Tom Van Baak has set up an atomic-clock lab at his home in his Bellevue, Washington. *
Photo: Quinn Norton * View Slideshow 
BELLEVUE, Washington -- Tom Van Baak's spare upstairs bedroom looks like a cross between the control center of a remote polar outpost and the inner sanctum of a Victorian mad scientist. In reality, it's a home-built lab dedicated to the study of time.
One wall is stacked with a small museum's worth of old nautical clocks, thin slabs of quartz, vacuum tubes of unknown purpose and a few metronomes. Another wall is dominated by shelves overflowing with metal boxes sporting dials, knobs, flashing LEDs and constantly shifting digital displays. A sealed metal cylinder resting on a paint-splattered stepladder bears the not-quite-reassuring sticker, "Cesium Device. Not Radioactive."
"If you have one clock ... you are peaceful and have no worries," says Van Baak, fingering a length of cable connecting two of his machines. "If you have two clocks ... you start asking, 'What time is it, really?'"
Van Baak is in a better position to answer that question than most. He's part of a community of about 400 geek hobbyists taking advantage of a glut of surplus precision timekeeping gear to pursue a serious interest in very precise timekeeping. They call themselves Time Nuts, and they spend their spare cycles collecting, repairing, tweaking -- and occasionally using -- super-precise clocks.
With the end of the Cold War, and with telecommunications technology advancing rapidly, surplus stores and eBay have filled up with discarded precision time equipment once beyond the reach of all but governments. Cesium clocks, rubidium clocks and even the occasional hydrogen maser can be had for less than a decent laptop. A recent search on eBay turned up an HP 5061B cesium standard for sale for $2,000, and you can get a telecom surplus rubidium standard for less than $400. Some of this equipment costs upwards of $50,000 new.
Their access to once-forbidden technology lets the time hackers play in a realm of precision that underpins the modern technological world. A select few, like Van Baak, have started exploring the underpinnings of the universe .
A retired Unix kernel programmer, Van Baak began buying time instruments a decade ago, slowly building what today is probably the best-equipped, individually owned time lab in the world, exceeding the capability of many national labs. His gear lets him perform some impressive experiments. Two years ago, he realized he'd acquired the capability to offer his children a demonstration of one of the effects predicted by Einstein's general theory of relativity -- a demonstration that Einstein himself couldn't have performed with the equipment of his day.
The theory says time passes slowly for someone near a massive object, as measured relative to someone farther away. On Earth, this effect is so small as to be undetectable to all but the most precise equipment, putting demonstrations beyond the reach of, say, a typical high school science fair. Consequently, "kids grow up thinking relativity is only for really fast speeds or really heavy gravity," says Van Baak.
He wanted his children to see that relativity is proportional. So he loaded the family's blue minivan with portable power supplies, monitoring equipment, and three HP 5071 cesium clocks. Three, because time is always marked relative to other clocks: More clocks mean more accurate time. With his three kids and some camping gear in tow, he drove the winding roads spiraling up Washington's Mt. Rainier and checked the family into a lodge 5,319 feet above sea level.
They hiked the trails, and the kids relaxed with board games and books, while in the imperceptibly lessened gravity, time moved a little bit faster than at home. Van Baak found himself explaining to park rangers more than once why a minivan filled with inscrutable equipment was idling in front of the national park lodge for hours on end. But the effort paid off. When the family returned to the suburbs two days later, the cesium clocks were off by the precise amount relativity predicted. He and his family had lived just a little more life than the neighbors.
"It was the best extra 22 nanoseconds I've ever spent with the kids," Van Baak says.
Existential thrills aside, the Time Nuts dabble in the practical as well. John Ackerman, an attorney with a technology company, offers super-accurate time over the internet to anyone who wants it, courtesy of four of the most accurate NTP (network time protocol) servers in the world.
Located in a pegboard-lined basement in his Dayton, Ohio home, three of Ackerman's servers use external sources: GPS and LORAN-C navigation broadcasts, and the WWVB radio station that broadcasts U.S. standard time from the National Institute of Standards and Technology in Boulder. His fourth machine, though, is the most impressive: It has its own cesium clock. A rack-mounted PC watches the cesium clock's output and uses it to keep the other clocks in line during the microsecond chasms between broadcast pings.
Ackerman fell into the time rabbit hole while practicing his other hobby, ham radio. Precise frequencies are important when trying to get to the right bit of radio spectrum, and from his pursuit of the perfect frequency it was easy to get drawn into clocks. "It led me into buying all sorts of crap from eBay," he admits.
It's a hobby that feeds on itself: A good clock always needs a better clock to set it. "You always have to have a reference frequency," says Ackerman. "If you get the next new good thing ... you have to measure it against something even better." It's a source of pride to Ackerman that his four machines keep time within 100 nanoseconds of each other.
That fastidiousness is typical in both the amateur and professional timekeeping communities, where people are drawn first to the idea of finding precision in the physical world. Consistently, they tell stories of an early fascination with looking ever closer at something, trying to understand its exact boundaries. Fundamental to the field of precise time is that it will never be perfect. With every new level of accuracy comes a new frame of reference for error. Time has an intractable precision -- you can spend your days always moving closer to the ever-unreachable now.
The time hackers' commitment has earned them the respect of professional horologists, some of whom lurk on the Time Nuts mailing list to offer advice -- or even unofficial tech support. One participant, Rick Karlquist, is a celebrity of sorts in the group. Now an electrical engineer for Agilent Labs, in the 1980s Karlquist helped design two of the precision clocks now showing up in the surplus market.
At Agilent's Sunnyvale, California, campus, Karlquist shows off one of his inventions. It's a "hockey puck" -- a silver discus on a circuit board the size of a PC card slot. Inside is a quartz-crystal-based oscillator that can keep its accuracy through 100-degree Celsius variations in temperature. Originally designed for Qualcomm CDMA towers, this was the clock that could keep you talking from Barrow, Alaska, to Phoenix, Arizona. Now, it's a popular plaything in the hands of the Time Nuts, who appreciate its legendary indestructibility.
Karlquist's other achievement is the HP 5071 cesium clock -- the model Van Baak hauled up the slopes of Mt. Rainier. "The 5071 was indisputably the best commercial clock that's ever been made," Karlquist says. There's consensus on this in the time community. The 5071 is a damn fine clock, and a rare $30,000 find on eBay. At one point, explains Karlquist, it made up 80 percent of the weighting of international atomic time.
On Agilent's campus, though, the 5071 is literally a museum piece -- an exhibit in a small museum of Agilent devices, most of them dating from when Agilent was Hewlett Packard's R&D arm. That's why Karlquist feels a duty to the Time Nuts -- it's how he keeps his creations alive. "Most of the pro community has moved on," he says. "If I didn't support them, it would be impossible to get them to work.... I can't resist coming in and sounding like an expert," he says, laughing.
People like Karlquist built a backbone of time technology that stretches from obscure government labs to our mobile phones and e-mail servers. For curious enthusiasts, the chance to explore and understand that hidden connection is now wide open, and cheap surplus.
"Precision time is the infrastructure on which most modern technology depends," says Van Baak. Unlock the black boxes of the computers, travel, telecommunications and transportation, he says, and you get clocks.
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Part one of a two-part series.
Tomorrow: At a government lab in Colorado, the future of precision-clock research is unfolding. It's no longer just about keeping accurate time.
The Bleeding Edge of Time 
Gallery: Time Hackers Tinker With Their Atomic Toys 
How Super-Precise Atomic Clocks Will Change the World in a Decade 
Gallery: Step Inside America's Time Lab 
Amateur Time Hackers Play With Atomic Clocks at Home Gallery: Time Hackers Tinker With Their Atomic Toys