatomic level. We benefit from a sun that has risen at a time determined by that rotation, and no other. To paraphrase Jorge Luis Borges, time may be the substance of which we are made, but the universe, alas, is real -- and so are we.

At the very least, there are grounds for concern that a potentially momentous decision might be made with absolutely no input on the issue from the vast majority of time's "consumers" -- meaning us, the non-specialists, the civilian population.

The leap seconds debate is finally freighted with philosophical issues. This temporal marker is a human construct. But it's positioned strategically between two different orders of scale -- the subatomic world of whizzing protons and electrons, and the extensive expanses of solar-system space, in which massive spheres ponderously rotate and wheel. The latter is of course the traditional time-keeping template, the model for the circular faces, orbiting hands, and inner wheelwork of the traditional mechanical time-keeper. The former represents the new paradigm that we may be on the verge of shifting to entirely, with scarcely any discussion.

We don't really know conclusively what will happen if we ignore the evidence of our senses and turn our backs on the cosmos. As one worried astronomer puts it, such a decoupling "would have unknown effects on civil and legal time, and ultimately on people." But clearly if we take those hourly reaffirmations of civilization's metronome too much for granted, as Swiss time runs inexorably down to the opening gavel of an obscure meeting of time-keeping mandarins, we do so at our own peril.

--Michael Benson is the author of Beyond: Visions of the Interplanetary Probes.



By Fiona MacGregor

September 22, 2005


Since the dawn of human existence, people have lived by the rising and setting of the sun -- but now American corporations want to change for ever the way time is measured.

An international argument has developed between British astronomers and scientists working for American telecommunications firms who have called for the abolition of the "leap second" -- the additional time unit used to keep modern atomic time-measuring systems in line with the earth's movement round the sun.

Removing that extra second would make some communication systems run more smoothly, but very slowly the clock would start to fall out of sync with the sun, eventually leading to 12 noon falling in the middle of the night.

The Royal Astronomical Society says the proposal has been raised by United States firms involved with the Global Positioning System, because design flaws mean GPS struggles to cope with leap seconds.

But the astronomers say losing the extra time would disrupt many other communications and "disconnect people" from the rotation of the earth.

Mike Hapgood, secretary of the RAS, said: "It's breaking the link between human time and the natural world."

It would be thousands of years before the change had a noticeable impact on the correlation between the clock and daylight, but the astronomers say it would immediately effect scientific projects, such as the satellite system used to track the progress of Hurricane Katrina.

The proposals to abolish the leap second from 2007 are to be discussed at a meeting of the International Telecommunications Union in Geneva.

Dr. Hapgood said: "This proposal is from the U.S. precision timing people involved with GPS, which was never designed very well to handle leap seconds -- although it could have been. They need to think again.

"We've followed the rules and they work for most situations."

There have been 21 leap seconds since 1972 and the next is planned at the end of 2005.

Their use is determined by the International Earth Rotation Service, sponsored by scientific bodies.

Those seeking to end the leap second say it causes problems such as GPS receivers losing track while the system adapts.