6 ms·
Why is c the symbol for the speed of light? (1997)
- pizzafeelsright 3y agoFirst letter from the Latin for Speed.
- two_handfuls 3y agoThe article is a good read and adds some nuance to this answer.
- I_complete_me 3y agoI remember seeing a cartoon of Einstein at the blackboard on which the equation E=ma^2 (crossed out) then E=mb^2 (crossed out) and finally E=mc^2 with a beaming Einstein.
- montjoy 3y agoAnd here I was thinking it stood for Causality. Good to know.
- dotancohen 3y agoI always just assumed that it was Constant. I wonder what other inaccurate assumptions I have.
- elpocko 3y agoPerhaps your only other inaccurate assumption is to assume you have another inaccurate assumption.
- lucasRW 3y agoI did not know about that Latin term however I thought this came from the french since in the old time, many mathematicians and physicists used "celerite" instead of "vitesse" to talk about speed.
- magnusss 3y ago> The same Latin root is found in more familiar words such as acceleration and even celebrity, a word used when fame comes quickly. According to the OED, celebrity comes from the Latin “celebritās, [the] state of being busy or crowded, festival, games or other celebration characterized by crowded conditions, reputation, renown, fame, frequency or commonness.” https://www.oed.com/dictionary/celebrity_n?tab=etymology#9913378 https://www.oed.com/dictionary/celebrity_n?tab=etymology#991...
- schoen 3y agoI was going to make the same point! Wiktionary notes that celer and celeber could be related but are likely not. (I'm not sure whether there's more recent debate on this point.) https://en.wiktionary.org/wiki/celeber#Latin https://en.wiktionary.org/wiki/celeber#Latin
- guerrilla 3y agoWhich in turn may come from the same root. > From Proto-Italic kelizris, perhaps root cognate with clueo, from Proto-Indo-European ḱlew-; alternatively (if the rare meaning of "swift, in rapid succession" is to be taken as primary) connected with celer (with Greek κέλλω from a root *kel-). Jackson An Etymological Dictionary of the Latin Language (1828:77). Four citations given: https://en.wiktionary.org/wiki/celeber#References https://en.wiktionary.org/wiki/celeber#References
- bazoom42 3y agoYeah, a celebrity is someone who is celebrated. The “quick rise to fame” explanation seem like a folk-etymology.
- JacobAldridge 3y agoI always remember c as the constant speed of light [in a vacuum], but never pondered the actual origin beyond the perhaps rudimentary algebra “x, y, z are variables and a, b, c are constants”. I don’t think I thought c came from “constant”, because that’s a very English-centric view of science, but the annoying thing about reading a smart article like this is that it’s impossible to explore the depths of how your mind worked before acquiring the knowledge!
- guerrilla 3y agoI think it would have been 'k' if it stood for "constant" since most of them were German-speakers or collaborating with them.
- UncleSlacky 3y agok was already in use as Boltzmann's constant by that time, I think: https://en.wikipedia.org/wiki/Boltzmann_constant https://en.wikipedia.org/wiki/Boltzmann_constant
- Rygian 3y agoAs a tongue in cheek remark, it is English-centric to think that using c for constants is an English-centric view of science. French, Spanish, Italian, Portuguese, Romanian, all use the same word of Latin origin.
- tomatocracy 3y agoSomething related which I've not been able to find the root of - in some older British mathematics textbooks, F=ma is written instead p=mf (and this is definitely p meaning force and f acceleration and not an equivalent formula in terms of impulse or similar). I would love to know why these letters were used.
- schoen 3y agoThe p is probably Latin potentia or French puissance, but I'm not sure about the f!
- Telemakhos 3y agoThe p stands for impetus; i was already used for inertia, and m is in the same equation for mass, so p was the next best letter to use.
- jewillco 3y agohttps://mathoverflow.net/a/23258 https://mathoverflow.net/a/23258 claims it is from Latin “festinatio.”
- popol12 3y agoAre you sure you didn't read p=mg instead ? poids = masse * gravité weight = mass * gravity
- Levitz 3y agoIt is so, so refreshing to actually get an answer straight up instead of 6 paragraphs about the context, and how the author came to learn it, and what confusion might be, and how other constants have other names etc.
- Alifatisk 3y agoRight! Most articles I stumble upon nowadays is filled with everything besides the answer until I scroll to the bottom.
- codetrotter 3y agoThank the SEO practices for that :( It is often understood that in order to rank on Google you have to have a certain length to the content. So then what do people do when they want to write about something that has a simple answer? Why, pad it with heaps of unnecessary paragraphs of garbage text of course. All in the name of ranking. And what’s more is, the longer the text is the more space is available for inserting more ads to bombard the reader with as well. Which further serves to incentivise adding filler text that is not really useful to the reader.
- scott_w 3y agoYep, my understanding is that Google interprets you clicking then going back within a short period of time as “I didn’t find what I was looking for.”
- tjrgergw 3y agoYou name C things which are fast.
- chrisweekly 3y ago> Weber apparently meant c to stand for "constant" in his force law, but there is evidence that physicists such as Lorentz and Einstein were accustomed to a common convention that c could be used as a variable for velocity. This usage can be traced back to the classic Latin texts in which c stood for "celeritas" meaning "speed". The uncommon English word "celerity" is still used when referring to the speed of wave propagation in fluids. The same Latin root is found in more familiar words such as acceleration and even celebrity, a word used when fame comes quickly. Although the c symbol was adapted from Weber's constant, it was probably thought appropriate for it to represent the velocity of light later on because of this Latin interpretation. So history provides an ambiguous answer to the question "Why is c the symbol for the speed of light?", and it is reasonable to think of c as standing for either "constant" or "celeritas".
- kordlessagain 3y agoAll hail Weber’s Electrodynamics!
- wolverine876 3y ago> Although the c symbol was adapted from Weber's constant, it was probably thought appropriate for it to represent the velocity of light later on because of this Latin interpretation. Why do you say that? > So history provides an ambiguous answer to the question ... You provide an ambiguous answer, with no evidence (unless I misunderstand). That's not history.
- acheron 3y agoAlso related to “celery”, known as the fastest of all vegetables. (Joke of course, celery comes from Greek selinon)
- MayeulC 3y ago> Apart from in relativity, the most pervasive use of c to represent a speed today is in the wave equation This gives credence to what I was taught since high school, in French physics class: v=vitesse (speed), c=célérité (celerity). Speed is used when talking about physical object movement, celerity is used when talking about propagation of a phenomenon (wave speed). https://fr.wikipedia.org/wiki/C%C3%A9l%C3%A9rit%C3%A9 https://fr.wikipedia.org/wiki/C%C3%A9l%C3%A9rit%C3%A9 Though since c has come to specifically mean the speed of light is a vacuum as a notation, I see it used less often for other wave speeds when the constant is needed. Both speed and celerity are still used when writing and talking, with their respective meanings.
- valbaca 3y agoLight is how we “see”
- Groxx 3y agoSí, sí.
- thehappypm 3y ago2/3 of sunlight on earth hits the sea
- ttscar 3y agoThen C++ is a overflow because nothing can travel faster than the speed of light.
- unlitioldem 3y agoThe use of "c" as the symbol for the speed of light can be traced back to the pioneering work of the French physicist Augustin-Jean Fresnel in the early 19th century. In his research on light and optics, Fresnel used the letter "c" to represent the speed of light in his equations and formulas. The choice of "c" was likely influenced by the Latin word "celeritas" and its association with speed.