Constructed Time Standards
International Atomic Time (TAI) is the primary international time standard from which other time standards, including UTC, are calculated. TAI is kept by the BIPM (International Bureau of Weights and Measures), and is based on the combined input of many atomic clocks around the world, each corrected for environmental and relativistic effects. It is the primary realisation of Terrestrial Time.
Coordinated Universal Time (UTC) is an atomic time scale designed to approximate Universal Time. UTC differs from TAI by an integral number of seconds. UTC is kept within 0.9 second of UT1 by the introduction of one-second steps to UTC, the "leap second". To date these steps have always been positive.
Standard time or civil time in a region deviates a fixed, round amount, usually a whole number of hours, from some form of Universal Time, now usually UTC. The offset is chosen such that a new day starts approximately while the sun is at the nadir. See Time zone. Alternatively the difference is not really fixed, but it changes twice a year a round amount, usually one hour, see Daylight saving time.
Read more about this topic: Time Standard
Famous quotes containing the words constructed, time and/or standards:
“This house was designed and constructed with the freedom of stroke of a forester’s axe, without other compass and square than Nature uses.”
—Henry David Thoreau (1817–1862)
“I am already kindly disposed towards you. My friendship it is not in my power to give: this is a gift which no man can make, it is not in our own power: a sound and healthy friendship is the growth of time and circumstance, it will spring up and thrive like a wildflower when these favour, and when they do not, it is in vain to look for it.”
—William Wordsworth (1770–1850)
“Men are rewarded for learning the practice of violence in virtually any sphere of activity by money, admiration, recognition, respect, and the genuflection of others honoring their sacred and proven masculinity. In male culture, police are heroic and so are outlaws; males who enforce standards are heroic and so are those who violate them.”
—Andrea Dworkin (b. 1946)