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Encyclopedia > Celeritas

Celeritas is a Latin word, translated as "swiftness" or "speed". It is often given as the origin of the symbol c, the universal notation for the speed of light in a vacuum, as popularised in Albert Einstein's famous equation E=mc². Also, according to Georges Dumézil, Celeres were also the bodyguards of the first Luperci. Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness. In metric units, c is exactly 299,792,458 metres per second (1,079,252,848. ... Look up Vacuum in Wiktionary, the free dictionary. ... Einstein redirects here. ... A display of the famous equation on Taipei 101 during the event of the World Year of Physics 2005. ... Georges DumÃ©zil (March 4, 1898 - October 11, 1986) was a French comparative philologist best known for his analysis of sovereignty and power in Indo-European religion and society. ...

## Origins of the "c" notation GA_googleFillSlot("encyclopedia_square");

In the nineteenth century, an upper-case V was commonly used to describe the speed of light. This was the notation used by Einstein in his 1905 papers, thus his most famous equation was originally written as m=L/V² (E having being used elsewhere for a different energy) [1]. The first use of the letter c being used to describe the speed of light can be traced to a paper in 1856 by Wilhelm Eduard Weber and Rudolf Kohlrausch[2]. Weber used the notation to stand for constant and it later become known as Weber's constant. At the turn of the 20th century, the letter c was popularised by influential physicists such as Max Planck and Hendrik Lorentz and in 1907 Einstein switched his notation from V to c in his papers. Wilhelm Eduard Weber Wilhelm Eduard Weber (October 24, 1804 - June 23, 1891) was a noted physicist. ... In mathematics and the mathematical sciences, a constant is a fixed, but possibly unspecified, value. ... The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness. In metric units, c is exactly 299,792,458 metres per second (1,079,252,848. ... Max Karl Ernst Ludwig Planck (April 23, 1858 â€“ October 4, 1947) was a German physicist. ... Painting of Hendrik Lorentz by Arnhemensis Hendrik Antoon Lorentz (July 18, 1853, Arnhem â€“ February 4, 1928, Haarlem) was a Dutch physicist and the winner of the 1902 Nobel Prize in Physics for his work on electromagnetic radiation. ...

## How "c" came to stand for celeritas

It is thought that that Weber originally intended the letter c to stand for "constant" as opposed to celeritas. The first reference to c standing for celeritas can be found in a 1959 essay by science fiction author Isaac Asimov, in his essay, he stated "C is for celeritas"[3] though he cited no evidence to support this. In mathematics and the mathematical sciences, a constant is a fixed, but possibly unspecified, value. ... Isaac Asimov, Ph. ...

It is now standard to see "c is for celeritas" stated as fact, and a common quiz answer; though some may continue to question the origion. David Bodanis in his popular science book, E=mc²: A Biography of the World's Most Famous Equation, states that "[the speed of light] has this unsuspected letter for its name probably out of homage for the period before the mid 1600s when science was centred around Italy, and Latin was the language of choice, Celeritas is the Latin word for swiftness."[4]

## References

1.   A. Einstein, Annalen der Physik, Band 18, 1905
2.   R. Kohlrausch and W.E. Weber, "Ueber die Elektrizitätsmenge, welche bei galvanischen Strömen durch den Querschnitt der Kette fliesst", Annalen der Physik, 99, pg. 10 (1856)
3.   Isaac Asimov "C for Celeritas" in "The Magazine of Fantasy and Science Fiction", Nov-59 (1959), reprinted in "Of Time, Space, and Other Things", Discus (1975), and "Asimov On Physics", Doubleday (1976)
4.   David Bodanis, "E=mc² A Biography of the World's Most Famous Equation", pg. 37, Macmillan (2000)

Results from FactBites:

 Intellectual Property Owners Association | Celeritas Technologies, Ltd. v. Rockwell International Corp. 97-1512, -1542 (4187 words) Celeritas and Rockwell acknowledge that the extent of damages in the event of the breach of any provision of this Agreement would be difficult or impossible to ascertain, and that there will be available no adequate remedy at law in the event of any such breach. Celeritas argues that in order for a trade secret to enter the public domain in California, it must actually have been ascertained by proper means, and not merely have been ascertainable. Celeritas responds that Rockwell has a heavy burden in sustaining that position because the Telebit article was disclosed to the PTO during prosecution of the '590 patent and the patent obviously was granted despite the existence of that reference.
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