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 29.98 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 use of the term is by
- International System of Units
- Jiffy (time)
- Orders of magnitude (time)
- 0.5 nanoseconds (0.5 ns) – the average life of a molecule of positronium hydride
- 1.0 nanosecond – cycle time for radio frequency 1 GHz (1 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 – 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 – cycle time for frequency 100 MHz (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
- 1000 nanoseconds - one microsecond
Light travels ~29.979 cm in one nanosecond, meaning that, technically, a light-foot is ~1.0167 nanoseconds.
"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."
processor. multi-core 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 , who used to give out pieces of wire about a foot long to illustrate the eventual problem of building very high speed computers.Grace Hopper is to Admiral  Another early reference commonly given