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:
“There comes a time in every rightly constructed boy’s life when he has a raging desire to go somewhere and dig for hidden treasure.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)
“We should not say that one man’s hour is worth another man’s hour, but rather that one man during an hour is worth just as much as another man during an hour. Time is everything, man is nothing: he is at the most time’s carcass.”
—Karl Marx (1818–1883)
“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)