Why Is 'c' Used for the Speed of Light in E=mc²?

  • Thread starter Blackadder
  • Start date
In summary, the conversation discusses the origin and meaning of the symbol 'c' in the equation E=mc2. The letter was first used as a symbol for the speed of light in a 1856 paper and later became known as Weber's constant. The symbol was chosen because it represents 'celeritas' which means 'swiftness' in Latin and is related to the constant speed of light in a vacuum. The conversation also touches on the topic of the Big Bang and the origin of the universe, as well as the nature of light and electromagnetic radiation. Overall, the importance of the symbol 'c' is deemed insignificant and the conversation ends with the understanding that 'celeritas' means 'swiftness'.
  • #1
Blackadder
1
0
For my first thread allow me to answer a question posed by 'Artie' who requested the the following,

Unfortunately the thread was locked so I had to start a new thread just to answer this question.

(Quote Artie:)In the equation E=mc2

E is energy

m is mass

What is c? I know that c is the speed of light, but why use the letter c? What does c stand for? (Unquote)

The first use of the letter c as a symbol for the speed of light was in a 1856 paper by Wilhelm Eduard Weber and Rudolf Kohlrausch. Weber used the notation to stand for constant, and it later become known as Weber's constant.

Lower case 'c' stood for celeritas as was stated previously but the Latin celeritas actually means 'swift'. Plank, Lorentz, and ultimately Einstein used the letter 'c' and in Eistein's case, his theory of relativity demanded the speed of light in a vacuum be 'constant' thereby finessing a double entendre to the symbol.

The first quantitative estimate of the speed of light was made in 1676 by Ole Christensen Romer whose estimate of approximately 136,000 miles per second based on astronomical observations of the moons of Jupiter was in the ballpark but about 26% too low. Although for a first shot it was magnificent.

It took me some time to find this Forum and I have some interesting questions on the Big Bang and the origin of the universe and my own hypothesis on the 'Intelligent design imbroglio'.

Looking forward to exchanging ideas and some good debates.

The Blackadder
 
Last edited:
Physics news on Phys.org
  • #2
What's your question?

It really is not important what symbol is used to represent a physical quantity. If your question has to do with the nature of light/ electromagnetic radiation then I recommend that you read the FAQs on this site.

If you want to know why the symbol c is used then read the thread you are referring to. There is really not much else to say.
 
  • #3
... the Latin celeritas actually means 'swift'.
It means 'swiftness'. 'Celer' means 'fast' or 'swift'.

M
 
  • #4
Mentz114 said:
It means 'swiftness'. 'Celer' means 'fast' or 'swift'.
Yes. Even in italian, "celere" means "fast, rapid".
 

FAQ: Why Is 'c' Used for the Speed of Light in E=mc²?

What is the meaning of "E=mc²"?

"E=mc²" is a famous equation developed by Albert Einstein that explains the relationship between energy (E), mass (m), and the speed of light (c). It states that energy and mass are interchangeable and can be converted into one another.

Why is "E=mc²" important?

"E=mc²" is important because it revolutionized our understanding of the fundamental laws of the universe. It led to the development of nuclear power and weapons, and it also helped scientists better understand the concept of relativity.

Can you explain the "redux" part of "E=mc² redux"?

"Redux" refers to a revised or updated version of something. In this case, "E=mc² redux" is a modern interpretation of Einstein's original equation, taking into account new scientific discoveries and advancements.

How does "E=mc²" relate to the theory of relativity?

"E=mc²" is a key component of Einstein's theory of relativity. It explains how energy, mass, and the speed of light are all interconnected and affected by the laws of relativity. This equation helps us understand the concept of mass-energy equivalence, which is a fundamental principle of the theory of relativity.

What are some real-world applications of "E=mc²"?

"E=mc²" has several real-world applications, including the development of nuclear power and nuclear weapons. It also helps scientists understand the formation of stars and the energy released during nuclear reactions. Additionally, it has applications in fields such as astrophysics, quantum mechanics, and particle physics.

Similar threads

Back
Top