Wiktionary
n. 1 An extremely accurate reference clock whose operation is based on an atomic process, typically the frequency of electromagnetic radiation associated with a specified energy-level transition in an element such as cesium. 2 (context proscribed English) A radio clock.
WordNet
n. a timepiece that derives its time scale from the vibration of atoms or molecules
Wikipedia
An atomic clock is a clock device that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element. Atomic clocks are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, to control the wave frequency of television broadcasts, and in global navigation satellite systems such as GPS.
The principle of operation of an atomic clock is not based on nuclear physics, but rather on atomic physics; it uses the microwave signal that electrons in atoms emit when they change energy levels. Early atomic clocks were based on masers at room temperature. Currently, the most accurate atomic clocks first cool the atoms to near absolute zero temperature by slowing them with lasers and probing them in atomic fountains in a microwave-filled cavity. An example of this is the NIST-F1 atomic clock, one of the national primary time and frequency standards of the United States.
The accuracy of an atomic clock depends on two factors. The first factor is temperature of the sample atoms—colder atoms move much more slowly, allowing longer probe times. The second factor is the frequency and intrinsic width of the electronic transition. Higher frequencies and narrow lines increase the precision.
National standards agencies in many countries maintain a network of atomic clocks which are intercompared and kept synchronized to an accuracy of 10 seconds per day (approximately 1 part in 10). These clocks collectively define a continuous and stable time scale, International Atomic Time (TAI). For civil time, another time scale is disseminated, Coordinated Universal Time (UTC). UTC is derived from TAI, but approximately synchronised, by using leap seconds, to UT1, which is based on actual rotation of the Earth with respect to the solar time.
Atomic Clock is the seventh studio album by Zion I, American hip hop duo consisting of Zumbi and Amp Live. It was released on Gold Dust Media in 2010.
An atomic clock is a time keeping device.
- Atomic Clock Ensemble in Space science project
- a clock updated by radio signals which is asometimes called an "atomic clock" Radio clock
- the clock as a measure for risk of catastrophic destruction Doomsday Clock
Usage examples of "atomic clock".
For instance, in 1976 Robert Vessot and Martin Levine of the Harvard-Smithsonian Astrophysical Observatory, together with collaboraters at the National Aeronautics and Space Administration (NASA), launched a Scout D rocket from Wallops Island, Virginia, that carried an atomic clock accurate to about a trillionth of a second per hour.
They hoped to show that as the rocket gained altitude (thereby decreasing the effect of the earth's gravitational pull), an identical earthbound atomic clock (still subject to the full force of the earth's gravity) would tick more slowly Through a two-way stream of microwave signals, the researchers were able to compare the rate of ticking of the two atomic clocks and, indeed, at the rocket's maximum altitude of 6,000 miles, its .
But on some future date I shall relate the tale of the atomic clock that failed.
They were synching their system with their own independent atomic clock.
Somewhere in the drive control network, an atomic clock was running slow, tweaked by a folded curl of space-time from the drive kernel.
Instead of getting the atomic clock, they'll be plugged into one of our computers.
Vonetta Beesley had always been as reliable as the atomic clock at Greenwich, by which all the nations of the world set their timepieces.
Navy's atomic clock in Fort Collins, Colorado, scrambled and descrambled the laser-beam transmission five times a second, and the resultant secure transmission wavered like an oldstyle short-wave radio.
If you want accuracy to within a fraction of a second per year, however, then the quartz watch will no longer serve and you will have to turn to something of the order of an atomic clock.
Nick was a gadget guy, and the clock received a signal from Colorado every midnight to reset it from the atomic clock there.
The Suit has no watch of his own but is relentlessly punctual, his rounds timed to the clocks of the subway, which are set in turn by radio, from an atomic clock in Nagoya.
Each opened box appears to have contained, along with other mechanisms, what appears to be an atomic clock.