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  2. Time - Wikipedia

    en.wikipedia.org/wiki/Time

    Time is the continuous progression of our changing existence that occurs in an apparently irreversible succession from the past, through the present, and into the future. [1] [2] [3] It is a component quantity of various measurements used to sequence events, to compare the duration of events (or the intervals between them), and to quantify rates of change of quantities in material reality or ...

  3. Time in physics - Wikipedia

    en.wikipedia.org/wiki/Time_in_physics

    In the International System of Units (SI), the unit of time is the second (symbol: s). It has been defined since 1967 as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom", and is an SI base unit. [12]

  4. A Brief History of Time - Wikipedia

    en.wikipedia.org/wiki/A_Brief_History_of_Time

    A Brief History of Time: From the Big Bang to Black Holes is a book on theoretical cosmology by the physicist Stephen Hawking.It was first published in 1988. Hawking wrote the book for readers who had no prior knowledge of physics.

  5. History of timekeeping devices - Wikipedia

    en.wikipedia.org/wiki/History_of_timekeeping_devices

    An Egyptian method of determining the time during the night, used from at least 600 BC, was a type of plumb-line called a merkhet. A north–south meridian was created using two merkhets aligned with Polaris, the north pole star. The time was determined by observing particular stars as they crossed the meridian. [24]

  6. Absolute space and time - Wikipedia

    en.wikipedia.org/wiki/Absolute_space_and_time

    Absolute, true and mathematical time, of itself, and from its own nature flows equably without regard to anything external, and by another name is called duration: relative, apparent and common time, is some sensible and external (whether accurate or unequable) measure of duration by the means of motion, which is commonly used instead of true ...

  7. Geologic time scale - Wikipedia

    en.wikipedia.org/wiki/Geologic_time_scale

    The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks).

  8. Philosophy of space and time - Wikipedia

    en.wikipedia.org/wiki/Philosophy_of_space_and_time

    Philosophy of space and time is the branch of philosophy concerned with the issues surrounding the ontology and epistemology of space and time.While such ideas have been central to philosophy from its inception, the philosophy of space and time was both an inspiration for and a central aspect of early analytic philosophy.

  9. Clock - Wikipedia

    en.wikipedia.org/wiki/Clock

    An analog pendulum clock made around 18th century. A clock or chronometer is a device that measures and displays time.The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month, and the year.