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  2. Orders of magnitude (time) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(time)

    Orders of magnitude (time) An order of magnitude of time is usually a decimal prefix or decimal order-of-magnitude quantity together with a base unit of time, like a microsecond or a million years. In some cases, the order of magnitude may be implied (usually 1), like a "second" or "year". In other cases, the quantity name implies the base unit ...

  3. Unit of time - Wikipedia

    en.wikipedia.org/wiki/Unit_of_time

    A unit of time is any particular time interval, used as a standard way of measuring or expressing duration. The base unit of time in the International System of Units (SI), and by extension most of the Western world, is the second, defined as about 9 billion oscillations of the caesium atom. The exact modern SI definition is " [The second] is ...

  4. Femtosecond - Wikipedia

    en.wikipedia.org/wiki/Femtosecond

    A femtosecond is a unit of time in the International System of Units (SI) equal to 10 −15 or 1⁄1 000 000 000 000 000 of a second; that is, one quadrillionth, or one millionth of one billionth, of a second. [ 1 ] A femtosecond is to a second, as a second is to approximately 31.69 million years.

  5. Light-second - Wikipedia

    en.wikipedia.org/wiki/Light-second

    The light-second is a unit of length useful in astronomy, telecommunications and relativistic physics. It is defined as the distance that light travels in free space in one second, and is equal to exactly 299 792 458 m (approximately 983 571 055 ft or 186 282 mi). Just as the second forms the basis for other units of time, the light-second can ...

  6. Attosecond - Wikipedia

    en.wikipedia.org/wiki/Attosecond

    10−18 s. An attosecond (abbreviated as as) is a unit of time in the International System of Units (SI) equal to 10 −18 or 1 ⁄ 1 000 000 000 000 000 000 (one quintillion) of a second. [1] An attosecond is to a second, as a second is to approximately 31.69 billion years. [2]

  7. Second - Wikipedia

    en.wikipedia.org/wiki/Second

    Symbol. s. The second (symbol: s) is a unit of time, historically defined as 1⁄86400 of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each (24 × 60 × 60 = 86400). The current and formal definition in the International System of Units (SI) is more precise:

  8. Geologic time scale - Wikipedia

    en.wikipedia.org/wiki/Geologic_time_scale

    The geologic time scale, proportionally represented as a log-spiral with some major events in Earth's history. A megaannus (Ma) represents one million (10 6) years. 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 ...

  9. Attosecond physics - Wikipedia

    en.wikipedia.org/wiki/Attosecond_physics

    High harmonic generation in krypton.This technology is one of the most used techniques to generate attosecond bursts of light. Attosecond physics, also known as attophysics, or more generally attosecond science, is a branch of physics that deals with light-matter interaction phenomena wherein attosecond (10 −18 s) photon pulses are used to unravel dynamical processes in matter with ...