Light-foot
Encyclopedia
A light-foot is a nanosecond
, the time it takes light to travel about 1 foot. The earliest reference commonly given is to Admiral Grace Hopper
who oversaw the creation of COBOL
for the Navy and used to give out pieces of wire about a foot long to illustrate the eventual problem of building really 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 6" 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.
The Speed of light
is 299,792,458 m/s so it goes 0.299... m or about 30 cm (about 11.8 inches) in 1/1,000,000,000 (10−9) second which is a nanosecond.
Nanosecond
A nanosecond is one billionth of a second . One nanosecond is to one second as one second is to 31.7 years.The word nanosecond is formed by the prefix nano and the unit second. Its symbol is ns....
, the time it takes light to travel about 1 foot. The earliest reference commonly given is to Admiral Grace Hopper
Grace Hopper
Rear Admiral Grace Murray Hopper was an American computer scientist and United States Navy officer. A pioneer in the field, she was one of the first programmers of the Harvard Mark I computer, and developed the first compiler for a computer programming language...
who oversaw the creation of COBOL
COBOL
COBOL is one of the oldest programming languages. Its name is an acronym for COmmon Business-Oriented Language, defining its primary domain in business, finance, and administrative systems for companies and governments....
for the Navy and used to give out pieces of wire about a foot long to illustrate the eventual problem of building really 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 6" 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.
The Speed of light
Speed of light
The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...
is 299,792,458 m/s so it goes 0.299... m or about 30 cm (about 11.8 inches) in 1/1,000,000,000 (10−9) second which is a nanosecond.