|Look up nanosecond in Wiktionary, the free dictionary.|
A nanosecond is equal to 1000 picoseconds or 1⁄1000 microsecond. Because the next SI unit is 1000 times larger, times of 10−8 and 10−7 seconds are typically expressed as tens or hundreds of nanoseconds.
Light travels approximately 29.9 centimeters in 1 nanosecond. This is equivalent to 11.8 inches, leading to some to refer to a nanosecond as a light-foot. The earliest reference commonly given is to Admiral Grace Hopper, who used to give out pieces of wire about a foot long to illustrate the eventual problem of building very high speed computers. If it takes light a nanosecond to go a foot (in a vacuum, slower in copper), then a computer built with parts connected by half this distance, 15 centimetres (5.9 in) of wire, would take at least a nanosecond to send data to a part and get a response. The solution, developed in Hopper's lifetime, was first the integrated circuit and later the multi-core processor.
"Once she presented a piece of wire about a foot long, and explained that it represented a nanosecond, since it was the maximum distance electricity could travel in wire in one-billionth of a second. She often contrasted this nanosecond with a microsecond - a coil of wire nearly a thousand feet long - as she encouraged programmers not to waste even a microsecond. "
Light travels ~29.979 cm in one nanosecond, meaning that, technically, a light-foot is ~1.0167 nanoseconds.
- 0.5 nanoseconds (0.5 ns) – the average life of a molecule of positronium hydride.
- 1.0 nanosecond (1.0 ns) – cycle time for radio frequency 1 GHz (1×109 hertz), an inverse unit. This corresponds to a radio wavelength of 1 light-nanosecond or 0.3 m, as can be calculated by multiplying 1 ns by the speed of light (approximately 3×108 m/s) to determine the distance traveled.
- 1.0 nanosecond (1.0 ns) – cycle time for a 1 GHz processor. As of 2011, common processors have frequencies around 1–3.5 GHz, so the cycle time is somewhat shorter than a nanosecond.
- 1.017 nanoseconds (approximately) – time taken for light to travel 1 foot in a vacuum.
- 3.33564095 nanoseconds (approximately) – time taken for light to travel 1 metre in a vacuum. (In air or water light travels more slowly; see index of refraction)
- 10 nanoseconds – one "shake", (as in a "shake of a lamb's tail") approximate time of one generation of a nuclear chain reaction with fast neutrons
- 10 nanoseconds (10 ns) – cycle time for frequency 100 megahertz (1×108 Hertz), radio wavelength 3 m (VHF, FM band)
- 12 nanoseconds – half-life of a K meson
- 20–40 nanoseconds – time of fusion reaction in a hydrogen bomb
- 77 nanoseconds – a sixth (a 60th of a 60th of a 60th of a 60th of a second)
- 100 nanoseconds – cycle time for frequency 10 MHz, radio wavelength 30 m (shortwave)
- 333 nanoseconds – cycle time of highest medium wave radio frequency, 3 MHz
- 500 nanoseconds – T1 time of Josephson phase qubit (see also Qubit) as of May 2005
- David Mermin (2009). It's About Time: Understanding Einstein's Relativity. Princeton, New Jersey: Princeton University Press. p. 22. ISBN 978-0-691-14127-5.
- "Grace Murray Hopper". New Haven, CT: Yale University. 1994.
- "Grace Hopper - Nanoseconds". YouTube. 2012-01-25. Retrieved 2013-05-23.
- Gamow, George (1961), One, Two, Three... Infinity: Facts & Speculations of Science (3rd ed.), Courier Dover Publications, p. 77, ISBN 0486256642.
- "Official BIPM definition of the metre". BIPM. Retrieved 2008-09-22.