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For example, considered over the total time-span of Earth (4.6 billion years), a clock set in a geostationary position at an altitude of 9,000 meters above sea level, such as perhaps at the top of Mount Everest (prominence 8,848 m), would be about 39 hours ahead of a clock set at sea level.
A clock used to time a full rotation of the Earth will measure the day to be approximately an extra 10 ns/day longer for every km of altitude above the reference geoid." [ 35 ] Travel to regions of space where extreme gravitational time dilation is taking place, such as near (but not beyond the event horizon of) a black hole , could yield time ...
The unit of TT is the SI second, the definition of which is based currently on the caesium atomic clock, [3] but TT is not itself defined by atomic clocks. It is a theoretical ideal, and real clocks can only approximate it. TT is distinct from the time scale often used as a basis for civil purposes, Coordinated Universal Time (UTC).
Over the last 78 years, the clock’s time has changed according to how close scientists believe the human race is to total destruction. Some years the time changes, and some years it doesn’t.
To maintain synchrony between the internal clock and the external environment, zeitgebers, such as the sun rising, causes wakefulness in humans. This ability to align behaviors such as feeding and activity to the external environmental cycle is a process called entrainment .
For Earth's surface with respect to infinity, z is approximately 7 × 10 −10 (the equivalent of a 0.2 m/s radial Doppler shift); for the Moon it is approximately 3 × 10 −11 (about 1 cm/s). The value for the surface of the Sun is about 2 × 10 −6, corresponding to 0.64 km/s.
An equation clock is a mechanical clock which includes a mechanism that simulates the equation of time, so that the user can read or calculate solar time, as would be shown by a sundial. The first accurate clocks, controlled by pendulums , were patented by Christiaan Huyghens in 1657.
In physics, time is defined by its measurement: time is what a clock reads. [1] In classical, non-relativistic physics, it is a scalar quantity (often denoted by the symbol ) and, like length, mass, and charge, is usually described as a fundamental quantity. Time can be combined mathematically with other physical quantities to derive other ...