Light foot (unit)

As Lichtfuß ( English light-foot ) is semi jokeful the time period referred to that the light or other electromagnetic waves in vacuum or approximately in air need to the route of a foot (1 ft) to cover, or about 30 centimeters. This time is about one nanosecond (ns) .

1 light foot ≈ 1 ns

The speed of light in a vacuum is exact:

${\displaystyle c_{0}=299\,792\,458\,{\frac {\rm {m}}{\rm {s}}}=2{,}997\,924\,58\cdot 10^{8}\,{\frac {\rm {m}}{\rm {s}}}}$

Converted from meters per second to millimeters per nanosecond, the speed of light is:

${\displaystyle c_{0}=299,792\,458\,{\frac {\rm {mm}}{\rm {ns}}}\approx 30\,{\frac {\rm {cm}}{\rm {ns}}}}$

The light thus travels a distance of around 30 cm in one nanosecond.

The advantage of the light foot is that the reference length, which is hardly imaginable for people in the case of the distance traveled by light in one second, is traced back to a “human dimension” in the truest sense, namely a foot, and is therefore easy to imagine. Incidentally, the associated time of flight in the order of magnitude of a nanosecond is a period of time that is of great practical importance in many areas of physics and electrical engineering . In addition, the period of an electromagnetic oscillation of 1 GHz ( gigahertz ) is also 1 ns (see also: microwaves ).

The Lichtfuß as a unit of time is based on the in astronomy as a unit length normal light years to see.

literature

• George Gamow : One Two Three ... Infinity - Facts and Speculations of Science . Dover Publications, New York 1961, ISBN 0-486-25664-2 , p. 77, ( page no longer available , search in web archives: selfdefinition.org ) (PDF; 14.3 MB; English)
• N. David Mermin : It's about Time: Understanding Einstein's Relativity . Princeton University Press, 2005, ISBN 978-0-691-12201-4 .

Web links

• "Lightfoot" is another word for nanosecond . (English). Accessed: May 24, 2016.
• Once she presented a piece of wire about a foot long, and explained that it represented a nanosecond . (English). Accessed: May 24, 2016.

Individual evidence

1. ↑ George Gamow: One Two Three ... Infinity - Facts and Speculations of Science . Dover Publications, New York 1961, ISBN 0-486-25664-2 , p. 77, selfdefinition.org ( memento of the original from August 5, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 14.3 MB; English); accessed May 24, 2016. 
2. ^ N. David Mermin: It's about Time: Understanding Einstein's Relativity . Princeton University Press, 2005, ISBN 978-0-691-12201-4 , p. 22.