What is a Nanosecond?

One nanosecond is 10^-9 seconds, or one billionth of a second. This means that there are one billion nanoseconds in one second; one billion is one followed by 9 zeros. It takes slightly more than a nanosecond for light to travel a single foot (0.3 meters); light travels at approximately 980 million feet per second (300 million meters per second). In science, a measure involving nanoseconds will usually be abbreviated to ns or nsec. While it is simply too small a measure to be useful in day-to-day life, the nanosecond has many important uses in chemistry and physics which both involve processes that occur in extremely small periods of time.

Computer scientists also make some measurements in nanoseconds as many processes in modern computing occur in very small time frames. The speed a computer takes to access its memory, for example, is commonly expressed in nanoseconds. In this case, lower numbers are better—a computer that can access its memory in 10 ns is faster than a computer that takes 30 ns to access its memory. Both numbers, however, represent very, very fast computing speeds. It is unlikely that an individual would be able to recognize the 20 ns time difference between the two processes.

Most of the uses of the nanosecond are in fields related to science and technology, such as electronics, optics, and communication. nanoseconds are often used to measure various aspects of electromagnetic waves such as frequency. In optics, very short nanosecond pulses of light or laser beams are used to gather precise images of fast-moving phenomenon such as chemical reactions. When many of these pulses occur in a very short period of time, a string of images are produced that allow scientists to view phenomenon at their leisure.

While the nanosecond is a very small measure of time, it is certainly not the smallest. A microsecond is somewhat larger than a nanosecond at 10^-6 seconds. Picoseconds and femtoseconds measure 10^-12 and 10^-15 seconds, respectively, and tend to have similar uses. Femtoseconds in particular are commonly used in optics to measure pulses used to take images at extremely small time frames. None of these units have practical applications to most people, but physicists, chemists, and technologists often need such small units.

Grace Hopper, a United States naval officer and computer scientist, was known for her lectures on computer science. She is primarily known for developing the first compiler for a programming language. At her lectures, she was known to hand out lengths of wire that were just under 1 foot (0.3 meters) long to show the distance that light traveled in a nanosecond; she did this to explain why satellite communication was not instantaneous.