The Essence of Time: Monumentally Important Clocks
From humanity's earliest days we've kept a close eye on time. The way we recorded its passage revealed what was important to us: To stay on schedule for planting and harvesting, the ancients tracked the seasons; for rituals and divination, they kept watch on the movements of the stars and planets; clocks allowed sailors to calculate longitude as they explored the world. Today, ubiquitous, accurate and synchronized, clocks keep civilization aligned.
The world’s highest-tech clocks, advanced atomic clocks are now so accurate they vary less than the orbit of the Earth. At the lab responsible for keeping official time in America, the National Institute of Standards and Technology in Boulder, Colorado, moving an atomic clock from one floor to another can require recalibration to correct for the relativistic effects of a change in altitude. The greater the pull of gravity, the slower a clock runs.
We weren't always such obsessive second-splicers. Hours were standardized only a few hundred years ago. Before that, sundials marked 12 hours of day and 12 of night, year-round: A daylight hour expanded in length in summer and contracted in winter.
Time-keeping devices like Stonehenge, the Aztec calendar, and the Antikythera Mechanism were more about keeping people on time for seasonal and celestial appointments, not daily ones. Now, an entirely new type of clock is being built in west Texas. Designed to last 10,000 years, it trumps all other clocks in its long-term view. To remind us of its roots, we've gathered some of the most important time-keeping devices throughout the ages.
Above:
NIST-F1 Cesium clock
The NIST-F1 cesium fountain clock keeps official U.S. time at the National Institute of Standards and Technology. Once every 60 million years, the clock might gain or lose a second. The lab operates even more advanced clocks , accurate out to 3.7 billion years.
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U S Atomic Clock - News
At the lab responsible for keeping official time in America, the National Institute of Standards and Technology in Boulder, Colorado, moving an atomic clock from one floor to another can require recalibration to correct for the relativistic effects of
The temperature is reported in real time, and the time is synchronized with the United States Atomic Clock via a Global Positioning System (GPS) satellite receiver. The time is obtained from at least one of 24 satellites orbiting the earth at some
This means that the Mecca Clock, and anyone who sets a watch by it, deviates from standard time by roughly 21 minutes. To most of us, protesting Greenwich Mean Time (or its Greenwich-based modern successor, Universal Coordinated Time) may seem bizarre.
It's agonizingly true now that the Internet has handed us not-ink-stained wretches and a constantly ticking atomic clock where 'breaking' news is measured in split seconds instead of hours. Which is the real reason why we heard more than we really
Similarly at present, under the pretext of Talibanisation of Pakistan and lawlessness in the country, which has been planted by CIA, RAW and Mossad, US is preparing ground to 'denculearise' Pakistan by propagating in the world that Pakistan's atomic
Atomic clock is smallest on the market « physics4me
U.S. researchers have developed the world's smallest atomic clock business. Known as the atomic clock SA.45s size of the chip (CSAC), it could be yours for only $ 1500. The clock, originally developed for military use, is about the size of a matchbox, weighing about 35 grams and has a power requirement of only 115 mW. This is not your timepiece every day, the team behind the claim that the clock could have a variety of applications and large-scale, off bombs in search of oil. This clock was developed in conjunction with Symmetricom, Draper Laboratory and Sandia National Laboratories in the United States. The clock comprises a highly compact “physics package” that contains the caesium atoms used and sits on a circuit board within a tiny box. The caesium atoms are held within a resonance cell and are heated to a vapour state by plates situated at the top and bottom of the package. An optimized vertical-cavity surface-emitting laser (VCSEL) is shone through the vapour, causing excitation in the caesium atoms. The laser light is modulated by a microwave signal generator on the chip. This allows the laser’s single beam to excite the caesium atoms at two different energy levels. Interference between these two levels is then detected by a photodiode that forms part of a feedback loop. The loop optimizes the number of photons absorbed by the caesium atoms. The clock indicates that 1 s has elapsed after counting exactly 4596,315,885 cycles of the microwave oscillator signal.
All the components on the PCB are optimized for power efficiency at the smallest size possible. As a result, the circuitry around the physics package consumes about 95 mW, with the physics package itself consuming about 10 mW. Allowing for production faults, the CSAC has a total power consumption of only 115 mW, according to Steve Fossi, Symmetricom’s director of business development. In 2004 Physics World reported that John Kitching and his team at the US National Institute of Standards and Technology (NIST) in Boulder, Colorado, created what was then the most compact and portable chip-scale atomic clock. So what is different about this latest device? According to Kitching, this new product is essentially a commercial version of the work pioneered by his group at NIST between 2001 and 2005. “The Symmetricom collaboration also had an active research programme during that time that was funded in parallel with ours by the Defense Advanced Research Project Agency [DARPA].” While the Symmetricom and NIST clocks are about the same size, the main advantage of this new clock is that the power required to run it is much less than any previous commercial atomic clock: 115 mW, compared with more than 1 W for all other atomic clocks. “This means it will open many new applications for precision timing, particularly those where only battery power is available,” says Kitching. The clock could find a use in disabling improvised explosive devices (IED) or roadside bombs that are detonated wirelessly using everything from mobile phones to toy remote controls. Such bombs can be disabled using portable jammers that block all communications signals in the area. While this solves the immediate problem of the bomb, it also prevents friendly forces from using radio communications. The CSAC would provide the precise timing required to jam bomb-related communications while allowing friendly signals to get through. The device could also be used in places where GPS timing signals are not available, for example in deep-sea diving, mining and seismic research. In particular, the clocks could be deployed in underwater sensors that rely on the precision timing of seismic signals for oil and gas exploration. In this case, the clocks on each sensor would need to be accurate, small and run on very low power so that the sensors could remain underwater for prolonged periods of time. The CSAC has only 10–20% of the power requirement of existing sensor clocks but is about a 100 times more accurate…. http://physicsworld.
Go to the U.S. Naval Observatory website or the NIST 'site. Though NIST gets it's data frm USNO atomic-clock
Side note - broken clock is more accurate then an atomic watch for the reason u mentioned so it's far from being the worse. ;)
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Official U.S. Time
Clock for all U.S. time zones provided by the two time agencies of the United States: a civilian agency, the National Institute of Standards and Technology (NIST), and its military counterpart, the U.S. Naval Observatory (USNO).
The official U.S. time - clock
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Atomic clock - Wikipedia, the free encyclopedia
US National Bureau of Standards. Invented. 1949. The master atomic clock ensemble at the ... May 2009- JILA's strontium optical atomic clock is based on neutral atoms. ...
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