Fabian Lapp

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Why does E=mc²?

I think we can all agree that 1=1 but how can you say that E=mc². No one would say the E is the same letter as m.
One example I'd like to make is that NaCl=Na+ + Cl-
But in chemistry you do not use the equals sign you use arrows that indicate a process of conversion which is reversible.
Just as the conversion from energy to mass.

  • Jun 13 2013: I can't tell if you are being sincere with your question. I personally think you are confusing the concepts of abbreviations and variables.

    In your examples, Na and Cl are abbreviations for the names of elements. They are a type of shorthand that chemists created to help describe the work that they do. They mean very specific items in the chemical world. You pointed out yourself they also used a special kind of shorthand to show that a conversion takes place - the arrow.

    But in this case "E" is a variable in the model of a scientific idea and if you were to go read the scientific papers that Einstein wrote to explain the theory of relativity you would see that that "E" has a very specific meaning in this case. In fact, look at all the different meaning "E" or "e" can have in different subject areas.

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    May 20 2013: Well I'm trying to say that E cannot equal mass times speed of light squared because only E can equal E.
    Or in the words of Robert Recorde,"...because no two things can be more equal."[taken from wikipedia]
    That's why I want to see arrows used just as is commonplace in chemistry because NaCl cannot equal Na+ plus Cl-.
    But Na+ and Cl- can bond toegther to form NaCl and ONLY through this process of bonding which takes time[among other things] can be equal to NaCl.
    Hope that makes sense.
    • Jun 13 2013: Are you arguing that

      16 + 16 cannot equal 32
      8 * 4 cannot equal 32
      64 / 2 cannot equal 32
      the square root of 1024 cannot equal 32
      42 - 10 cannot equal 32
      because only 64 = 64.

      Because that is what your question is asking.
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    May 20 2013: In the equation D (distance travelled)= V (speed/time) X T (time travelled), it is not inferred that distance is interchangeable with speed or time. Are you saying in E=mc^2 energy, measured in Ergs, is interchangeable with mass, measured in grams, and the square of the speed of light in a vacuum, measured in Km/sec.? I agree that in the equation 16= 32/2 the quantity 32 when halved is interchangeable with the quantity 16, but that does not mean 16 is interchangeable with 32, or with 2. Have i missed your point?
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    May 19 2013: E = mc^2 does not imply that mass may be converted to energy but it allows for matter to be converted to energy. Mass and matter are not exactly the same. E = mc^2 essentially states that all energy is mass and vice verse.
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    May 19 2013: I am trying to say that only E=E. Whereas if energy equals mass a process of conversion were to need to take place which transforms energy to mass but in order to do so takes TIME.
  • May 19 2013: I just remember seeing it fall out of some equations in my undergraduate days in 1970 or1971. Einstein apparently wanted to use " L" initially.
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      May 19 2013: Energy itself is one, and mass is another one. E = mc² says is that matter and energy are interchangeable.
      Energy can transform into matter and matter can transform into energy. They are just different pieces of the same puzzle, and both of them can be derivative of something else, mass could be in a different "currency" such as protons and neutrons, then be converted to mass and be interchanged with Energy.
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    May 18 2013: I am not sure about what you are trying to say but I like your way to think! I think we have to remember the fact that they are different units and they must be converted (or at least equivalent), just like U$:1,00 = EUR:0.77 or just as simple as KE = 1/2 mv^2.