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.
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Famous quotes containing the words constructed, time and/or standards:
“How marvellous it all is! Built not by saints and angels, but the work of men’s hands; cemented with men’s honest blood and with a world of tears, welded by the best brains of centuries past; not without the taint and reproach incidental to all human work, but constructed on the whole with pure and splendid purpose. Human, and yet not wholly human—for the most heedless and the most cynical must see the finger of the Divine.”
—Archibald Philip Primrose, 5th Earl Rosebery (1847–1929)
“Have you ever turned toward an intellectual in a time of authentic anguish and encountered his light appraisal, or evasion, of your grief? Or turned to him in a situation of light import only to be met with a heavy, superfluous solemnity?”
—Margaret Anderson (1886–1973)
“Chief among our gains must be reckoned this possibility of choice, the recognition of many possible ways of life, where other civilizations have recognized only one. Where other civilizations give a satisfactory outlet to only one temperamental type, be he mystic or soldier, business man or artist, a civilization in which there are many standards offers a possibility of satisfactory adjustment to individuals of many different temperamental types, of diverse gifts and varying interests.”
—Margaret Mead (1901–1978)