Atomic clock: We now use an atomic standard of time, which is based on the periodic vibrations produced in a cesium atom. This is the basis of the cesium clock, sometimes called atomic clock, used in the national standards. It is highly accurate.

An all-optical atomic clock, recently demonstrated by researchers at the US National Institute of Standards and Technology (NIST; Gaithersburg, MD), produces about 1 quadrillion “ticks” per second and promises to be as much as 1000 times more accurate than the world’s current standard in time measurement-cesium-based …

The current definition of a second, the SI Unit of time states that ‘a second is the duration of 9,192,631,770 cycles of radiation due to the transition between energy levels of Caesium-133 atom kept at a temperature of 0K Atomic clocks are the most accurate time and frequency standards known.

There are atomic (Cesium) clocks capable of measuring time with an accuracy of 1 part in 1011.

Measurement of Time Time is measured using a clock. As a standard,atomic standard of time is now used, which is measured by Cesium or Atomic clock. In Cesium clock, a second is equal to 9,192,631,770 vibrations of radiation from the transition between two hyperfine levels of cesium-133 atom.

Cesium atomic clock is based on the number of oscillating radiations produced.. ONE SECOND is equal to 9,192,631,770 times the Radiation produced by Cesium-133 isotope.

Accuracy of a measurement is how close the measured value is to the true value. Precision is the resolutionor closeness of a series of measurements of a same quantity under similar conditions.

Time is measured with instruments such as a clock or calendar. These instruments can be anything that exhibits two basic components: (1) a regular, constant, or repetitive action to mark off equal increments of time, and (2) a means of keeping track of the increments of time and of displaying the result.

Planck time is roughly 10−44 seconds. However, to date, the smallest time interval that was measured was 10−21 seconds, a “zeptosecond.” One Planck time is the time it would take a photon travelling at the speed of light to cross a distance equal to one Planck length.

A research team at the University of Central Florida has demonstrated the fastest light pulse ever developed, a 53-attosecond X-ray flash. At one-quintillionth of a second, an attosecond is unimaginably fast. In 53 attoseconds, light travels less than one-thousandth of the diameter of a human hair.