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  2. Orders of magnitude (length) - Wikipedia

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

    The nanometre ( SI symbol: nm) is a unit of length in the metric system equal to 10−9 metres ( ⁠ 1 1 000 000 000⁠ m = 0.000 000 001 m ). To help compare different orders of magnitude, this section lists lengths between 10 −9 and 10 −8 m (1 nm and 10 nm). 1 nm – diameter of a carbon nanotube.

  3. Light-year - Wikipedia

    en.wikipedia.org/wiki/Light-year

    A light-year, alternatively spelled light year ( ly or lyr[ 3] ), is a unit of length used to express astronomical distances and is equal to exactly 9,460,730,472,580.8 km ( Scientific notation: 9.4607304725808 × 10 12 km), which is approximately 5.88 trillion mi.

  4. History of the metre - Wikipedia

    en.wikipedia.org/wiki/History_of_the_metre

    As the metre had to be equal to one ten-millionth of this distance, it was defined as 0.513074 toise or 3 feet and 11.296 lines of the Toise of Peru, which had been constructed in 1735 for the French Geodesic Mission to the Equator. When the final result was known, a bar whose length was closest to the meridional definition of the metre was ...

  5. 1000 metres world record progression - Wikipedia

    en.wikipedia.org/wiki/1000_metres_world_record...

    The first world record in the women's 1000 metres was recognised by the IAAF in 1922. 13 world records have been ratified by the IAAF in the event. Time Athlete

  6. History of the metric system - Wikipedia

    en.wikipedia.org/wiki/History_of_the_metric_system

    Units in everyday use by country as of 2019 The history of the metric system began during the Age of Enlightenment with measures of length and weight derived from nature, along with their decimal multiples and fractions. The system became the standard of France and Europe within half a century. Other measures with unity ratios [Note 1] were added, and the system went on to be adopted across ...

  7. Metre - Wikipedia

    en.wikipedia.org/wiki/Metre

    The metre (or meter in US spelling; symbol: m) is the base unit of length in the International System of Units (SI). Since 2019, the metre has been defined as the length of the path travelled by light in vacuum during a time interval of ⁠ 1 299 792 458⁠ of a second, where the second is defined by a hyperfine transition frequency of caesium.

  8. Age of the universe - Wikipedia

    en.wikipedia.org/wiki/Age_of_the_universe

    In physical cosmology, the age of the universe is the time elapsed since the Big Bang.Astronomers have derived two different measurements of the age of the universe: [1] a measurement based on direct observations of an early state of the universe, which indicate an age of 13.787 ± 0.020 billion years as interpreted with the Lambda-CDM concordance model as of 2021; [2] and a measurement based ...

  9. 1000 metres - Wikipedia

    en.wikipedia.org/wiki/1000_metres

    The 1000 metres is an uncommon middle-distance running event in track and field competitions. The 1000 yards , an imperial alternative, was sometimes also contested. [ 1 ] [ 2 ]