Alex Pasternack describes how timekeeping is the measurement of the passage of a second, which equates to how long it takes for a certain amount of radiation to be given off by a cesium atom in the universe.

The primary aim of timekeeping is to measure the passage of a second. To be precise, that is equivalent to the amount of time it takes for the hyperfine radiation given off by a cesium-133 atom at its ground state as it transitions between energy levels, and its electrons oscillate exactly 9,192,631,770 times.

These days, counting a second depends upon firing a microwave beam at one of these cesium atoms and counting the effect on its electrons. At that scale, the slightest aberration can knock a clock off its count. And then there are the effects of gravity, which Einstein’s theory of special relativity showed can shift the pace of time.

“At the nanosecond level—a billionth of a second—every clock has its own personality,” Matsakis wrote in an email. Each clock will tick faster or slower at certain times, and generally, scientists can correct for this using software. The trickier part is understanding the rate–sometimes sudden, sometimes slow—at which a clock’s ticking may be changing. “We must be on the lookout for deviations from the predicted behavior, and be sure to predict well.”…

“Once I had this definition of time, that it’s a coordinate that you can measure the evolution of in a closed system,” Matsakis said. “Now, I think of time as something that, stripped down to its essence, is a measure of interactions,” an idea based on Einstein’s theory of relativity, which pins time and space to the relative motion of objects. “It’s an intriguing thought: if you don’t have interactions, time is irrelevant.”

He offers an example that begins at the end of time. “One way that time could stop is if the universe could reach a cold death. If our universe expands forever, and the suns die out, and they become black holes which evaporate over eons, what’s left is a rarefied gas, a cold gas that’s uniform across the universe. With everything the same, how can you have time? There’d be nothing to measure time. Time would stop, and not with a bang. It would just peter out.”

The relative interactions that govern the movement of time explain why events in the universe don’t easily fit along a timeline. “Imagine that people witness Al Capone robbing a bank in 1930,” he said. “Then, a supernova a thousand light-years away is observed somewhere on Earth in 1987. Did the star explode first, or was the bank robbery first? It depends on the observer.”

In an email later, I mentioned Nieztsche’s proposal of eternal return. Matsakis shot back: “It is very hard to define fundamental things. I haven’t tried to define ‘place.’ Socrates spent years trying to define justice. Maybe they were right about him corrupting the youth.”

It was Aristotle’s contemporaries who first mastered the calculation of the passage of time, or chronos, and it was they who also recognized another kind of time, kairos—the moments that define our pleasures and our pains and our deepest feelings and thoughts.In other words, the kind of time that can’t be metered by any clock.

Tensions linger between this sense of “time,” which Henri Bergson would later describe as “duration,” and the tick-tocks of “the time” overseen by the timekeepers. Now more than ever before, argues Douglas Rushkoff in Present Shock, distractions keep the latter version of time in a kind of tug of war with the former.

“We spent centuries thinking of hours and seconds as portions of the day,” Rushkoff told David Pescovitz last year, “But a digital second is less a part of a greater minute, and more an absolute duration, hanging there like the number flap on an old digital clock.” The rush of the present and its seemingly infinite, hyperlinked possibilities means “a diminishment of everything that isn’t happening right now—and the onslaught of everything that supposedly is.”

But according to time, not everything is happening at once, as Wheeler joked. Could the Master Clock, I wondered, with its steady, orderly pace, remind us that the world isn’t moving any faster?

But not even this ticking will be the same in the future. With new clocks, the way that time is counted will change. And in time, the definitions of time will change too, if not the questions that endlessly circle it.

“What I tell people is, I can’t tell you what time is,” Matsakis said, “but I can tell you what a second is” (Pasternack 2014).

Pasternack, Alex. 2014. “How the master clock sets the time for the world.” Motherboard, November 7, 2014. https://motherboard.vice.com/en_us/article/ 3dkd5b/demetrios-matsakis-and-the-master-clock